World War II

World War II (abbreviated to WWII), or the Second World War, was a worldwide conflict fought between the Allied Powers from 1939 until 1945. Armed forces from over seventy nations engaged in aerial, naval and ground-based combat. Spanning much of the globe, World War II resulted in the deaths of over 100 million people, making it the deadliest conflict in human history. The war ended with an Allied victory.
==Overview==
===War in Europe===
On September I, 1939, Germany, led by Adolf Hitler and the Nazi Party, invaded Poland according to a secret agreement with the Soviet Union. 
On September 3 at 11:15 GMT, the United Kingdom, Australia, New Zealand, followed six hours later by France, responded by declaring war on Germany, initiating a widespread naval war. South Africa (September 6) and Canada (September 10) followed suit. 
The Soviet Union joined the invasion of Poland on September 17.
Germany rapidly overran Poland, then Norway, the Netherlands, Belgium and France in 1940, and Yugoslavia and Greece in 1941. Italian and later German troops attacked British forces in North Africa. By summer of 1941, Germany had conquered France and most of Western Europe, but it failed to subdue the United Kingdom thanks to the resistance of the Royal Air Force and Royal Navy.
Adolf Hitler then turned on the Soviet Union, launching a surprise attack (codenamed Operation Barbarossa) on June 22, 1941. Despite enormous gains, the invasion stalled on the outskirts of Moscow in late 1941, as the winter weather made further advances difficult. The Germans initiated another major offensive the following summer, but the attack bogged down in vicious urban fighting in Stalingrad. The Soviets later launched a massive encircling counterattack to force the surrender of the German Sixth Army at the Battle of Stalingrad (1942–43), decisively defeated the Axis at the Battle of Kursk, and broke the Siege of Leningrad. The Red Army then pursued the retreating Wehrmacht to Berlin, and won the street-by-street Battle of Berlin, as Hitler committed suicide in his underground bunker on April 30, 1945.
Meanwhile, the Western Allies successfully defended North Africa (1940–43), invaded Italy (1943), and then liberated France (1944), following amphibious landings in Normandy. After repulsing a German counterattack at the Battle of the Bulge that December, the Western Allies crossed the Rhine River to link up with their Soviet counterparts at the Elbe River in central Germany.
During the war in Europe, some 6 million Jews, along with another 5 to 6 million people — Roma (Gypsies), Slavs, Communists, homosexuals, the disabled and several other groups — were murdered by Germany in a state-sponsored genocide that came to be known as the Holocaust.
===War in Asia and the Pacific===
The Empire of Japan, already in Manchuria since 1931, invaded China on July 7, 1937. Australia and then the United States, in 1940, responded with embargoes on iron exports to Japan. On September 27, 1940 Japan signed the Tripartite Pact with Germany and Italy. After fruitless negotiations with the United States concerning withdrawal from China, excluding Manchukuo, Japan attacked Vichy French-controlled Indochina on July 24, 1941. This caused the United States, United Kingdom and Netherlands to block Japan's access to oil, such as that in the Dutch East Indies and British colonies in Borneo.
Japan launched nearly simultaneous surprise attacks against the major U. S. Navy base at Pearl Harbor, on Thailand and on the British territories of Malaya and Hong Kong. Though it was significant to the US Navy, most Americans had never heard of Pearl Harbor. The attacks occurred on December 7, 1941 in western international time zones and on December 8 in the east. Later on December 8, Japan attacked The Philippines, which was politically controlled by the United States at the time and quickly fell to Japanese forces. On December 11, Germany and Italy also declared war on the United States. Japanese forces commenced assaults on British and Dutch territory in Borneo on December 15. From their major prewar base at Truk in the South Pacific, Japanese forces began to attack and occupy neighboring Allied territories.
Japan's campaign in China lasted from 1937 to the end of the war, during which the Republic of China faced 80% of Japanese troops and relieved the Soviet Union under Stalin from fighting a two-front war. In the war against Japan, China lost more than 3 million soldiers and more than 17 million civilians. Many others were tortured, forced into slavery or raped, which resulted in charges of Japanese war crimes.
Japan won victory after victory in South East Asia and the Pacific, including the capture of 130,000 Allied prisoners in Malaya and at the fall of Singapore on February 15, 1942. Much of Burma, the Netherlands East Indies, the Australian Territory of New Guinea, and the British Solomon Islands also fell to Japanese forces.
The Japanese advance was checked at the Battle of the Coral Sea and their invasion fleet turned away from New Guinea after Allied naval forces clashed in the first battle in which the opposing fleets never made visual contact. A month later a Japanese invasion fleet was decisively defeated at the Battle of Midway in which they lost four fleet aircraft carriers attempting to engage U.S. Navy forces (the U.S. Navy lost one carrier). On land they were defeated at the Battle of Milne Bay, were pushed out of Papua New Guinea by predominantly Australian forces through the Kokoda Trail and finally withdrew from Battle of Guadalcanal as the Allies took the initiative in the Solomon Islands and began an "Island Hopping" campaign to push back Japanese holdings in the Pacific. U.S. and Australian forces then isolated Japan's major base at Rabaul before advancing from one island to another in the Central Pacific invading some and isolating others. The Japanese were defeated in a series of great naval battles, at the Battle of the Philippine Sea and the Battle of Leyte Gulf in 1944 in which the Allies further advanced towards the Japanese homeland by invading the Marianas and then the Philippines, setting up bases from which Japan could be bombed by strategic bombers like the B-29. 1945 saw invasions of key islands such as Iwo Jima and Okinawa. In the meantime, Allied submarines gradually cut off the supply of oil and other raw materials to Japan.
In the last year of the war US air forces conducted a strategic firebombing campaign against the Japanese homeland. On August 6, 1945, the U.S. dropped an atomic bomb on the Japanese city of Hiroshima, and on August 9 another was dropped on Nagasaki. On the same day the Soviets joined the Pacific campaign in Manchuria, quickly defeating the Japanese Kwantung Army there. Japan surrendered on August 14, 1945.
===Aftermath===
About 62 million people, or 2.5% of the world population, died in the war, though estimates vary widely (see World War II casualties). Large swaths of Europe and Asia were devastated and took years to recover. The war had political, sociological and economic repercussions that persist to this day.
==Causes==
 
The immediate causes of World War II are generally held to be the German invasion of Poland, as well as the Japanese attacks on China, the United States, and the British and Dutch colonies. All of the attacks resulted from the leadership of authoritarian ruling elites in Germany and Japan. World War II began after these acts of aggression were met with an official declaration of war or armed resistance.
===Cause of war in Europe===
Germany and France had been struggling for dominance in Continental Europe for fifty years, and fought two previous wars, the Franco-Prussian War, and World War I. Meanwhile the power of the Soviet Union threatened to eclipse them both as industrialization spread to this massive country. World War I had been a preemptive war by Germany against the precursor to the Soviet Union, the Russian Empire, Fromkin, David. 2005. Europe's Last Summer: Who Started the Great War in 1914? (Paperback) Vintage; Reprint edition (March 8, 2005) ISBN 978-0375725753 but it ended in catastrophe for the Germans, with millions dead, the loss of some peripheral territory, and economic hardships. 
In the six years preceding World War II, Adolf Hitler, leading the Nazi Party, took power in Germany and eliminated its democratic government, the Weimar Republic. As stated in Mein Kampf, an autobiographical book outlining his plans for the future, Hitler's goal was to invade and conquer lands around Germany, and to make them German. He railed against Communists and ethnic minorities, such as Jews. After taking power, he prepared Germany for another war with large political rallies and speeches. 
During the late 1930s Hitler abrogated the Treaty of Versailles, which had brought peace after WWI. He remilitarized the Rhineland, and increased the size of the German army, navy, and air force. 
The British and French governments followed a policy of appeasement in order to avoid a new European war, out of concern for perceived war-weariness of their populations due to the huge death tolls of the first World War. This policy culminated in the Munich Agreement in 1938, in which the seemingly inevitable outbreak of the war was averted when the United Kingdom and France agreed to Germany's annexation and immediate occupation of the German-speaking regions of Czechoslovakia. In exchange for this, Hitler gave his word that Germany would make no further territorial claims in Europe.Chamberlain's radio broadcast, 27 September 1938Churchill, Winston S. The Second World War. (6 volumes). (1948-1953). ISBN 978-0395416853 Chamberlain declared that the agreement represented "peace for our time." In March 1939, Germany invaded the rest of Czechoslovakia, effectively killing any notions of appeasement.
The failure of the Munich Agreement showed that negotiations with Hitler could not be trusted, as his aspirations for dominance in Europe went beyond anything that the United Kingdom and France would tolerate. Poland and France pledged on May 19, 1939 to provide each other with military assistance in the event either was attacked. The British had already offered support to Poland in March. 
On August 23, 1939, Germany and the Soviet Union signed the Molotov-Ribbentrop Pact. The Pact included a secret protocol that would divide Central Europe into German and Soviet areas of interest, including a provision to partition Poland. Each country agreed to allow the other a free hand in its area of influence, including military occupation. The deal provided for sales of oil and food from the Soviets to Germany, thus reducing the danger of a British blockade such as the one that had nearly starved Germany in World War I. Hitler was then ready to go to war with Poland and, if necessary, with the United Kingdom and France. He claimed there were German grievances relating to the issues of the Free City of Danzig and the Polish Corridor, but he planned to conquer all Polish territory to incorporate it into the German Reich. The signing of a new alliance between the United Kingdom and Poland on August 25 did not significantly alter his plans.
On September 1, 1939, Germany invaded Poland, causing France and the United Kingdom to declare war. The United Kingdom brought with it the huge British Empire, and most members of the British Commonwealth joined the war soon after.
===Cause of war in Asia===
Main articles : Showa Era, Militarism-Socialism in Showa Japan, Japanese nationalism
Following the policies adopted after the Treaty of Versailles by occidental powers toward the recognition of Japan as a colonial power, many politicians and militarist leaders such as Fumimaro Konoe and Sadao Araki brought back the concept of hakko ichiu and promoted the right of Japan to conquer Asia and unify it under the rule of emperor Showa, the offspring of Amaterasu Omikami. 
Japan invaded Manchuria in 1931 and China in 1937 to bolster its meager stock of natural resources, to relieve Japan from population pressures and to extend its colonial realm to a wider area. This invasion became a "holy war" (seisen) and was followed by a harsh occupation with many atrocities against civillians ( Nanking massacre, sanko sakusen). The United States and the United Kingdom reacted by making loans to China, providing covert military assistance, pilots and fighter aircraft to the Chinese Kuomintang and instituting after 1940 broad natural resource embargoes against Japan. The embargoes could have ultimately forced Japan to give up its newly conquered possessions in China or find new sources of oil and other resources. 
Japan was faced with the choice of withdrawing from China, negotiating some compromise, developing new sources of supply, buying what they needed somewhere else, or going to war to conquer the territories that contained oil, bauxite and other resources in the Dutch East Indies, Malay and the Philippines. Japan's leaders believed that the French, Dutch, Soviet and British governments were preoccupied with the war in Europe, and that the United States could not be war-ready for years and would compromise before waging full-scale war. Japan thus proceeded with its plans for the war in the Pacific, and invaded and conquered nations and colonial possessions throughout Asia and the Pacific.http://www.anesi.com/ussbs01.htm 
For propaganda purposes, Japan's leaders stated that the goal of its military campaigns was to create the Greater East Asia Co-Prosperity Sphere. This, they claimed, would be a co-operative league of Asian nations, freed by Japan from European imperialist domination, and liberated to achieve autonomy and self-determination. In practice, occupied countries and peoples were completely subordinate to Japanese authority. 
The direct cause of the United States' entry into the war with Japan was the attack on Pearl Harbor on December 7, 1941. Germany declared war on the United States on December 11, 1941.
==Chronology==
===War breaks out in Asia (July 1937 – September 1939)===
The Second Sino-Japanese War began in 1937, when Japan attacked deep into China from its foothold in Manchuria (Northeast China). On July 7, 1937, Japan, after occupying Manchuria since 1931, launched another attack against China near Beijing. The Japanese made initial advances but were stalled in the Battle of Shanghai. The city eventually fell to the Japanese in December 1937, and the capital city Nanjing also fell. As a result, the Chinese Nationalist government moved its seat to Chongqing for the remainder of the war. The Japanese forces committed brutal atrocities against civilians and prisoners of war in the Rape of Nanking, slaughtering as many as 300,000 civilians within a month. Neither Japan or China officially declared war, for a similar reason—fearing declaration of war would alienate Europe and the United States.
In Spring 1939, Soviet and Japanese forces clashed in Mongolia. The growing Japanese presence in the Far East was seen as a major strategic threat by the Soviet Union, and Soviet fear of having to fight a two front war was a primary reason for the Molotov-Ribbentrop Pact with the Nazis (other historians mention Munich Agreement as a supposition to this pact). The Japanese invasion of Mongolia was repulsed by Soviet units under General Georgiy Zhukov. Following this battle, the Soviet Union and Japan were at peace until 1945. Japan looked south to expand its empire, leading to conflict with the United States over the Philippines and control of shipping lanes to the Dutch East Indies. The Soviet Union focused on the west, leaving only minimal troops to guard the frontier with Japan.
===War breaks out in Europe (September 1939 – May 1940)===
On September 1, 1939, Germany invaded Poland, using the false pretext of a faked "Polish attack" on a German border post. The United Kingdom and France gave Germany two days to withdraw from Poland. Once the deadline passed on September 3, the United Kingdom, Australia, and New Zealand declared war on Germany, followed quickly by France, South Africa, Canada and Nepal. Immediately, Great Britain began seizing German ships and implementing a blockade.
Despite the French and British treaty obligations and promises to the Polish government, both France and Great Britain were unwilling politically to launch a land invasion of Germany. The French mobilized slowly and then mounted only a short a token offensive in the Saar; neither did the British send land forces in time to support the Poles (see Western betrayal). Meanwhile, on September 8, the Germans reached Warsaw, having slashed through the Polish defenses.
On September 17, the Soviet Union, pursuant to its secret agreement with Germany, invaded Poland from the east, throwing Polish defenses into chaos by opening the second front. A day later, both the Polish president and commander-in-chief fled to Romania. On October 1, hostile forces, after a one-month siege of Warsaw, entered the city. The last Polish units surrendered on October 6. Poland, however, never officially surrendered to the Germans. Some Polish troops evacuated to neighboring countries. In the aftermath of the September Campaign, occupied Poland managed to create a powerful resistance movement and contributed significant military forces to the Allies for the duration of World War II.
After Poland fell, Germany paused to regroup during the winter of 1939–1940 until April 1940, while the British and French stayed on the defensive. The period was referred to by journalists as “the Phony War” or the “Sitzkrieg” because so little ground combat took place. During this period Soviet Union attacked Finland on November 30, 1939, which started the Winter War. Despite outnumbering Finnish troops by 4 to 1, the Red Army found the attack embarrassingly difficult, and the Finnish defence prevented an all-out invasion. Finally, however, the Soviets prevailed and the peace treaty saw Finland cede strategically important border areas near Leningrad.
Germany invaded Denmark and Norway on April 9, 1940, in Operation Weserübung. Denmark did not resist, but Norway fought back. The Norwegian defense was undermined by the collaboration of Vidkun Quisling, whose name is now synonymous with "traitor". The United Kingdom, whose own invasion was ready to launch, landed in the north. By late June, the Allies were defeated and withdrew, Germany controlled most of Norway, and the Norwegian Army had surrendered, while the Norwegian Royal Family escaped to London. Germany used Norway as a base for air and naval attacks on Arctic convoys headed to the Soviet Union. Norwegian partisans would continue to fight against the German occupation throughout the war.
===The Western Front (May 1940 – September 1940)===
The Germans ended the Phony War on May 10, 1940 when they invaded Luxembourg, Belgium, the Netherlands, and France. The Netherlands was quickly overwhelmed and the Dutch city of Rotterdam was destroyed in a bombing raid. The British Expeditionary Force (BEF) and the French Army advanced into northern Belgium and planned to fight a mobile war in the north, while maintaining a static continuous front along the Maginot Line further south. The Allied plans were immediately smashed by the most classic example in history of Blitzkrieg. 
In the first phase of the invasion, Fall Gelb, the Wehrmacht's Panzergruppe von Kleist, raced through the Ardennes, a heavily forested region which the Allies had thought impenetrable for a modern, mechanized army. The Germans broke the French line at Sedan, held by reservists rather than first-line troops, then drove west across northern France to the English Channel, splitting the Allies in two.
The BEF and French forces, encircled in the north, were evacuated from Dunkirk in Operation Dynamo. The operation was one of the biggest military evacuations in history, as 338,000 British and French troops were transported across the English Channel on warships and civilian boats.
On June 10, Italy joined the war, attacking France in the south. German forces then continued the conquest of France with Fall Rot (Case Red). France signed an armistice with Germany on June 22 1940, leading to the direct German occupation of Paris and two-thirds of France, and the establishment of a German puppet state headquartered in southeastern France known as Vichy France.
Germany had begun preparations in the summer of 1940 to invade the United Kingdom in Operation Sea Lion. Most of the British Army's heavy weapons and supplies had been lost at Dunkirk. The Germans had no hope of overpowering the Royal Navy, but they did think they had a chance of success, if they could gain air superiority. To do that, they first had to deal with the Royal Air Force (RAF). The ensuing contest in the late Summer of 1940 between the two air forces became known as the Battle of Britain. The Luftwaffe initially targeted RAF Fighter Command aerodromes and radar stations. Hitler, angered by retaliatory bombing raids on Berlin, switched his attentions towards the bombing of London, in an operation known as The Blitz. The Luftwaffe was eventually beaten back by Hurricanes and Spitfires, while the Royal Navy remained in control of the English Channel. Thus, the invasion plans were postponed indefinitely.
After France had fallen in 1940, the United Kingdom was out of money. Franklin Roosevelt persuaded the U.S. Congress to pass the Lend-Lease act on March 11 1941, which provided the United Kingdom and 37 other countries with US$50 billion dollars in military equipment and other supplies, US$31.4 billion of it going to the United Kingdom and the Commonwealth. Canada operated a similar program that sent $4.7 billion in supplies to the United Kingdom.
===The Mediterranean (April 1940 – May 1943)===
Control of Southern Europe, the Mediterranean Sea and North Africa was important because the British Empire depended on shipping through the Suez Canal. If the canal fell into Axis hands or if the Royal Navy lost control of the Mediterranean, then transport between the United Kingdom, India, and Australia would have to go around the Cape of Good Hope, an increase of several thousand miles. 
Following the French surrender, the British attacked the French Navy anchored in North Africa in July 1940, out of fear that it might fall into German hands. This contributed to a souring of British-French relations for the next few years. With the French fleet destroyed, the Royal Navy battled the Italian fleet for supremacy in the Mediterranean from their strong bases at Gibraltar, Malta, and Alexandria, Egypt. 
Italy invaded Greece on October 28, 1940, from Italian occupied Albania, but was quickly repulsed. By mid-December, the Greek army advanced into southern Albania, tying down 530,000 Italian troops. Meanwhile, in fulfillment of Britain's guarantee to Greece the Royal Navy struck the Italian fleet on November 11, 1940. Torpedo bombers from British aircraft carriers attacked the Italian fleet in the southern port of Taranto. One battleship was sunk and several other ships were put temporarily out of action. The success of aerial torpedoes at Taranto was noted with interest by Japan's naval chief, Yamamoto, who was considering ways of neutralizing the U.S. Pacific Fleet. Mainland Greece eventually fell to a German invasion from the East, through Bulgaria.
Italian troops crossed into Egypt from Libya to attack British bases in September 1940, thus beginning the North African Campaign. The aim was to capture the Suez Canal. British, Indian and Australian forces counterattacked in Operation Compass, which stopped in 1941 after numerous Australian and New Zealand (ANZAC) forces were transferred to Greece to defend it from German attack. German forces (known later as the Afrika Korps) under General Erwin Rommel landed in Libya in February 1941 to renew the assault on Egypt.
Germany also invaded Crete, significant for the large-scale use of German paratroopers. Crete was defended by about 11,000 Greek and 28,000 ANZAC troops, who had just escaped Greece without their artillery or vehicles. The Germans attacked the three main airfields of the island of Maleme, Rethimnon, and Heraklion. After one day of fighting, none of the objectives were reached and the Germans had suffered appalling casualties. German plans were in disarray and the German commander, General Kurt Student, was contemplating suicide. During the next day, through miscommunication and failure of Allied commanders to comprehend the situation, Maleme airfield in western Crete fell to the Germans. The loss of Maleme enabled the Germans to fly in heavy reinforcements and overwhelm the Allied forces on the island. In light of the heavy casualties suffered by the parachutists, however, Hitler forbade further airborne operations.
In North Africa, Rommel's forces advanced rapidly eastward, laying siege to the vital seaport of Tobruk. Two Allied attempts to relieve Tobruk were defeated, but a larger offensive at the end of the year (Operation Crusader) repelled Rommel's forces after heavy fighting.
The war between the Allied and Italian navies swung decisively in favor of the Allies on March 28, 1941, when Admiral Cunningham's ships encountered the main Italian fleet south of Cape Matapan, at the southern extremity of the Greek mainland. At the cost of a couple of aircraft shot down, the Allies sank five Italian cruisers and three destroyers, and damaged the modern battleship Vittorio Veneto. The Italian Navy was emasculated as a fighting force, and the Allied task of moving troops across the Mediterranean to Greece was eased.
On April 6, 1941, German, Italian, Hungarian, and Bulgarian forces invaded Yugoslavia, ending with the surrender of the Yugoslav army on April 17, and the creation of client states in Croatia and Serbia. Also on April 6, Germany invaded Greece from Bulgaria. The Greek army defending the Metaxas Line was outnumbered and outmaneuvered by the rapid German advance through Yugoslavia and collapsed. Athens fell on April 27, yet the United Kingdom managed to evacuate over 50,000 troops.
Resistance broke out in Yugoslavia in mid-1941, centered around two movements: the Communist-led Partisans, commanded by Tito, and the royalist Chetniks led by Draža Mihailović. The two paramilitaries briefly cooperated in 1941 but soon fell out, with the Chetniks assuming a more ambivalent role, frequently siding with the occupying forces against the communists.
In April-May 1941, there was a short war in Iraq that resulted in a renewal of British occupation. In June, Allied forces invaded Syria and Lebanon, and captured Damascus on June 17. Later, in August, UK and Red Army troops occupied neutral Iran, securing its oil and a southern supply line to the Soviet Union.
At the beginning of 1942, the Allied forces in North Africa were weakened by detachments to the Far East. Rommel once again recaptured Benghazi. He then defeated the Allies at the Battle of Gazala, and captured Tobruk along with several thousand prisoners and large quantities of supplies, before drivng deeper into Egypt.
The First Battle of El Alamein took place in July 1942. Allied forces had retreated to the last defensible point before Alexandria and the Suez Canal. The Afrika Korps, however, had outrun its supplies, and the defenders stopped its thrusts. The Second Battle of El Alamein occurred between October 23 and November 3. Lieutenant-General Bernard Montgomery was in command of Allied forces known as the Eighth Army. The Allies took the offensive and, despite initially stiff German resistance, were ultimately triumphant. After the German defeat at El Alamein, the Axis forces made a successful strategic withdrawal to Tunisia.
Operation Torch was launched by the U.S., British and Free French forces on November 8, 1942, to gain control of North Africa through simultaneous landings at Casablanca, Oran and Algiers, followed a few days later by a landing at Bône, the gateway to Tunisia. The local forces of Vichy France put up minimal resistance before submitting to the authority of Free French General Henri Giraud. In retaliation, Hitler invaded and occupied Vichy France. The German and Italian forces in Tunisia were caught in the pincers of Allied advances from Algeria in the west and Libya in the east. Rommel's tactical victory against inexperienced American forces at the Battle of the Kasserine Pass only postponed the eventual surrender of the Axis forces in North Africa in May 1943.
In 1943 the Axis almost succeeded in wiping out Yugoslav Partisan resistance. From January to April, the guerillas were forced to flee eastwards in winter conditions over the rough terrain of Bosnia, suffering heavy losses, eventually crossing the Neretva river and securing their command and the hospital. They continued eastwards, incapacitating the Chetnik forces in the area, and fell into a near-fatal German encirclement in the Sutjeska valley in late May.
===Sub-Saharan Africa (July 1940 – September 1943)===
Italy had gained control of Eritrea and Italian Somaliland during the colonial Scramble for Africa, and had taken Ethiopia prior to the outbreak of World War II during the Second Italo-Abyssinian War (1935–1936). These three colonies were reorganized into the dominion of Italian East Africa.
During early 1940, Italian colonial forces consisted of 80,000 Italian troops and 200,000 native troops, while British forces in all of British Somaliland, Kenya and Sudan only amounted to 17,000.. The Italians first amassed in preparation of taking French Somaliland (now known as Djibouti). This attack was called off with the collapse of the French army and the installation of the neutral government of Vichy France. In July, Sudanese border towns of Kassala and Gallabat were occupied by an Italian force of 50,000, and in August 1940, the Italian colonial army attacked and took British Somaliland using a force of 25,000. This gave Italy control of nearly all of the Horn of Africa.
In September 1940, Allied forces failed during the Battle of Dakar to take the capital of Senegal from the Vichy French troops defending it; French West Africa remained Vichy until the Operation Torch landings in North Africa in November 1942. Yet in November, the Allies succeeded in the Battle of Gabon, solidifying control over French Equatorial Africa for the Free French Forces.
Also in November 1940, the British began a counteroffensive from Sudan against Italian-held Gallabat with only 7,000 troops, which was unable to make much headway. However in January 1941, the Italian army withdrew its forces in the Sudanese border towns to more defensible terrain to the east of Kassala. With additional reinforcements from the British Indian Army and South Africa, the campaign began to make progress. British Somaliland was retaken in March, and Addis Ababa, capital of Ethiopia, was captured on April 6. Emperor Haile Selassie I returned to the city on May 5. However, a force of Italians continued to fight a guerrilla war in Ethiopia until the Italian surrender of September 1943.
Madagascar, as a French colony, was considered enemy territory by the British after the creation of the collaborationist Vichy regime. It was also the suggested land to which European Jews should be deported, in an anti-Semitic proposition known as the "Madagascar Plan." While the British still controlled Egypt and the Suez Canal, such German plans were impossible, and eventually they were shelved in favor of a genocidal campaign, which was termed the "Final Solution." With the advent of the Japanese entrance to the war in December 1941, and the surrender of Singapore in February 1942, the Allies became increasingly worried Madagascar would fall to the Axis. Therefore, they conducted an invasion known as Operation Ironclad in May 1942. Fighting lasted there against the Vichy French defenders until November, who were backed by several Japanese submarines. In December, French Somaliland was also taken by the British.
After the landings of Operation Torch, the remainder of Vichy territories in Africa came under the control of the Allies. With the southern continent generally secure, apart from the Italian insurgency in Ethiopia, the Allies turned their attention to other theatres.
===The Eastern Front (April 1941 – January 1942)===
 
The battle of Greece and the invasion of Yugoslavia delayed the German invasion of the Soviet Union by a critical six weeks.
Three German Army Groups along with various other Axis military units who in total numbered over 4.3 million men, 3,3 million Germans and 1 million Axis, launched the invasion of the Soviet Union on June 22, 1941. Army Group North was deployed in East Prussia and was composed of 18th and 16th infantry armies and a Panzer Army, the 4th. Its main objectives were to secure the Baltic states and seize Leningrad. Opposite Army Group North were 2 Soviet Armies. The Germans threw their 600 Tanks at the junction of the two Soviet Armies in that sector. The 4th Panzer Army's objective was to cross the River Neman and River Dvina which were the two largest obstacles in route to Leningrad. On the first day, the Tanks crossed River Neman and penetrated 50 miles. Near Rasienai, the Panzers were counterattacked by 300 Soviet Tanks. It took 4 Days for the Germans to encircle and destroy the Soviet Tanks. The Panzers then crossed the River Dvina near Dvinsk. The Germans were now in striking distance of Leningrad; however, Hitler ordered the Panzers to hold their position while the Infantry Armies caught up. The orders to hold would last over a week, giving plenty of time to the Russians to shore up defenses around Leningrad. 
Army Group Center was deployed in Poland and comprised 9th, 4th Army, and two Panzer Armies, the 2nd and the 3rd. Its main objective was to capture Moscow. Opposite Army Group Center were 4 Soviet Armies. The Russians occupied a salient which jutted into German territory with its center at Bialystok. Beyond, Bialystok was Minsk which was a key railway junction and guardian of the main highway to Moscow. 3rd Panzer Army punched through the junction of the two Soviet Armies from the North and crossed the River Neman, and 2nd Panzer Army crossed the River Bug from the south. While the Panzers attacked, the Infantry armies struck at the Salient and encircled Russian troops at Bialystok. The Panzer Armies' objective was to meet at Minsk and prevent any Russian withdrawal. On June 27, 2nd and 3rd Panzer Armies met up at Minsk advancing 200 miles into Soviet Territory. In the vast pocket between Minsk and the Polish border, 32 Soviet Infantry and 8 Tank Divisions were encircled and were mercilessly attacked. Russian soldiers numbering 290,000 were captured, while 250,000 Russians managed to escape.
Army Group South was deployed in Southern Poland and Romania and was composed of 6th, 11th, and 17th armies and a Panzer Army, the 1st along with two Romanian Armies and several Italian, Slovakian and Hungarian Divisions. Its objective was to secure the oil fields of the Caucasus. In the South, the Russian Commanders had quickly reacted to the German attack and whose Tank forces vastly outnumbered the Germans. Opposite the Germans in the South were 3 Soviet Armies. The German struck at the junctions of the 3 Soviet Armies but 1st Panzer Army struck right through the Soviet Army with the objective of capturing Brody. On June 26, 5 Soviet Mechanized Corps with over 1,000 Tanks mounted a massive counterattack on 1st Panzer Army. The Battle was among the fiercest of the invasion lasting over 4 days. In the end the Germans prevailed but the Russians inflicted heavy losses on the 1st Panzer Army. With the failure of the Soviet Armored offensive, the last substantial Soviet tank forces in the south were now spent. 
On July 3, Hitler finally gave the go-ahead for the Panzers to resume their drive east after the infantry armies had caught up. The next objective of Army Group Center was the city of Smolensk which commanded the road to Moscow. Facing the Germans was an old Russian defensive line where the Soviets had deployed 6 Armies. On July 6, the Soviets launched an attack with 700 Tanks against the 3rd Panzer Army. The Germans, using their overwhelming air superiority, wiped out the Soviet tanks. The 2nd Panzer Army crossed the River Dneiper and closed on Smolensk from the south while 3rd Panzer Army after defeating the Soviet counter attack approached Smolensk from the north. Trapped between their pincers were 3 Soviet Armies. On July 26, the Panzers closed the gap and then began to eliminate the pocket which yielded over 300,000 Russian prisoners but 200,000 evaded capture. Hitler by now had lost faith in battles of encirclement and wanted to defeat the Soviets by inflicting severe economic damage which meant seizing the oil fields in the south and Leningrad in the North. Tanks from Army Group Center were diverted to Army Group North and South to aid them. Hitler's generals vehemently opposed this as Moscow was only 200 miles away from Army Group Center and the bulk of the Red Army was deployed in that sector and only an attack there could hope to end the war quickly. But Hitler was adamant and the Tanks from Army Group Center arrived and reinforced the 4th Panzer Army in the north which made it breakthrough the Soviet defenses on August 8 and by the end of August was only 30 miles from Leningrad. Meanwhile the Finns had pushed South East on both sides of Lake Ladoga reaching the old Finnish Soviet frontier.
In the South by mid-July below the Pinsk Marshes, the Germans had reached to a few miles of Kiev. The 1st Panzer Army then went South while the German 17th Army which was on 1st Panzer Army's southern flank struck east and in between the Germans trapped 3 Soviet Armies near Uman. As the Germans eliminated the pocket, the tanks turned north and crossed the Dneiper meanwhile 2nd Panzer Army which was diverted from Army Group Center on Hitler's orders had crossed the River Desna with 2nd Army on its right flank. The two Panzer armies now trapped 4 Soviet Armies and parts of two others. The encirclement of Soviet forces in Kiev was achieved on September 16. The encircled Soviets did not give up easily, a savage battle now ensued lasting for 10 days after which the Germans claimed over 600,000 Russian soldiers captured. Hitler called it the greatest battle in history. After Kiev, the Red Army no longer outnumbered the Germans and there were no more reserves. To defend Moscow, Stalin had only 800,000 men left.
On September 9, Army Group North reached to about 7 miles from Leningrad but Hitler ordered Leningrad to besieged. The Russians had mounted an increasing number of attacks against Army Group Center but lacking its tanks, it was in no position to go on the offensive. Hitler had changed his mind and decided that tanks will be send back to Army Group Center for its all out drive on Moscow. Operation Typhoon, the drive on Moscow began on October 2. In front of Army Group Center was a series of elaborate defense lines. The Germans easily penetrated the first defense line as 2nd Panzer Army returning from the south took Orel which was 75 miles behind the Russian first defense line. The Germans then pushed in and the vast pocket yielded 663,000 Russian prisoners. The Russians now had only 90,000 men and 1,500 tanks left for the defense for Moscow. 
Almost from the beginning of Operation Typhoon the weather had deteriorated steadily, slowing the German advance on Moscow to as little as 2 miles a day. On October 31, the Germany Army High Command ordered a halt on Operation Typhoon as the armies were re-organized. The pause gave the Soviets time to build up new armies and bring in the Soviet troops from the east as the neutrality pact signed by the Soviets and Japanese in April, 1941 assured Stalin that there was no longer a threat from the Japanese. 
On November 15, the Germans once again began the attack on Moscow. Facing the Germans were 6 Soviet Armies. The Germans intended to let the 3rd and 4th Panzer Armies cross the Moscow Canal and envelop Moscow from the North East. The 2nd Panzer Army would attack Tula and then close in on Moscow from the South and the 4th Army would smash in the center. However, on November 22, Soviet Siberian Troops were unleashed on the 2nd Panzer Army in the South which inflicted a shocking defeat on the Germans. The 4th Panzer Army succeeded in crossing the Moscow canal and on December 2 had penetrated to 15 miles of the Kremlin. But by then the first blizzards of the winter began and the Wehrmacht was not equipped for winter warfare. Frostbite and disease had caused more casualties than combat; dead and wounded had already reached 155,000 in 3 weeks. Strength of divisions were now at 50% and the bitter cold had caused severe problems for guns and equipment. Weather conditions grounded the Luftwaffe. Newly built up Soviet troops near Moscow now numbered over 500,000 men and Zhukov on December 5 launched a massive counter attack which pushed the Germans back over 200 miles but no decisive breakthrough was achieved. The invasion of the Soviet Union had so far cost the Germans over 250,000 dead, 500,000 wounded and most of their tanks.
===The Pacific (April 1941 – June 1943)===
Hitler kept his plan to invade the USSR secret from the Japanese. The USSR, fearing a two-front war, decided to make peace with Japan. On April 13, 1941, the USSR and Japan signed the Soviet-Japanese Neutrality Pact, thus allowing the Japanese to concentrate their attention to the upcoming war in Asia-Pacific.
In the summer of 1941, the United States, the United Kingdom, and the Netherlands began an oil embargo against Japan, threatening its ability to fight a major war at sea or in the air. However, Japanese forces continued to advance into China. Japan planned an attack on Pearl Harbor to cripple the U.S. Pacific Fleet, then seize oil fields in the Dutch East Indies.
On December 7, Japan launched virtually simultaneous surprise attacks against Pearl Harbor, Thailand and on the British territories of Malaya and Hong Kong. A Japanese carrier fleet launched an unexpected air attack on Pearl Harbor. The raid destroyed most of the American aircraft on the island and knocked the main American battle fleet out of action (three battleships were sunk, and five more were heavily damaged, though only USS Arizona and USS Oklahoma were permanently lost, the other six battleships were repaired and eventually returned to service). However, the four American aircraft carriers that had been the intended main target of the Japanese attack were off at sea. At Pearl Harbor, the main dock, supply, and repair facilities were quickly repaired. Furthermore, the base's fuel storage facilities, whose destruction could have crippled the Pacific fleet, were untouched. The attack united American public opinion to demand vengeance against Japan. The following day, December 8, the United States declared war on Japan.
Simultaneously with the attack on Hawaii, the Japanese attacked Wake Island, an American territory in the central Pacific. The initial landing attempt was repulsed by the garrison of Marines, and fierce resistance continued until December 23. The Japanese sent heavy reinforcements, and the garrison surrendered when it became clear that no American relief force was coming.
Japan also invaded the Philippines, a U.S. Commonwealth, on December 8. American and Filipino forces, under General Douglas MacArthur, were forced to retreat to the Bataan Peninsula. Dogged resistance continued until April, buying precious time for the Allies. Following their surrender, the survivors were led on the Bataan Death March. Allied resistance continued for an additional month on the island fortress of Corregidor, until it too surrendered. General MacArthur, who had been ordered to retreat to Australia, vowed, "I shall return."
Disaster struck the British on December 10, as they lost two major battleships, HMS Prince of Wales and HMS Repulse. Both ships had been attacked by 85 Japanese bombers and torpedo planes based in Saigon, and 840 UK sailors perished. Churchill was to say of the event, "In all of the war I have never received a more direct shock."
Germany declared war on the United States on December 11, even though it was not obliged to do so under the Tripartite Pact. Hitler hoped that Japan would support Germany by attacking the Soviet Union. Japan did not do so because it had signed a non-aggression treaty, preferring instead to focus on expanding its empire in China, Southeast Asia, and the Pacific. Rather than opening a second front on the USSR, the effect of Germany's declaration of war was to remove any significant opposition within the United States to joining the fight in the European Theater.
The Allies were officially formed in the Declaration by United Nations on January 1, 1942. Soon afterwards, the American-British-Dutch-Australian Command (ABDACOM) was formed to unite Allied forces in South East Asia. It was the first Allied supreme command of the war.
 
ABDACOM naval forces were all but destroyed in the Battle of the Java Sea—the largest naval battle of the war up that point—on February 28 through March 1. The joint command was wound up shortly afterwards, to be replaced by three Allied supreme commands in southern Asia and the Pacific.
In April, the Doolittle Raid, the first Allied air raid on Tokyo, boosted morale in the United States and caused Japan to shift resources to homeland defense, but did little physical damage.
In early May, the Japanese implemented Mo Sakusen (Operation Mo), a plan to take Port Moresby, New Guinea. The first stage was thwarted by the U.S. and Australian navies in the Battle of the Coral Sea. This was both the first battle fought between aircraft carriers, and the first battle where the opposing fleets never made direct visual contact. The American aircraft carrier Lexington was sunk and the Yorktown was severely damaged, while the Japanese lost the light carrier Shōhō and the large carrier Shōkaku suffered moderate damage. Zuikaku lost half of her air complement, and along with Shōkaku, was unable to participate in the upcoming battle at Midway. The battle was a tactical victory for the Japanese, as they inflicted heavier losses on the American fleet, but it was a strategic American victory, as the Japanese attack on Port Moresby was deflected.
In the six months after Pearl Harbor the Japanese had achieved nearly all of their naval objectives. Their fleet of eleven battleships, ten carriers, eighteen heavy and twenty light cruisers remained relatively intact. They had seriously damaged or sunk all U.S. battleships in the Pacific. The British and Dutch Far Eastern fleets had been destroyed, and the Royal Australian Navy had been driven back to port.Keegan, John. The Second World War. 1989. p267. Their ring of conquests settled on a defensive perimeter of their choosing, extending from the Central Pacific to New Guinea to Burma.
Opposing this, the only significant strategic force remaining to the Allies was the naval base at Pearl Harbor, including the U.S. Pacific Fleet's three aircraft carriers. Both sides viewed a decisive battle between aircraft carriers as inevitable, and the Japanese were confident in that they held a numerical advantage in heavy carriers of 10:3.Keegan, John. The Second World War. p268. They also had an excellent carrier-based aircraft in the Zero. The Japanese sent a task force towards Midway Island, an outlier of the Hawaiian Islands, with the goal of drawing the remainder of the American fleet to battle. On June 5, American carrier-based dive-bombers sighted the Japanese force and sank four of Japan's best aircraft carriers in the Battle of Midway, at the cost of the carrier Yorktown. This was a major victory for the United States, and marked the turning point of the war in the Pacific. American shipbuilding and aircraft production vastly outpaced the Japanese, and the Japanese fleet would never again enjoy such numerical superiority. 
In July, the Japanese attempted to take Port Moresby by land, along the Kokoda Track, a rugged, single-file path through the jungle and mountains. An outnumbered, untrained and ill-equipped Australian battalion—awaiting the return of regular units from North Africa and the U.S. Army—waged a fighting retreat against a 5,000-strong Japanese force. 
On August 7, U.S. Marines began the Battle of Guadalcanal. For the next six months, U.S. forces fought Japanese forces for control of the island. Meanwhile, several naval encounters raged in the nearby waters, including the Battle of Savo Island, Battle of Cape Esperance, Naval Battle of Guadalcanal, and Battle of Tassafaronga.
In late August and early September, while battle raged on the Kokoda Track and Guadalcanal, an attack by Japanese marines at the eastern tip of New Guinea was defeated by Australian forces, in the Battle of Milne Bay. This was the first defeat for Japanese land forces during the Pacific War.
On January 22, after a bitter battle at Gona and Buna, Australian and U.S. forces took back the major Japanese beachheads in eastern New Guinea.
American authorities declared Guadalcanal secure on February 9. U.S., New Zealand, Australian and Pacific Island forces undertook the prolonged campaign to retake the occupied parts of the Solomon Islands, New Guinea, and the Dutch East Indies, experiencing some of the toughest resistance of the war. The rest of the Solomon Islands were retaken in 1943.
===China and South-East Asia (September 1941 – March 1944)===
By 1940, the war had reached a stalemate with both sides making minimal gains. The United States provided heavy financial support for China and set up the Flying Tigers air unit to bolster Chinese air forces.
Japanese forces invaded northern parts of French Indo-China on September 22. Japanese relations with the west had deteriorated steadily in recent years and United States, having renounced the U.S.-Japanese trade treaty of 1911, placed embargoes on exports to Japan of war and other materials.
Less than 24 hours after the Attack on Pearl Harbor, Japan invaded Hong Kong. The Philippines and the British colonies of Malaya, Borneo, and Burma soon followed, with Japan's intention of seizing the oilfields of the Dutch East Indies. Despite fierce resistance by Philippine, Australian, New Zealand, British, Canadian, Indian, and American forces, all these territories capitulated to the Japanese in a matter of months. Singapore fell to the Japanese on February 15. Approximately 80,000 British Commonwealth personnel (along with 50,000 taken in Malaya), went into Japanese POW camps, representing the largest-ever surrender of British-led personnel. Churchill considered the British defeat at Singapore as one of the most humiliating British defeats of all time.
Japan launched a major offensive in China following the attack on Pearl Harbor. The aim of the offensive was to take the strategically important city of Changsha, which the Japanese had failed to capture on two previous occasions. For the attack, the Japanese massed 120,000 soldiers under four divisions. The Chinese responded with 300,000 men, and soon the Japanese army was encircled and had to retreat.
The Chinese Nationalist Kuomintang Army, under Chiang Kai-shek, and the Communist Chinese Army, under Mao Zedong, both opposed the Japanese occupation of China, but never truly allied against the Japanese. Conflict between Nationalist and Communist forces emerged long before the war; it continued after and, to an extent, even during the war, though less openly. 
The Japanese had captured most of Burma, severing the Burma Road by which the Western Allies had been supplying the Chinese Nationalists. This loss forced the Allies to create a large sustained airlift from India, known as "flying the Hump". Under the American General Joseph Stilwell, Chinese forces in India were retrained and re-equipped, while preparations were made to drive the Ledo Road from India to replace the Burma Road. This effort was to prove an enormous engineering task.
===The Atlantic (September 1939 - May 1945)===
In the North Atlantic, German U-boats attempted to cut supply lines to the United Kingdom by sinking merchant ships. In the first four months of the war they sank more than 110 vessels. In addition to supply ships, the U-boats occasionally attacked British warships. One U-boat sank the British carrier HMS Courageous, while another managed to sink the battleship HMS Royal Oak in her home anchorage of Scapa Flow.
In addition to U-boats, surface raiders posed a threat to Allied shipping. In the South Atlantic, the German pocket battleship Admiral Graf Spee sank nine British Merchant Navy vessels. She was tracked down off the coast of South America, then engaged by the cruisers HMS Ajax, HMS Exeter, and HMNZS Achilles in the Battle of the River Plate, and forced into Montevideo Harbor. Rather than face battle again, Captain Langsdorff made for sea and scuttled his battleship just outside the harbor.
On May 24, 1941, the German battleship Bismarck left port, threatening to break out into the Atlantic. She sank HMS Hood, one of the finest battlecruisers in the Royal Navy. A massive hunt ensued, in which the German battleship was sunk after a 1,700-mile (2,700 kilometer) chase, during which the British employed eight battleships and battle cruisers, two aircraft carriers, 11 cruisers, 21 destroyers, and six submarines. Fairey Swordfish torpedo bombers from aircraft carrier HMS Ark Royal struck the Bismarck, causing her rudder to jam and allowing the pursuing Royal Navy squadrons to sink her.
In the summer of 1941, the Soviet Union entered the war on the side of the Allies. While they had tremendous reserves in manpower, they had lost much of their equipment and manufacturing base in the first few weeks following the German invasion. The Western Allies attempted to remedy this by sending Arctic convoys, which travelled from the United Kingdom and the United States to the northern ports of the Soviet Union - Archangel and Murmansk. The treacherous route around the North Cape of Norway was the site of many battles as the Germans continually tried to disrupt the convoys using U-boats, bombers, and surface ships.
Following the entry of the United States into the war in December 1941, U-boats sank shipping along the East Coast of the United States and Canada, the waters around Newfoundland, the Caribbean Sea, and the Gulf of Mexico. They were initially so successful that this became known among U-boat crews as the Second happy time. Eventually, the institution of shore blackouts and an interlocking convoy system resulted in a drop in attacks and U-boats shifted their operations back to the mid-Atlantic.
On May 9, 1942 the destroyer HMS Bulldog captured a German U-Boat and recovered a complete, intact Enigma Machine, an encryption device. The machine was taken to Bletchley Park, England, where it was used to break the German code. Thereafter the Allies enjoyed an advantage in that they could intercept and understand some German radio communications, directing naval forces to where they would be most effective.
In December 1943, the last major sea battle between the Royal Navy and the German Navy took place. At the Battle of North Cape, Germany's last battlecruiser, the Scharnhorst, was sunk by HMS Duke of York, HMS Belfast, and several destroyers.
The turning point of the Battle of the Atlantic took place in early 1943 as the Allies refined their naval tactics, effectively making use of new technology to counter the U-Boats. The Allies produced ships faster than they were sunk, and lost fewer ships by adopting the convoy system. Improved anti-submarine warfare meant that the life expectancy of a typical U-boat crew would be measured in months. The vastly improved Type 21 U-boat appeared as the war was ending, but too late to affect the outcome.
===The Eastern Front (January 1942 - February 1943)===
On January 6, 1942, Stalin, confident of his earlier victory, ordered a general counter-offensive. Initially the attacks made good ground as Soviet pincers closed around Demyansk and Vyazma and threatening attacks were made towards Smolensk and Bryansk. But despite these successes the Soviet offensive soon ran out of steam. By March, the Germans had recovered and stabilized their line and secured the neck of the Vyazma Pocket. Only at Demyansk was there any serious prospect of a major Soviet victory. Here a large part of the German 16th Army had been surrounded. Hitler ordered no withdrawal and the 92,000 men trapped in the pocket were to hold their ground while they were re-supplied by air. For 10 weeks they held out until April when a land corridor was opened to the west. The German forces retained Demyansk until they were permitted to withdraw in February 1943. 
With the spring both sides decided to resume the offensive. While the German high command decided to stabilize the front at Kharkov, the Soviets unknowingly decided to attack in the same sector to maintain pressure in the south. The Soviets had attacked in Kharkov sector in January and had established a salient on the West Bank of the River Donets. On May 12, the Soviets opened with concentric attacks on either side of Kharkov and in both sides the Soviets broke through German lines and a serious threat to the city emerged. In response, the Germans accelerated the plans for their own offensive and launching it 5 days later.
The German 6th Army struck at the salient from the south and encircled the entire Soviet army assaulting Kharkov. In the last days of May, the Germans destroyed the forces inside the pocket. Of the Soviet troops inside the pocket, 70,000 were killed, 200,000 captured and only 22,000 managed to escape. The Germans did not realize the scale of the victory they had achieved, and unknown to the Germans, by early June the wide steppes of the Caucuses lay virtually undefended.
Hitler had by now realized that his Armies were too weak to carry out an offensive on all sectors of the Eastern Front. But if the Germans could seize the oil and fertile rich area of Southern Russia this would give the Germans the means to continue with the war. In April, Hitler outlined his plans for the main campaign in Russia codenamed Operation Blue. The overall objective of Operation Blue would be the destruction of the Red Army's southern front, consildation of the Ukraine west of the River Volga, and the capture of the Caucaus oil fields. The Germans reinforced Army Group South by transferring divisions from other sectors and getting divisions from Axis allies. By late June, Hitler had 74 Divisions ready to go on the offensive, 54 of them were German.
The German plan was a three pronged attack in Southern Russia. The 4th Panzer Army (transferred from Army Group North) and the 2nd Army supported by the 2nd Hungarian Army would attack from Kursk to Voronezh and afterwhich they will continue to attack and anchor their left wing around the River Volga. The 6th Army would attack from Kharkov and move in parallel with 4th Panzer Army to reach the River Volga. The 1st Panzer Army would strike towards the lower Don River, flanked on its right by the 17th Army. These movements were expected to result in a series of great encirclements of Soviet troops. The Soviets did not know where the main German offensive of 1942 would come. Stalin was convinced that the German objective of 1942 would be Moscow and over 50% of all Red Army troops were deployed in the Moscow region. Only 10% of Russian troops were deployed in Southern Russia.
On June 28, 1942, the German offensive began. Everywhere the Russians fell back as the Germans sliced through the Russian defenses. By July 5, forward elements of 4th Panzer Army reached the River Don near Voronezh and got embroiled in a bitter battle to capture the city. The Russians, by tying down 4th Panzer Army gained vital time to reinforce their defenses. The Russians for the first time in the war were not fighting to hold hopelessly exposed positions but were retreating in good order. As German pincers closed in they only found stragglers and rear guards. Angered by the delays, Hitler re-organized Army Group South to two smaller Army Groups, Army Group A which now included the 17th Army, 1st Panzer Army and 4th Panzer Army. Army Group B included 2nd Army, 6th Army and two Italian and Hungarian Armies. The bulk of the Armored forces were now concentrated with Army Group A which was ordered to attack towards the Caucasus oil fields while Army Group B was ordered to capture Stalingrad and guard against any Soviet counter attacks. The transfer of 4th Panzer Army away from 6th Army to help the 1st Panzer Army cross the lower region of the Don River reduced 6th Army's advance to a march giving further time to the Russians to consolidate their positions. 
By July 23, the German 6th Army had taken Rostov but Russians fought a skillful rearguard action which embroiled the Germans in heavy urban fighting to take the city. This also allowed the main Russian formations to escape encirclements. With the River Don's crossing secured in the south and with the 6th Army's advance flagging, Hitler send the 4th Panzer Army back to join up with 6th Army. In late July, 6th Army resumed its offensive and by August 10, 6th Army cleared Russian presence from the west bank of the River Don but Russians held out in some areas further delaying 6th Army's march east. In contrast, Army Group A after crossing the River Don on July 25 had fanned out on a broad front. The German 17th Army swung west towards the Black Sea, the 1st Panzer Army attacked towards the south and east sweeping through country largely abandoned by the Russians. On August 9, 1st Panzer Army reached the foothills of the Caucasus mountains, advancing more than 300 miles.
The German 6th Army after finally clearing the west bank of the River Don of Russian troops crossed the river on August 21 and began advancing on Stalingrad. Germans bombed the city killing over 40,000 people and turning much of the city into rubble. The 6th Army's advance on Stalingrad from the North while the 4th Panzer Army advanced from the South. Between these armies and in the area from River Don to River Volga, a salient had been created. Two Russian Armies were in the salient and on August 29, 4th Panzer Army mounted a major attack through the salient towards Stalingrad. 6th Army was ordered to do the same but Russians mounted major attacks against 6th Army from the North which tied up 6th Army for 3 vital days enabling the Soviet forces in the salient to escape encirclement and fall back towards Stalingrad. The Russians who by now had realized that the German plan was the seizure of the oil fields began sending large number of troops from the Moscow sector to reinforce their troops in the South. Zhukov assumed command of the Stalingrad front and in early September and mounted a series of attacks from the North which further delayed the 6th Army's attempt to seize Stalingrad. By mid-September, the 6th Army after neutralizing the Soviet counterattacks once again resumed to capture the city. On September 13, the Germans advanced through the southern suburbs and by September 23, 1942, the main factory complex was surrounded and the German artillery was within range of the quays on the river, across which the Soviets evacuated wounded and brought in reinforcements. Ferocious street fighting, hand-to-hand conflict of the most savage kind, now ensued at Stalingrad. Exhaustion and deprivation gradually sapped men's strength. Hitler, who had become obsessed with the battle of Stalingrad, refused to countenance a withdrawal. General Paulus, in desperation, launched yet another attack early in November by which time the Germans had managed to capture 90% of the city. The Soviets, however, had been building up massive forces on the flanks of Stalingrad which were by this time severely undermanned as the bulk of the German forces had been concentrated in capturing the city and Axis satellite troops were left guarding the flanks. The Soviets launched Operation Uranus on November 19 1942, with twin attacks that met at the city of Kalach four days, encircling the 6th Army in Stalingrad.
The Germans requested permission to attempt a breakout, which was refused by Hitler, who ordered the Sixth Army to remain in Stalingrad where he promised they would be supplied by air until rescued. About the same time, the Soviets launched Operation Mars in a salient near the vicinity of Moscow. Its objective was to tie down Army Group Center and to prevent it from reinforcing Army Group South at Stalingrad.
Meanwhile, Army Group A's advance into the Caucasus had stalled as Russians had destroyed the oil production facilities and a year's work was required to bring them back up and the remaining oil fields lay south of the Caucasus Mountains. Throughout August and September, German Mountain troops probed for a way through but by October with the onset of winter, they were no closer to their objective. With German troops encircled in Stalingrad, Army Group A began to fall back. 
By December, Field Marshal von Manstein hastily put together a German relief force of units composed from Army Group A to relieve the trapped Sixth Army. Unable to get reinforcements from Army Group Center, the relief force only managed to get within 50 kilometers (30 mi) before they were turned back by the Soviets. By the end of the year, the Sixth Army was in desperate condition, as the Luftwaffe was able to supply only about a sixth of the supplies needed.
Shortly before surrendering to the Red Army on February 2 1943, Friedrich Paulus was promoted to Field Marshal. This was a message from Hitler, because no German Field Marshal had ever surrendered his troops or been taken alive. Of the 300,000 strong 6th Army, only 91,000 survived to be taken prisoner, including 22 generals, of which only 5,000 men ever returned to Germany after the war. This was to be the greatest, and most costly, battle in terms of human life in history. Around 2 million men were killed or wounded on both sides, including civilians, with Axis casualties estimated to be approximately 850,000 and 750,000 for the Soviets.
===The Western Front (September 1940 – June 1944)===
Apart from Italy, Western Europe saw very little fighting from September 1940-June 1944. British and Canadian forces launched a small raid on the occupied French seaport of Dieppe, on August 19, 1942, whose aim was to test and gain information for an invasion of Europe which would happen later in the war. The Dieppe Raid was a total disaster but it provided critical information about amphibious tactics which would be utilized later in Operation Torch and Operation Overlord.
In December 1941, following the Japanese attack on Pearl Harbor which brought the United States into the war, Churchill and Roosevelt met at the Arcadia Conference. They agreed that defeating Germany had priority over defeating Japan. To relieve German pressure on the Soviet Union, the United States proposed a 1942 cross-channel invasion of France. The British opposed this, suggesting instead a small invasion of Norway or landings in French North Africa. The Declaration by the United Nations was issued, and the Western Allies invaded North Africa first.
With the entry of the United States into the War, the aerial war turned in favor of the Allies by late 1942. The U.S. air force began the first daylight bombing of Germany, which allowed far more precise targeting, but exposed the bombers to more danger than night bombing. Meanwhile the British and the Canadians targeting German cities and war industries for night bombing. This effort was orchestrated by Air Chief Marshall Harris, who became known as "Bomber Harris". Additionally, Winston Churchill ordered "terror raids" intended to wipe out whole cities in one go, by incendiary devices causing firestorms, thus depriving German workers of their homes. Mass raids involving upwards of 500 to 1000 heavy bombers at a time were undertaken against airfields, industrial centers, submarine bases, rail-marshalling yards, oil depots and, in the later stages of the war, launching sites for weapons such as the V-1 missile (nicknamed 'doodlebug'), the V-2 rocket and a jet-engined plane, the Messerschmitt Me 262. The Luftwaffe was overwhelmed and by 1945, all major German cities were burnt-out ruins. 
The Allies also began sabotage missions against Germany such as Operation Anthropoid in which Reinhard Heydrich, the architect of the Final Solution was assassinated in May 1942 by Czech resistance agents flown in from the United Kingdom. Hitler ordered severe reprisals against the occupants of the nearby Czechoslovakian village of Lidice. All the while, the Allies continued to build up their forces in the United Kingdom for an eventual invasion of Western Europe which was planned for late spring or early summer of 1944.
===The Mediterranean (May 1943 – March 1945)===
The surrender of Axis forces in Tunisia on May 13, 1943, yielded some 250,000 prisoners. The North African war proved to be a disaster for Italy, and when the Allies invaded Sicily on July 10 in Operation Husky, capturing the island in a little over a month, the regime of Benito Mussolini collapsed. On July 25, he was removed from office by Victor Emmanuel III, the King of Italy, and arrested with the positive consent of the Great Fascist Council. A new government, led by Pietro Badoglio, took power and declared ostensibly that Italy would stay in the war. Badoglio had already begun secret peace negotiations with the Allies.
The Allies invaded mainland Italy on September 3, 1943. Italy surrendered to the Allies on September 8, as had been agreed in negotiations. The royal family and Badoglio government escaped to the south, leaving the Italian army without orders, while the Germans took over the fight, forcing the Allies to a complete halt in the winter of 1943–44 at the Gustav Line south of Rome.
In the north, Mussolini, with Nazi support, created what was effectively a puppet state, the Italian Social Republic or Republic of Salò, named after the new capital of Salò on Lake Garda.
In May and June 1943 the main corps of the Yugoslav Partisan was encircled and nearly annihilated by German forces in the Sutjeska offensive in eastern Bosnia. The core forces around Tito successfully broke through the encirclement, and the tide turned in their favor. After Italy capitulated, the guerillas took and held on to several Adriatic islands, notably Vis, which became an Allied air force base. At the Tehran Conference the Allies recognized the Partisans as the legitimate Yugoslav fighting force.
Following Italy's surrender, German troops took over the defense of the Italian peninsula and established the Gustav line in the southern Apennine Mountains south of Rome. The Allies were unable to break this line, and so attempted to bypass it with an amphibious landing at Anzio on January 22, 1944. The landing, named Operation Shingle, quickly became encircled by the Germans and bogged down, leading Churchill to comment, "Instead of hurling a wildcat onto the shore all we got was a stranded whale."
Unable to circumvent the Gustav line, the Allies again attempted to break through with frontal assaults. On February 15, the monastery of Monte Cassino, founded in 524 by St. Benedict was destroyed by American B-17 and B-26 bombers. Crack German paratroopers poured back into the ruins to defend it. From January 12 to May 18, it was assaulted four times by Allied troops, for a loss of over 54,000 Allied and 20,000 German soldiers.
After months, the Gustav line was broken and the Allies marched north. On June 4, Rome was liberated, and the Allied army reached Florence in August. It then was held at the Gothic Line on the Tuscan Apennines during the winter.
As the Red Army advanced into the Balkans, Romania left the Axis on August 23, Bulgaria on September 9, and German troops abandoned Greece on October 12. Concurrently, Yugoslav Partisans shifted operations into Serbia, freed Belgrade on October 20 with Soviet help, and assisted the Albanian Resistance rout the Germans by November 29. By year end, the Partisans controlled the eastern half of Yugoslavia and the Dalmatian coast, and on March 20, 1945 they mounted their final push westwards.
===The Eastern Front (February 1943 – January 1945)===
After the surrender of the German Sixth Army at Stalingrad on February 2, 1943, the Red Army launched eight offensives during the winter. Many were concentrated along the Don basin near Stalingrad. These attacks resulted in initial gains until German forces were able to take advantage of the over extended and weakened condition of the Red Army and launch a counter attack to re-capture the city of Kharkov and surrounding areas. This was to be the last major strategic German victory of World War II.
The rains of spring inhibited campaigning in the Soviet Union, but both sides used the interval to build up for the inevitable battle that would come in the summer. The start date for the offensive had been moved repeatedly as delays in preparation had forced the Germans to postpone the attack. By July 4, the Wehrmacht, after assembling their greatest concentration of firepower during the whole of World War II, launched their offensive against the Soviet Union at the Kursk salient. Their intentions were known by the Soviets, who hastened to defend the salient with an enormous system of earthwork defenses. The Germans attacked from both the north and south of the salient and hoped to meet in the middle, cutting off the salient and trapping 60 Soviet divisions. The German offensive in the Northern sector was ground down as little progress was made through the Soviet defenses but in the Southern Sector there was a danger of a German breakthrough. The Soviets then brought up their reserves to contain the German thrust in the Southern sector, and the ensuing Battle of Kursk became the largest tank battle of the war, near the city of Prokhorovka. The Germans lacking any sizable reserves had exhausted their armored forces and could not stop the Soviet counteroffensive that threw them back across their starting positions.
The Soviets captured Kharkov following their victory at Kursk and with the Autumn rains threatening, Hitler agreed to a general withdrawal to the Dnieper line in August. As September proceeded into October, the Germans found the Dnieper line impossible to hold as the Soviet bridgeheads grew. Important Dnieper towns started to fall, with Zaporozhye the first to go, followed by Dnepropetrovsk. Early in November the Soviets broke out of their bridgeheads on either side of Kiev and recaptured the Ukrainian capital. The 1st Ukrainian Front attacked at Korosten on Christmas Eve, and the Soviet advance continued along the railway line until the 1939 Soviet-Polish border was reached.
The Soviets launched their winter offensive in January 1944 in the Northern sector and relieved the brutal siege of Leningrad. The Germans conducted an orderly retreat from the Leningrad area to a shorter line based on the lakes to the south. By March the Soviets struck into Romania from Ukraine. The Soviet forces encircled the First Panzer Army north of the Dniestr river. The Germans escaped the pocket in April, saving most of their men but losing their heavy equipment. During April, the Red Army launched a series of attacks near the city of Iaşi, Romania, aimed at capturing the strategically important sector which they hoped to use as a springboard into Romania for a summer offensive. The Soviets were held back by the German and Romanian forces when they launched the attack through the forest of Târgul Frumos as Axis forces successfully defended the sector through the month of April. 
As Soviet troops neared Hungary, German troops occupied Hungary on March 20. Hitler thought that Hungarian leader Admiral Miklós Horthy might no longer be a reliable ally. Germany's other Axis ally, Finland had sought a separate peace with Stalin in February 1944, but would not accept the initial terms offered. On June 9, the Soviet Union began the Fourth strategic offensive on the Karelian Isthmus that, after three months, forced Finland to accept an armistice.
Before the Soviet could begin their Summer offensive into Belarus they had to clear the Crimea peninsula of Axis forces. Remnants of the German Seventeenth Army of Army Group South and some Romanian forces were cut off and left behind in the peninsula when the Germans retreated from the Ukraine. In early May, the Red Army's 3rd Ukrainian Front attacked the Germans and the ensuing battle was a complete victory of the Soviet forces and a botched evacuation effort across the Black Sea by Germany failed.
With the Crimea cleared, the long awaited Soviet summer offensive codenamed, Operation Bagration, began on June 22, 1944 which involved 2.5 million men and 6,000 tanks. Its objective was to clear German troops from Belarus and crush German Army Group Center which was defending that sector. The offensive was timed to coincide with the Allied landings in Normandy but delays caused the offensive to be postponed for a few weeks. The subsequent battle resulted in the destruction of German Army Group Centre and over 800,000 German casualties, the greatest defeat for the Wehrmacht during the war. The Soviets swept forward, reaching the outskirts of Warsaw on July 31.
The proximity of the Red Army led the Poles in Warsaw to believe they would soon be liberated. On August 1, they revolted as part of the wider Operation Tempest. Nearly 40,000 Polish resistance fighters seized control of the city. The Soviets, however, did not advance any further. The only assistance given to the Poles was artillery fire, as German army units moved into the city to put down the revolt. The resistance ended on October 2. German units then destroyed most of what was left of the city.
Following the destruction of German Army Group Center, the Soviets attacked German forces in the south in mid-July 1944, and in a month's time they cleared Ukraine of German presence inflicting heavy losses on the Germans. Once Ukraine had been cleared the Soviet forces struck into Romania. The Red Army's 2nd and 3rd Ukrainian Fronts engaged German Heeresgruppe Südukraine, which consisted of German and Romanian formations, in an operation to occupy Romania and destroy the German formations in the sector. The result of the Battle of Romania was a complete victory for the Red Army, and a switch of Romania from the Axis to the Allied camp. Bulgaria surrendered to the Red Army in September. Following the German retreat from Romania, the Soviets entered Hungary in October 1944 but the German Sixth Army encircled and destroyed three corps of Marshal Rodion Yakovlevich Malinovsky's Group Pliyev near Debrecen, Hungary. The rapid assault the Soviets had hoped that would lead to the capture of Budapest was now halted and Hungary would remain Germany's ally until the end of the war in Europe. This battle would be the last German victory in the Eastern Front.
The Soviets recovered from their defeat in Debrecen and advancing columns of the Red Army liberated Belgrade in late December and reached Budapest on December 29, 1944 and en-circled the city where over 188,000 Axis troops were trapped including many German Waffen-SS. The Germans held out till February 13, 1945 and the siege became one of the bloodiest of the war. Meanwhile the Red Army's 1st, 2nd, and 3rd Baltic Fronts engaged the remnants of German Army Group Center and Army Group North to capture the Baltic region from the Germans in October 1944. The result of the series of battles was a permanent loss of contact between Army Groups North and Centre, and the creation of the Courland Pocket in Latvia where the 18th and 16th German Armies, numbering over 250,000 men were trapped and would remain there till the end of the war.
===The Pacific (June 1943 – July 1945)===
Battle of Iwo Jima|Battle of Okinawa}}
On June 30, the Allies launched Operation Cartwheel, a grand strategy for the South and South West Pacific, aimed at isolating the major Japanese base at Rabaul, before proceeding on an "island-hopping" campaign towards Japan. Three main objectives were identified: recapturing Tulagi and the Santa Cruz Islands; recapturing the north coast of New Guinea, and the central Solomon Islands and; the reduction of Rabaul and related bases. 
By September, Australian and U.S. forces in New Guinea had captured the major Japanese bases at Salamaua and Lae. Soon afterwards they launched the Huon Peninsula, the Finisterre Range, Bougainville, and New Britain campaigns.
In November, U.S. Marines won the Battle of Tarawa. This was the first heavily opposed amphibious assault in the Pacific theater. The high casualties taken by the Marines sparked off a storm of protest in the United States, where the large losses could not be understood for such a tiny and seemingly unimportant island. The Allies adopted a policy of bypassing some Japanese island strongholds and letting them "wither on the vine", cut off from supplies and troop reinforcements.
The Allied advance continued in the Pacific with the capture of the Marshall Islands before the end of February. Some 42,000 U.S. Army soldiers and U.S. Marines landed on Kwajalein atoll on January 31. Fierce fighting occurred, and the island was taken on February 6. U.S. Marines next defeated the Japanese in the Battle of Eniwetok.
The U.S. strategic objective was to gain airbases within bombing range of the new B-29s on the Mariana Islands, especially Saipan, Tinian and Guam. On June 11, the U.S. Naval fleet bombarded Saipan, defended by 32,000 Japanese troops; 77,000 Marines landed starting the 15th, and the island was secure by July 9. The Japanese committed much of their declining naval strength in the Battle of the Philippine Sea, but suffered severe losses in both ships and aircraft. After the battle, the Japanese aircraft carrier force was no longer militarily effective. With the capture of Saipan, Japan was finally within range of B-29 bombers.
Guam was invaded on July 21 and taken on August 10, but the Japanese fought fanatically. Mopping-up operations continued long after the Battle of Guam was officially over. The island of Tinian was invaded on July 24 and was conquered on August 1. This operation saw the first use of napalm in the war.
thumb|right|"I have returned." — A famous photo of Gen. MacArthur coming ashore back to the Philippines. Photo taken by Carl Mydans of Life magazine.
General MacArthur's troops liberated the Philippines, landing on the island of Leyte on October 20. The Japanese had prepared a rigorous defense and used the last of their naval forces in a failed attempt to destroy the invasion force in the Battle of Leyte Gulf, October 23 through October 26, 1944, arguably the largest naval battle in history. This was the first battle that employed Japanese kamikaze attacks. The Japanese battleship Musashi, one of the two largest battleships ever built, was sunk by 19 American torpedoes and 17 bombs. 
Throughout 1944, Allied submarines and aircraft attacked Japanese merchant shipping and deprived Japan's industry of the raw materials it had gone to war to obtain. The main target was oil, and Japan ran almost dry by late 1944. In 1944, submarines sank over two million tons of cargo, while the Japanese were only able to replace less than one million tons.
for emergency landings for B29s and because it was close enough 
In January 1945, the U.S. Sixth Army landed on Luzon, the main island of the Philippines. Manila was recaptured by March. 
The United States captured Iwo Jima in February. The island was psychologically important because it was traditional Japanese territory, administered by the Tokyo prefecture. It was heavily defended with many underground entrenchments, but was eventually taken by Marines after they captured Mount Suribachi, a keystone of the defense. Iwo Jima proved invaluable because of its two airfields that were used for emergency landings for B29's, and because it was close enough to provide fighter escort that could reach the Japanese Home Islands.Yoder, Dan. The Fight for Iwo Jima. In History of the Second World War. editor Sir Basil Hart. 1989. p393. 
With the subsequent capture of Okinawa (April through June), the U.S. brought the Japanese homeland within easier range of naval and air attack. The Japanese defended the island with ground forces, kamikazes, and with the one-way suicide mission of the battleship Yamato, which was sunk by American dive-bombers. Amongst dozens of other Japanese cities, Tokyo was firebombed, and about 90,000 people died from the initial attack. The dense living conditions around production centres and the wooden residential constructions contributed to the large loss of life. In addition, the ports and major waterways of Japan were extensively mined by air in Operation Starvation, which seriously disrupted the logistics of the island nation. 
The last major offensive in the South West Pacific Area was the Borneo campaign of mid-1945, which was aimed at further isolating the remaining Japanese forces in Southeast Asia and securing the release of Allied prisoners of war.
===China and South-East Asia (March 1944 – June 1945)===
In April 1944, the Japanese launched Operation Ichigo, to secure the railway route from Peking to Nanking, and to clear southern China of American airfields under the command of General Chennault Keegan, John. The Second World War. 1989. p548. The operation was successful in that it opened a continuous corridor from Peking to Indochina, and the airfields were forced to relocate inland. However it failed to destroy the army of Chiang Kai-shek, and the Americans soon acquired the Marianas, from which they could bomb the Japanese Home Islands.
While the Americans steadily built the Ledo Road from India to China, in March 1944, the Japanese began their own offensive into India. This "Delhi Chalo" ('March to Delhi') was initiated by Netaji Subhas Chandra Bose,Peter Ward Fay The Forgotten Army: India's Armed Struggle for Independence 1941-45 the commander of Indian National Army (a force comprised of POWs from the British Indian Army who had been captured by the Japanese and had decided to join the war in an attempt to rid India of their colonial rulers, and thereby attain independence).Modern India by Sumit Sarkar (Macmillan) pp 418-423 The Japanese attempted to destroy the main British and Indian forces at Imphal, resulting in some of the most ferocious fighting of the war. While the encircled allied troops were reinforced and resupplied by transport aircraft until fresh troops broke the siege, the Japanese, in part due to torrential rains, ran out of supplies and starved. The surviving forces eventually retreated losing 85,000 men, one of the largest Japanese defeats of the war.
During the monsoon from August to November 1944, the Japanese were pursued to the Chindwin River in Burma. With the onset of the dry season in early 1945, while the American and Chinese forces finally completed the Ledo Road, although too late to have any decisive effect, the British Fourteenth Army, consisting of Indian, British, and African units, launched an offensive into Central Burma. The Japanese forces were heavily defeated, and the Allies pursued them southward, taking Rangoon on May 2 (see Operation Dracula).
===The Western Front (June 1944 – January 1945)===
By the Spring of 1944, the Allied preparations for the invasion of France were complete. They had assembled around 120 Divisions with over 2 million men of which 1.3 million were Americans, 600,000 were British and the rest were Canadians, Free French and Polish units. The invasion was set for June 5th but bad weather postponed the invasion to June 6, 1944.Overy, Richard Almost 85-90% of all German troops were deployed on the Eastern Front and only 400,000 Germans in two armies, the German Seventh Army and the newly created Fifth Panzer Army was all that Germany could spare to defend against the allied invasion. The Germans had also constructed an elaborate series of fortifications along the coast called the Atlantic Wall to deter the invasion but in many places the Wall was incomplete. The Allied forces under supreme command of Dwight D. Eisenhower had launched an elaborate deception campaign to convince the Germans that the landings would occur in the Calais area which caused the Germans to deploy large parts of their forces in that sector. Only 50,000 Germans were deployed in the Normandy sector on the day of the invasion. 
 
The invasion began with 17,000 air borne troops being dropped in Normandy to serve as a screening force to prevent the Germans from attacking the beaches. By early morning, a massive Naval flotilla bombarded German defenses on the beaches but due to rough seas many ships were off target. The Americans in particular suffered heavy losses on Omaha beach due to the German fortifications being left intact. However by the end of the first day, most of the Allied objectives were accomplished even though the British objective of capturing Caen proved too optimistic. The Germans launched no significant counterattack on the beaches as Hitler believed the landings to be a decoy. Only three days later the German High command realized that Normandy was the actual invasion, but by then the Allies had already consolidated their beachheads.
The bocage terrain of Normandy where the Americans had landed made it ideal ground for defensive warfare. Nevertheless, the Americans made steady progress and captured the deep-water port of Cherbourg on June 26, one of the primary objectives of the invasion. However, the Germans had mined the harbor and destroyed most of the port facilities before surrendering, and it would be another month before the port could be brought back into limited use. The British launched another attack on June 13 to capture Caen but were held back as the Germans had moved in large number of troops to hold the city. The city was to remain in German hands for another 6 weeks.
Allied firepower, improved tactics, and numerical superiority eventually resulted in a breakout of American mechanized forces at the western end of the Normandy pocket in Operation Cobra on July 23. When Hitler learned of the American breakout, he ordered his forces in Normandy to launch an immediate counter-offensive. However the German forces moving in open countryside were now easily targeted by Allied aircraft, as they had initially escaped Allied air attacks due to their well camouflaged defensive positions.
The Americans placed strong formations on their flanks which blunted the attack and then began to encircle the 7th Army and large parts of the 5th Panzer Army in the Falaise Pocket. Some 50,000 Germans were captured, but 100,000 managed to escape the pocket. Worse still, the British and Canadians who had been bogged down in their sector now began to break through the German lines. Any hope the Germans had of containing the Allied thrust into France by forming new defensive lines was now gone. The Allies raced across France, advancing as much as 600 miles in two weeksPatton's Third Army advanced 600 miles. The German forces retreated into Northern France, Holland and Belgium. By August 1944, Allied forces stationed in Italy invaded the French Riviera on August 15 and linked up with forces from Normandy. The clandestine French Resistance in Paris rose against the Germans on August 19, and a French armored division under General Philippe Leclerc, pressing forward from Normandy, received the surrender of the German forces there and liberated the city on August 25.
The Germans launched the V-1 flying bomb, the world's first cruise missile, to attack targets in southern England and Belgium. Later, they would employ the V-2 rocket, a liquid-fuelled guided ballistic missile. Neither of these weapons was very accurate and they could only target large areas like cities. They had little military effect but were rather intended to demoralize Allied civilians.
Logistical problems plagued the Allies' advance east as the supply lines still ran back to the beaches of Normandy. Allied paratroopers and armor attempted a war-winning advance through the Netherlands and across the Rhine River with Operation Market Garden in September, but they were repulsed. A decisive victory by the Canadian First Army in the Battle of the Scheldt secured the entrance to the port of Antwerp, which freed it to receive supplies by late November 1944. Meanwhile, the Americans launched an attack through the Hurtgen Forest in September; the Germans, despite having smaller numbers, were able to use the difficult terrain and good defensive positions to hold back the Americans for over 5 months. In October, the Americans captured Aachen, the first major German city to be occupied.
Hitler had been planning to launch a major counteroffensive against the Allies since mid-September. The objective of the attack was to capture Antwerp. Not only would the capture or destruction of Antwerp prevent supplies reaching the allied armies, it would also split allied forces in two, demoralizing the alliance and forcing its leaders to negotiate. For the attack, Hitler concentrated the best of his remaining forces, launching the attack through the Ardennes in southern Belgium, a hilly and in places a heavily wooded region, and the site of his victory in 1940. Dense cloud cover denied the Americans the use of their reconnaissance and ground attack aircraft.
Parts of the attack managed to break through the thinly-held American lines, and dash headlong for the Meuse. However the northern section of the line held, constricting the advance to a narrow corridor. The German advance was delayed at St. Vith, which American forces defended for several days. At the vital road junction of Bastogne, the American 101st Airborne Division held out for the duration of the battle. Patton's 3rd Army to the South made a rapid 90 degree turn and rammed into the German southern flank, relieving Bastogne. 
The weather by this time had cleared unleashing allied air power as the German attack ground to a halt at Dinant. In an attempt to keep the offensive going, the Germans launched a massive air raid on Allied airfields in the Low Countries on January 1, 1945. The Germans destroyed 465 aircraft but lost 277 of their own planes. While the allies recovered their losses in just days, the Luftwaffe was no longer capable of launching major air attack again.A World At Arms, p 769, Gerhard Weinberg 
Allied forces from the north and south met up at Houffalize and by the end of January they had pushed the Germans back to their start positions. Many German units were caught in the pocket created by the Bulge and forced to surrender or retreat without their heavy equipment. Months of the Reich's war production had been expended whereas German forces on the Eastern front were virtually starved of resources at the very moment the Red Army was preparing for its massive offensive against Germany.
===The Eastern Front (January 1945 – April 1945)===
With the Balkans and most of Hungary cleared of German troops by late December 1944, the Soviets began a massive re-deployment of their forces to Poland for their upcoming Winter offensive. Soviet preparations were still on-going when Churchill asked Stalin to launch his offensive as soon as possible to ease German pressure in the West. Stalin agreed and the offensive was set for January 12, 1945. Konev’s armies attacked the Germans in southern Poland and expanded out from their Vistula River bridgehead near Sandomierz. On January 14, Rokossovskiy’s armies attacked from the Narew River north of Warsaw. Zhukov's armies in the centre attacked from their bridgeheads near Warsaw. The combined Soviet offensive broke the defences covering East Prussia, leaving the German front in chaos.
Zhukov took Warsaw by January 17 and by January 19, his tanks took Łódź. That same day, Konev's forces reached the German pre-war border. At the end of the first week of the offensive, the Soviets had penetrated 160 kilometers (100 mi) deep on a front that was 650 kilometers (400 mi) wide. The Soviet onslaught finally halted on the Oder River at the end of January, only 60 kilometers (40 mi) from Berlin.
The Soviets had hoped to capture Berlin by mid-February but that proved hopelessly optimistic. German resistance which had all but collapsed during the initial phase of the attack had stiffened immeasurably. The Russian supply lines were over-extended and discipline among Soviet troops as they were unleashed on German territory all but collapsed. The spring thaw, the lack of air support, and fear of encirclement through flank attacks from East Prussia, Pommern and Silesia led to a general halt in the Soviet offensive. The newly created Army Group Vistula, under the command of Heinrich Himmler, attempted a counter-attack on the exposed flank of the Soviet Army but failed by February 24. This made it clear to Zhukov that the flank had to be secure before any attack on Berlin could be mounted. The Soviets then re-organized their forces and then struck north and cleared Pomerania and then attacked the south and cleared Silesia of German troops. In the south, three German attempts to relieve the encircled Budapest garrison failed, and the city fell to the Soviets on February 13. Again the Germans counter-attacked; Hitler insisting on the impossible task of regaining the Danube River. By March 16, the attack had failed, and the Red Army counter-attacked the same day. On March 30, they entered Austria and captured Vienna on April 13. 
Hitler had believed that the main Soviet target for their upcoming offensive would be in the south near Prague and not Berlin and had send the last remaining German reserves to defend that sector. The Red Army's main goal was in fact Berlin and by April 16 it was ready to begin its final assault on Berlin. Zhukov's forces struck from the center and crossed the Oder river but got bogged down under stiff German resistance around Seelow Heights. After three days of very heavy fighting and 33,000 Russian soldiers dead,http://www.gedenkstaette-seelower-hoehen.de/ the last defenses of Berlin were breached. Konev crossed the Oder river from the South and was within striking distance of Berlin but Stalin ordered Konev to guard the flanks of Zhukov's forces and not attack Berlin, as Stalin had promised the capture of Berlin to Zhukov. Rokossovskiy’s forces crossed the Oder from the North and linked up with British Field Marshal Bernard Montgomery's forces in northern Germany while the forces of Zhukov and Konev captured Berlin.
By April 24, the Soviet army groups had encircled the German Ninth Army and part of the 4th Panzer Army. These were main forces that were supposed to defend Berlin but Hitler had issued orders for these forces to hold their ground and not retreat. Thus the main German forces which were supposed to defend Berlin were trapped southeast of the city. Berlin was encircled around the same time and as a final resistance effort, Hitler called for civilians, including teenagers and the elderly, to fight in the Volkssturm militia against the oncoming Red Army. Those marginal forces were augmented by the battered German remnants who had fought the Soviets in Seelow Heights. Hitler ordered the encircled Ninth Army to break out and link up with the Twelfth Army of General Walther Wenck and relieve Berlin. An impossible task, the surviving units of the Ninth Army were instead driven into the forests around Berlin near the village of Halbe where they were involved in particularly fierce fighting trying to break through the Soviet lines and reach the Twelfth Army. A minority managed to join with the Twelfth Army and fight their way west to surrender to the Americans. Meanwhile the fierce urban fighting continued in Berlin. The Germans had stockpiled a very large quantity of panzerfausts and took a very heavy toll on Soviet tanks in the rubble filled streets of Berlin. However, the Soviets employed the lessons they learned during the urban fighting of Stalingrad and were slowly advancing to the center of the city. German forces in the city resisted tenaciously, in particular the SS Nordland which was made of foreign SS volunteers, because they were ideologically motivated and they believed that they would not live if captured. The fighting was house-to-house and hand-to-hand. The Soviets sustained 360,000 casualties; the Germans sustained 450,000 including civilians and above that 170,000 captured. Hitler and his staff moved into the Führerbunker, a concrete bunker beneath the Chancellery, where on April 30 1945, he committed suicide, along with his bride, Eva Braun.
===War ends in Europe===
Roosevelt, Churchill, and Stalin made arrangements for post-war Europe at the Yalta Conference in February 1945. Their meeting resulted in many important resolutions such as the formation of the United Nations, democratic elections in Poland, borders of Poland moved westwards at the expense of Germany, Soviet nationals were to be repatriated and it was agreed that Soviet Union would attack Japan within three months of Germany's surrender.
The Allies resumed their advance into Germany in late January. The final obstacle to the Allies was the river Rhine, which was crossed in late March 1945, aided by the fortuitous capture of the Ludendorff Bridge at Remagen. Once the Allies had crossed the Rhine, the British fanned out northeast towards Hamburg, crossing the river Elbe and moving on towards Denmark and the Baltic Sea. 
 
The U.S. 9th Army went south as the northern pincer of the Ruhr encirclement, and the U.S. 1st Army went north as the southern pincer of the Ruhr encirclement. These armies were commanded by General Omar Bradley who had over 1,300,000 men under his control. On April 4, the encirclement was completed, and the German Army Group B which included the 5th Panzer Army, 7th Army and the 15th Army commanded by Field Marshal Walther Model was trapped in the Ruhr Pocket. Some 300,000 German soldiers became prisoners of war. The 1st and 9th U.S. armies then turned east. They halted their advance at the Elbe river where they met up with Soviet troops in mid-April.
Allied advances in the winter of 1944–45 up the Italian peninsula had been slow because of the mountainous terrain and troop re-deployments to France. But by April 9, the British/American 15th Army Group broke through the Gothic Line and attacked the Po Valley, gradually enclosing the main German forces. Milan was taken by the end of April. The U.S. 5th Army continued to move west and linked up with French units while the British entered Trieste and met up with the Yugoslav partisans. A few days before the surrender of German troops in Italy, Italian partisans captured Mussolini trying to make his escape to Switzerland. He was executed, along with his mistress, Clara Petacci. Their bodies were taken to Milan and hung upside down on public display.
After Hitler's death, Grand Admiral Karl Dönitz became leader of the German government but the German war effort quickly disintegrated. German forces in Berlin surrendered the city to Soviet troops on May 2, 1945. The German forces in Italy surrendered on May 2, 1945, at General Alexander's headquarters, and German forces in northern Germany, Denmark, and the Netherlands surrendered on May 4. The German High Command under Generaloberst Alfred Jodl surrendered unconditionally all remaining German forces on May 7 in Rheims, France. The western Allies celebrated "V-E Day" on May 8. The Soviet Union celebrated "Victory Day" on May 9. Some remnants of German Army Group Center continued resistance until May 11 or May 12 (see Prague Offensive). 
===War ends in Asia===
 
The last Allied conference of World War II was held at the suburb of Potsdam, outside Berlin, from July 17 to August 2. During the Potsdam Conference, agreements were reached among the Allies on policies for occupied Germany. An ultimatum was issued calling for the unconditional surrender of Japan.
U.S. president Harry Truman decided to use the new atomic weapon to bring the war to a swifter end. The battle for Okinawa had shown that an invasion of the Japanese mainland (planned for November) would result in large numbers of American casualties. The official estimate given to the Secretary of War was 1.4 to four million Allied casualties, though some historians dispute whether this would have been the case. Invasion would have meant the death of millions of Japanese soldiers and civilians, who were being trained as militia. 
On August 6, 1945, a B-29 Superfortress, the Enola Gay, dropped a nuclear weapon dubbed Little Boy on Hiroshima, destroying the city. On August 9, a B-29 named Bockscar dropped the second atomic bomb, dubbed Fat Man, on the port city of Nagasaki.
On August 8, two days after the atomic bomb was dropped on Hiroshima, the Soviet Union, having renounced its nonaggression pact with Japan in April, attacked the Japanese in Manchuria, fulfilling its Yalta pledge to attack the Japanese within three months after the end of the war in Europe. The attack was made by three Soviet army groups. In less than two weeks, the Japanese army in Manchuria, consisting of over a million men, had been destroyed by the Soviets. The Red Army moved into North Korea on August 18. Korea was subsequently divided at the 38th parallel into Soviet and U.S. zones.
The American use of atomic weapons against Japan and the Soviet invasion of Manchukuo prompted Hirohito to bypass the existing government and intervene to end the war. In his radio address to the nation, the Emperor did not mention the entry of the Soviet Union into the war, but in his "Rescript to the soldiers and sailors" of August 17, ordering them to cease fire and lay down arms, he stressed the relationship between Soviet entrance into the war and his decision to surrender, omitting any mention of the atomic bombs. 
The Japanese surrendered on August 14, 1945, or V-J day, signing the Japanese Instrument of Surrender on September 2. The Japanese troops in China formally surrendered to the Chinese on September 9, 1945.
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==Casualties, civilian impact, and atrocities==
Main articles : World War II casualties, The Holocaust, Concentration camp, Gulag, Japanese war crimes, Comfort women, Nanking massacre, Japanese American internment and War crimes during World War II
Some 63 million people, or 3% of the world population, died in the war (though estimates vary): about 24 million soldiers and 38 million civilians. This total includes the estimated 9 million lives lost in the Holocaust. Of the total deaths in World War II, approximately 80% were on the Allied side and 20% on the Axis side.World War II casualties
Allied forces suffered approximately 17 million military deaths, of which about 11 million were Soviet and 3 million Chinese. Axis forces suffered about 8 million, of which more than 5 million were German. In total, of the military deaths in World War II, approximately 44% were Soviet soldiers, 22% were German, 12% were Chinese, 8% were Japanese, 9% were soldiers of other Allied forces, and 5% were other Axis country soldiers. Some modern estimates double the number of Chinese casualties originally stated. Of the civilian deaths, approximately 90% were Allied (nearly a third of all civilians killed were Soviet citizens, and more than 15% of all civilians killed in the war died in German extermination camps) and 10% were Axis.
Many civilians died as a result of disease, starvation, massacres, genocide—in particular, the Holocaust—and aerial bombing. One estimate is that 12 million civilians died in Holocaust camps, 1.5 million by bombs, 7 million in Europe from other causes, and 7.5 million in China from other causes.J. M. Winter, "Demography of the War", in Dear and Foot, ed., Oxford Companion to World War, p 290. Allied civilian deaths totaled roughly 38 million, including 11.7 million in the Soviet Union, 7 million in China and 5.2 million from Poland. There were around 3 million civilian deaths on the Axis side, including 2 million in Germany and 0.6 million in Japan. The Holocaust refers to the organized state-sponsored murder of 6 million Jews, 1.8-1.9 million non-Jewish Poles, 200,000–800,000 Roma people, 200,000–300,000 people with disabilities, and other groups carried out by the Nazis during the war. The Soviet Union suffered by far the largest death toll of any nation in the war, over 23 million.
In addition to the Nazi concentration camps, the Soviet Gulag, or labor camps, led to the death of citizens of occupied countries such as Poland, Lithuania, Latvia, and Estonia, as well as German prisoners of war (POW) and even Soviet citizens themselves who had been supporters of the Nazis or were thought to be the ones. Japanese POW camps also had high death rates; many were used as labour camps, and starvation conditions among the mainly U.S., British, Australian and other Commonwealth prisoners were little better than many German concentration camps. Sixty percent (1,238,000 ref. Krivosheev) of Soviet POWs died during the war. Vadim Erlikman puts it at 2.6 million Soviet POWs that died in German Captivity.Erlikman, Vadim Richard Overy gives the number of 5.7 million Soviet POW and out of those 57% died or were killed.Richard Overy The Dictators Hitler's Germany, Stalin's Russia p.568–569
On February 19, 1942, Roosevelt signed Executive Order 9066, leading to the internment of thousands of Japanese, Italians, German Americans, and some emigrants from Hawaii who fled after the bombing of Pearl Harbor for the duration of the war. 150,000 Japanese-Americans were interned by the U.S. and Canadian governments, as well as nearly 11,000 German and Italian residents of the U.S.
Despite the international treaties and a resolution adopted by the League of Nations on 14 May 1938 condemning the use of toxic gas by Japan, the Imperial Japanese Army frequently used chemical weapons. Because of fears of retaliation, however, those weapons were never used against Westerners but only against other Asians judged "inferior" by the imperial propaganda. According to historians Yoshiaki Yoshimi and Seiya Matsuno, the authorization for the use of chemical weapons was given by specific orders (rinsanmei) issued by Hirohito himself. For example, the Emperor authorized the use of toxic gas on 375 separate occasions during the invasion of Wuhan, from August to October 1938.
The bacteriological weapons were experimented on human beings by many units incorporated in the Japanese army, such as the infamous Unit 731, integrated by Imperial decree in the Kwantung army in 1936. Those weapons were mainly used in China and, according to some Japanese veterans, against Mongolians and Russian soldiers in 1939 during the Nomonhan incident.Hal Gold, Unit 731 testimony, p.64–65, 1996. 
According to a joint study of historians featuring Zhifen Ju, Mark Peattie, Toru Kubo, and Mitsuyochi Himeta, more than 10 million Chinese were mobilized by the Japanese army and enslaved by the Kôa-in for slave labor in Manchukuo and north China.Zhifen Ju, "Japan's atrocities of conscripting and abusing north China draftees after the outbreak of the Pacific war", 2002 According to Mitsuyoshi Himeta, at least 2.7 million died during the Sankō Sakusen operation implemented in Heipei and Shantung by General Yasuji Okamura.
From 1945 to 1951, German and Japanese officials and personnel were prosecuted for war crimes. Top German officials were tried at the Nuremberg Trials, and many Japanese officials at the Tokyo War Crime Trial and other war crimes trials in the Asia-Pacific region.
==Resistance and collaboration==
Resistance during World War II occurred in every occupied country by a variety of means, ranging from non-cooperation, disinformation, and propaganda to outright warfare.
Among the most notable resistance movements were the Polish Home Army, the French Maquis, the Yugoslav Partisans, the Greek resistance force, and the Italian Resistance in the German-occupied Northern Italy after 1943. Germany itself also had an anti-Nazi movement. The Communist resistance was among the fiercest, since they were already organised and militant even before the war and they were ideologically opposed to the Nazis. 
Before D-Day, there were some operations performed by the French Resistance to help with the forthcoming invasion. Communications lines were cut; trains were derailed; roads, water towers, and ammunition depots were destroyed; and some German garrisons were attacked.
There were also resistance movements fighting against the Allied invaders. The German resistance petered out within a few years, while in the Baltic states resistance operations against the occupation continued into the 1960s.
==Home fronts==
"Home front" is the name given to the activities of the civilians of the nations at war. All the main countries reorganized their homefronts to produce munitions and soldiers, with 40–60% of GDP being devoted to the war effort. Women were drafted in the Soviet Union and Britain. Shortages were everywhere, and severe food shortages caused malnutrition and even starvation, such as in the Netherlands and in Leningrad. New workers were recruited, especially housewives, the unemployed, students, and retired people. Skilled jobs were re-engineered and simplified ("de-skilling") so that unskilled workers could handle them. Every major nation imposed censorship on the media as well as a propaganda program designed to boost the war effort and stifle negative rumors. Every major country imposed a system of rationing and price controls. Black markets flourished in areas controlled by Germany. Germany brought in millions of prisoners of war, slave laborers, and forced workers to staff its munitions factories. Many were killed in the bombing raids, the rest became refugees as the war ended.
==Technology== 
Weapons and technology improved rapidly during World War II and some of these played a crucial role in determining the outcome of the war. Many major technologies were used for the first time, including nuclear weapons, radar, proximity fuses, jet engines, ballistic missiles, and data-processing analog devices (primitive computers). Every year, the piston engines were improved. Enormous advances were made in aircraft, submarine, and tank designs, such that models coming into use at the beginning of the war were long obsolete by its end. One entirely new kind of ship was the amphibious landing craft.
Industrial production played a role in the Allied victory. The Allies more effectively mobilized their economies and drew from a larger economic base. The peak year of munitions production was 1944, with the Allies out-producing the Axis by a ratio of 3 to 1. (Germany produced 19% and Japan 7% of the world's munitions; the U.S. produced 47%, Britain and Canada 14%, and the Soviets 11%).
Raymond W. Goldsmith, "The Power of Victory: Munitions Output in World War II" Military Affairs, Vol. 10, No. 1. (Spring, 1946), pp. 69–80; online at JSTOR
The Allies used low-cost mass production techniques, using standardized models. Japan and Germany continued to rely on expensive hand-crafted methods. Japan thus produced hundreds of airplane designs and did not reach mass-production efficiency; the new models were only slightly better than the original 1940 planes, while the Allies rapidly advanced in technology. Richard Overy. The Air War, 1939–1945 (2005) Germany thus spent heavily on high-tech weaponry, including the V-1 flying bomb and V-2 rocket, advanced submarines, jet engines, and heavy tanks that proved strategically of minor value. The combination of better logistics and mass production proved crucial in the victory. "The Allies did not depend on simple numbers for victory but on the quality of their technology and the fighting effectiveness of their forces... In both Germany and Japan less emphasis was placed upon the non-combat areas of war: procurement, logistics, military services," concludes historian Richard Overy.Overy (1993) p 318–9
Delivery of weapons to the battlefront was a matter of logistics. The Allies again did a much better job in moving munitions from factories to the front lines. A large fraction of the German tanks after June 1944 never reached the battlefield, and those that did often ran short of fuel. Japan in particular was notably inefficient in its logistics system. Mark Parillo, "The Pacific War" in Richard Jensen et al, eds. Trans-Pacific Relations: America, Europe, and Asia in the Twentieth Century (2003), pp. 93–104.
Many new medical and surgical techniques were employed as well as new drugs like sulfa and penicillin, not to mention serious advances in biological warfare and nerve gases. The Japanese control of the quinine supply forced the Australians to invent new anti-malarial drugs. The saline bath was invented to treat burns. More prompt application of sulfa drugs saved countless lives. New local anesthetics were introduced making possible surgery close to the front lines. The Americans discovered that only 20% of wounds were caused by machine-gun or rifle bullets (compared to 35% in World War I). Most came from high explosive shells and fragments, which besides the direct wound caused shock from their blast effects. Most deaths came from shock and blood loss, which were countered by a major innovation, blood transfusions. Harold C. Leuth, "Military Medicine" in Walter Yust, ed. 10 Eventful Years (1947) 3:163–67; Mark Harrison, Medicine and Victory: British Military Medicine in the Second World War (2004)
Cryptography played an important part in the war, as the United States had broken the Japanese naval codes and knew the Japanese plan of attack at Midway. British and Polish codebreakers deciphered several German codes, giving the Allies an advantage in the European theater as well.
The massive research and development demands of the war accelerated the growth of the scientific communities in Allied states, while German and Japanese laboratories were disbanded; many German engineers and scientists continued their weapons research after the war in the United States, the Soviet Union and other countries.
Read below for more information on technology in the war.
==Military Intelligence==
Both Allied and German intelligence failed to effectively conduct human intelligence gathering, except for prisoner interrogation. The reason is that it is very difficult to train agents to be fluent in the language and culture of the enemy. For example, all German agents parachuted onto British soil were quickly caught by the British authorities, and most were turned. Also, German intelligence turned many English agents on the European continent; virtually no English agent operated in German territory.
Technical intelligence gathering was much more effective, mainly on the Allied side. The most important cryptologic systems of both Germany and Japan, Enigma and JN-25 respectively, were analysed and were broken by Polish, British and American cryptologists. This gave the Allied war effort a distinctive edge: Allied commanders knew what their Axis opponents were planning. The defeat of the German Afrika Korps and the elimination of a large number of German submarines is attributed to the Allied success in reading communications deemed "secure" by the German High Command. 
The naval intelligence situation in the Pacific was very similar: American naval intelligence often knew about Japanese plans well in advance and could dispatch their warships accordingly. The commander of the US pacific fleet (Admiral Nimitz)later stated that communications intelligence was as valuable "as an additional fleet" in the Pacific theater.
The success of communications intelligence during World War II seems to be a major reason for the UKUSA group of countries to fund large SIGINT organizations like NSA and GCHQ, which are in operation up to the present day.
However, it is notable that Germany had some success in breaking the American M-209 cryptomachine, but this device was mainly used for tactical communications. Unfortunately, very few facts about German SIGINT during WW2 is known. See this German story.
==Aftermath==
The war concluded with the surrender and occupation of Germany and Japan. It left behind millions of displaced persons and prisoners of war, and resulted in many new international boundaries. The economies of Europe, China and Japan were largely destroyed as a result of the war. In 1947, U.S. Secretary of State George Marshall devised the "European Recovery Program", better known as the Marshall Plan. Effective from 1948 to 1952, it allocated 13 billion dollars for the reconstruction of Western Europe. To prevent (or at least minimize) future conflicts, the allied nations, led by the United States, formed the United Nations in San Francisco in 1945. One of the first actions of the United Nations was the creation of the State of Israel, partly in response to the Holocaust.
===Aftermath of World War II in Europe===
The end of the war hastened the independence of many British crown colonies (such as India) and Dutch territories (such as Indonesia) and the formation of new nations and alliances throughout Asia and Africa. The Philippines were granted their independence in 1946 as previously promised by the United States. Poland's boundaries were re-drawn to include portions of pre-war Germany, including East Prussia and Upper Silesia, while ceding most of the areas taken by the Soviet Union in the Molotov-Ribbentrop partition of 1939, effectively moving Poland to the west. Germany was split into four zones of occupation, and the three zones under the Western Allies was reconstituted as a constitutional democracy. The Soviet Union's influence increased as they established hegemony over most of eastern Europe, and incorporated parts of Finland and Poland into their new boundaries. Europe was informally split into Western and Soviet spheres of influence, which heightened existing tensions between the two camps and helped establish the Cold War.
Germany was partitioned into four zones of occupation, coordinated by the Allied Control Council. The American, British, and French zones joined in 1949 as the Federal Republic of Germany, and the Soviet zone became the German Democratic Republic. In Germany, economic suppression and denazification took place. Millions of Germans and Poles were expelled from their homelands as a result of the territorial annexations in Eastern Europe agreed upon at the Yalta and Potsdam conferences. In the West, Alsace-Lorraine was returned to France, and the Saar area was separated from Germany. Austria was divided into four zones of occupation, which were united in 1955 to become the Republic of Austria. The Soviet Union occupied much of Central and Eastern Europe and the Balkans. In all the USSR-occupied countries, with the exception of Austria, the Soviet Union helped Communist regimes to power. It also annexed the Baltic countries Estonia, Latvia, and Lithuania.
===Aftermath of World War II in Asia===
In Asia, Japan was occupied by the U.S, aided by Commonwealth troops, until the peace treaty took effect in 1952. The Japanese Empire's government was dismantled under General Douglas MacArthur and replaced by a constitutional monarchy with the emperor as a figurehead. The defeat of Japan also led to the establishment of the Far Eastern commission which set out policies for Japan to fulfill under the terms of surrender. In accordance with the Yalta Conference agreements, the Soviet Union occupied and subsequently annexed Sakhalin and the Kuril islands. Japanese occupation of Korea also ended, but the peninsula was divided between the U.S. and the Soviet Union, along 38th parallel. The U.S.-backed South Korea would fight the communist North Korea in the Korean War, with Korea remain divided.
World War II was a pivotal point in China's history. Before the war against Japan, China had suffered nearly a century of humiliation at the hands of various imperialist powers and was relegated to a semi-colonial status. However, the war greatly enhanced China's international status. Not only was the central government under Chiang Kai-shek able to abrogate most of the unequal treaties China had signed in the past century, the Republic of China also became a founding member of the United Nations and a permanent member in the Security Council. China also reclaimed Manchuria and Taiwan. Nevertheless, eight years of war greatly taxed the central government, and many of its nation-building measures adopted since it came to power in 1928 were disrupted by the war. Communist activities also expanded greatly in occupied areas, making post-war administration of these areas difficult. Vast war damages and hyperinflation thereafter demoralized the populace, along with the continuation of the Chinese Civil War between the Kuomintang and the Communists. Partly because of the severe blow his army and government had suffered during the war against Japan, the Kuomintang, along with state apparatus of the Republic of China, retreated to Taiwan in 1949 and in its place the Chinese communists established the People's Republic of China on the mainland.
==Media==
The term most used in the United Kingdom and Canada is "Second World War", while American publishers use the term "World War II". Thus the Oxford University Press uses The Oxford Companion to the Second World War in the United Kingdom, and The Oxford Companion to World War II for the identical 1995 book in the United States.
The OED reports the first use of "Second World War" was by novelist H.G. Wells in 1930, although it may well have been used earlier. Library catalogs show the first use in 1934: Why war? A handbook for those who will take part in the second world war by Ellen Wilkinson & Edward Conze, (London, 1934), and Johannes Steel, The second world war, (New York, 1934). The term was immediately used when war was declared; for example, the September 3, 1939, issue of the Canadian newspaper, The Calgary Herald. Prior the United States' entry into the War, many Americans referred to it as the "European War".
World War II has been portrayed in numerous media in many languages. 
Films include Twelve O'Clock High (1949), The Bridge on the River Kwai (1957), The Dirty Dozen (1967), A Bridge too Far (1977), Das Boot (1981), and Saving Private Ryan (1998). The war figures prominently in thousands of written works, including Joseph Heller's Catch-22, Akiyuki Nosaka's Grave of the Fireflies, Anne Frank's The Diary of a Young Girl and Kurt Vonnegut's Slaughterhouse-Five. Games set within World War II include the board game Axis and Allies and 
video games 1942 (1984), Wolfenstein 3D (1992), and Call of Duty (2003). The war has been portrayed in many television media, such as Hogan's Heroes (1965–1971) and the miniseries Band of Brothers (2001).
==Notes==
==Bibliography==
* Bauer, E. Lt-Colonel The History of World War II, Orbis (2000) General Editor: Brigadier Peter Young; Consultants: Brigadier General James L. Collins Jr., Correli Barnet. (1,024 pages) ISBN 1-85605-552-3
* Churchill, Winston S. The Second World War. (6 volumes). (1948-1953). ISBN 978-0395416853 
* I.C.B. Dear and M.R.D. Foot, eds. The Oxford Companion to World War II (1995), 1300 page encyclopedia covering all topics
* Ellis, John. Brute Force: Allied Strategy and Tactics in the Second World War (1999) 
*Gilbert, Martin Second World War (1995)
* Mark Harrison. "Resource Mobilization for World War II: The U.S.A., UK, U.S.S.R., and Germany, 1938–1945" in The Economic History Review, Vol. 41, No. 2. (May, 1988), pp. 171–192. in JSTOR
*Keegan, John. The Second World War (1989)
* Jon Latimer, Burma: The Forgotten War, London: John Murray, (2004)
* Liddell Hart, Sir Basil History of the Second World War (1970)
* Murray, Williamson and Millett, Allan R. A War to Be Won: Fighting the Second World War (2000)
* Overy, Richard. Why the Allies Won (1995)
* Shirer, William L. The Rise and Fall of the Third Reich, Simon & Schuster. (1959). ISBN 0-671-62420-2. 
*Smith, J. Douglas and Richard Jensen (2003). World War II on the Web: A Guide to the Very Best Sites. ISBN 0-8420-5020-5.
*Weinberg, Gerhard L.A World at Arms: A Global History of World War II (2005) ISBN 0-521-44317-2
*
==External links==
===Directories===
*Referencio – "World War II" — Wiki directory
*Open Directory Project – "World War II" — volunteer directory
*Yahoo – "World War II
===General===
*Austria Chronology World War II World History Database
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*Original Document: D-Day Statement from Dwight D. Eisenhower
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*Deutsche Welle special section on World War II created by one of Germany's public broadcasters on World War II and the world 60 years after.
*Directory of Online World War II Indexes & Records
*Halford Mackinder's Necessary War An essay describing the geopolitical aspects of World War II
*World War 2 Vault
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*Canada and WWII
*Original Document Surrender of Japan
*World War II Military Situation Maps. Library of Congress
*Officially Declassified U.S. Government Documents about World War II 
*End of World War II in Germany
*World War 2 Pictures In Colour
*Haagse Bunker Ploeg : Photo site about the atlantikwall in the Netherlands
*WWW-VL: History: WWII
*World War II Zone Photo and Multi-media gallery
*Daily German action reports
*Timeline of events in World War 2 on WikiTimeScale.org
*Maps from the Pacific and Italian theaters
*Original Document Surrender of Germany
===Media===
*U.S. National Archives Photos
*Multimedia map — Presentation that covers the war from the invasion of Russia to the fall of Berlin
*Thousands of World War II Photographs & Movies
*Virtual Museum of World War II — pictures & info
*3-D Stereo Photograph of Iwo Jima Flag-raising — From The Tampa Tribune and TBO.com
*World War II Poster Collection hosted by the Universtity of North Texas Libraries' *Digital Collections
*The Defeat of France Includes the famous Weeping Frenchman photograph.
*(Italian) ANPI Archives Photos
===Stories===
*Voices in the Dark — Descriptions of life in Nazi-occupied Paris
*WW2 People's War — A project by the BBC to gather the stories of ordinary people from World War II
*Memories of Leutnant d.R. Wilhelm Radkovsky 1940–1945 Experiences as a German soldier on the Eastern and Western Front
*The Warsaw Uprising of 1944 — "a heroic and tragic 63-day struggle to liberate World War 2 Warsaw from Nazi/German occupation."
*(Italian) La Città Invisibile Collection of signs, stories and memories during the Gothic Line age.
===Documentaries===
*The World at War (1974) is a 26-part Thames Television series that covers most aspects of World War II from many points of view. It includes interviews with many key figures (Karl Dönitz, Albert Speer, Anthony Eden etc.) (Imdb link)
*The Second World War in Colour (1999) is a three episode documentary showing unique footage in color (Imdb link)
*Red White Black & Blue — Feature documentary about The Battle of Attu in the Aleutians during World War II
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