Diplomatic history of World War II The Diplomatic history of World War II includes the major foreign policies and interactions inside the opposing coalitions , the Allies and the Axis powers . The military history of the war is covered at World War II . Allies . Britain , France ( until 1940 ) , the Soviet Union ( after 1941 ) and the United States were the main Allies . They were joined by numerous smaller countries , such as Canada , as well as governments in exile , such as the Netherlands . Big Three conferences . Britain , the USSR and the US , were in frequent contact through ambassadors , top generals , foreign ministers and special emissaries such as the American Harry Hopkins . There were numerous high - level conferences ; in total Churchill attended 14 meetings , Roosevelt 12 , and Stalin 5 . Most visible were the three summit conferences that brought together the three top leaders . Tehran conference . The first meeting of the Big Three , Stalin , Roosevelt and Churchill , came at the Tehran Conference in Iran in 28 November to 1 December 1943 . It agreed on an invasion of France in 1944 ( the " Second front " ) and dealt with Turkey , Iran , Yugoslavia and the war against Japan as well as the post - war settlement . Yalta conference . The Yalta Conference met in the Crimea ( Russia ) February 4 – 11 , 1945 . It focused on postwar plans for European boundaries . The Soviets already controlled Poland . The new boundaries of Poland were especially important , with Stalin seeking control of western Belorussia and western Ukraine . Poland was to gain parts of Germany . Stalin promised free elections in Poland under the auspices of a government he controlled . At Roosevelt ' s strong urging , Stalin agreed to enter the war against Japan three months after the defeat of Germany . It was agreed the USSR would be a member of the United Nations Security Council , with a veto , and Ukraine and Belorussia would be UN members , but not the other 12 Soviet republics . Germany was to be divided into three zones of occupation , and France was also to get a zone . In a decision that became highly controversial , all civilians would be repatriated . Britain . Britain ' s declaration of war against Germany in September 1939 included the Crown colonies and India , which it directly controlled . The dominions were independent in foreign policy but all of them ( Australia , Canada , New Zealand , and South Africa ) soon declared war on Germany . The fears in London that South Africa would take the advice of Prime Minister J . B . M . Hertzog and remain neutral were relieved when the parliament voted 80 to 67 for war , and Hertzog resigned . After the French defeat in June 1940 , Britain and its empire stood alone in combat against Germany , until June 1941 . The United States gave strong diplomatic , financial and material support , starting in 1940 , especially through Lend Lease , which began in 1941 , In August 1941 , Churchill and Roosevelt met and agreed on the Atlantic Charter , which proclaimed " the rights of all peoples to choose the form of government under which they live " should be respected . This wording was ambiguous and would be interpreted differently by the British , Americans , and nationalist movements . Starting in December 1941 , Japan overran British possessions in Asia , including Hong Kong , Malaya , and especially the key base at Singapore , and marched into Burma , headed toward India . Churchill ' s reaction to the entry of the United States into the war was that Britain was now assured of victory and the future of the empire was safe , but the rapid defeats irreversibly harmed Britain ' s standing and prestige as an imperial power . The realisation that Britain could not defend them pushed Australia and New Zealand into permanent close ties with the United States . Britain - United States . Though most Americans favoured Britain in the war , there was widespread opposition to American military intervention in European affairs . President Roosevelt ' s policy of cash - and - carry still allowed Britain and France to purchase munitions from the United States and carry them home . Churchill , who had long warned against Germany and demanded rearmament , became prime minister after Chamberlain ' s policy of appeasement had totally collapsed and Britain was unable to reverse the German invasion of Norway in April 1940 . After the fall of France Roosevelt gave Britain all aid short of war . The Destroyers for Bases Agreement of September 1940 , gave the United States a ninety - nine - year lease on strategically located bases in the Atlantic in exchange for the Royal Navy receiving fifty old destroyers to use in anti - submarine warfare . Roosevelt also sold ( for cash ) munitions that were carried away in British ships , including over half a million rifles , 85 , 000 machine guns , 25 , 000 automatic rifles , mortars , hundreds of field guns , with supplies of the necessary ammunition . The British needed these munitions to reequip the soldiers who lost all their arms when Dunkirk was evacuated in June 1940 . Beginning in March 1941 , the United States enacted Lend - Lease sending tanks , warplanes , munitions , ammunition , food , and medical supplies . Britain received $ 31 . 4 billion out of a total of $ 50 . 1 billion of supplies sent to the Allies . In sharp contrast to the First World War , these were not loans and no repayment was involved . Arcadia . The Arcadia Conference was held in Washington , from December 22 , 1941 to January 14 , 1942 , bringing together the top British and American military leaders in Washington , December 22 , 1941 , to January 14 , 1942 . Winston Churchill and Franklin Roosevelt and their aides had very candid conversations that led to a series of major decisions that shape the war effort in 1942 – 1943 . The decision was made to invade North Africa in 1942 , to send American bombers to bases in England , and for the British to strengthen their forces in the Pacific . The Conference established the Combined Chiefs of Staff , headquartered in Washington , which approved and finalized all military decisions . It also created a unified American - British - Dutch - Australian Command ( ABDA ) in the Far East ; it fared poorly . Finally the conference drafted the Declaration by the United Nations , which committed the Allies to make no separate peace with the enemy , and to employ full resources until victory . At the Quebec Conference , 1943 held in Canada in August 1943 , Churchill , Roosevelt and the Combined Chiefs plotted strategy against Germany . They began planning the invasion of France , codenamed Overlord using a report by the Combined Chiefs . They also discussed an increase of the bombing offensive against facilities Germany was using in France and the Low Countries . They decided to continue the buildup of American forces in Britain prior to an invasion of France . Churchill kept drawing attention to the advantages of operations in the Mediterranean theatre . They agreed to use more force to force Italy out of the war , and to occupy it along with Corsica . Military cooperation was close and successful . Technical collaboration . Technical collaboration was even closer , as the two nations shared secrets and weapons regarding the proximity fuze and radar , as well as airplane engines , Nazi codes , and the atomic bomb . Millions of American servicemen were based in Britain during the war , which led to a certain amount of friction with British men and intermarriage with British women . This animosity was explored in art and film , most particularly " A Matter of Life and Death " and " A Canterbury Tale " . In 1945 Churchill sent British fleet to help the United States attack and invade Japan . Casablanca conference . From January 14 – 24 , 1943 Roosevelt , Churchill and the Combined Staff met in Casablanca , Morocco . They decided on the major Allied strategy for 1943 in Europe , especially the invasion of Italy and planning for the invasion of France . At Roosevelt ' s suggestion they agreed on a policy of " unconditional surrender . " This policy uplifted Allied morale , but it also made the Nazis resolve to fight to the bitter end . Roosevelt also tried to establish a working relationship between the two main French allies , Henri Giraud , the French high commissioner in North Africa , and General de Gaulle , leader of the Free French . India . Serious tension erupted over American demands that India be given independence , a proposition Churchill vehemently rejected . For years Roosevelt had encouraged Britain ' s disengagement from India . The American position was based on principled opposition to colonialism , practical concern for the outcome of the war , and the expectation of a large American role in a post - colonial era . However in 1942 when the Congress Party launched a Quit India movement , the British authorities immediately arrested tens of thousands of activists , including Jawaharlal Nehru and Mahatma Gandhi , and imprisoned them until 1945 . Meanwhile India became the main American staging base for aid to China . Churchill threatened to resign if Roosevelt pushed too hard regarding independence , so Roosevelt backed down . Britain and France . In spring 1939 both Britain and France formally announced they would defend the integrity of Poland . Hitler did not believe they would fight in such a faraway hopeless cause , and he invaded Poland on September 1 , 1939 . Britain and France declared war on September 3 , 1939 . But there was little they could or did do to help Poland . When Germany began its attack on France in April 1940 , British troops and French troops again fought side by side , but defeat came quickly . The Royal Navy evacuated 198 , 000 British and 140 , 000 French soldiers in the Dunkirk evacuation in late May / early June 1940 . Tens of thousands of tanks , trucks and artillery guns were left behind , as well as all of the radios , machine guns , spare parts and other gear . The new Prime Minister Winston Churchill pledged that Britain would continue to fight for France ' s freedom , even if it must do so alone . Britain and Soviet Union . In October 1944 Churchill and his Foreign Minister Anthony Eden met in Moscow with Stalin and his foreign minister Molotov . They planned who would control what in postwar Eastern Europe . They agreed to give 90 % of the influence in Greece to Britain and 90 % in Romania to Russia . Russia gained an 80 % / 20 % division in Bulgaria and Hungary . There was a 50 / 50 division in Yugoslavia , and no Russian share in Italy . Middle East . Iraq . Iraq was an independent country in 1939 , with a strong British presence , especially in the oil fields . Iraq broke relations with Germany but there was a srong pro - German element . The regime of Regent ' Abd al - Ilah was overthrown in 1941 by the Golden Square pro - Nazi army officers , headed by Rashid Ali . The short living pro - Nazi government was overpowered in May 1941 by British forces in Anglo - Iraqi War and the Regent returned to power . Iraq was later used as a base for allied attacks on Vichy - French held Mandate of Syria and support for the Anglo - Soviet invasion of Iran . Iran ( Persia ) . In 1939 the dictator of Iran was Shah Reza Pahlevi , an army officer who took control in a coup d ' état in 1925 and called himself " shah . " He was a modernizer who had little use for traditional religion , but collaborated with the Germans . Iran proclaimed neutrality when the war began in 1939 . British and Soviet forces occupied Iran in August 1941 , deposed the Shah , and installed his son Mohammad Reza Shah Pahlavi . Iran , with a largely rural population of 13 million , had oil wells and became a major route for shipping military supplies from the U . S . to the Soviet Union . At the Tehran Conference of 1943 , Stalin , Roosevelt and Churchill issued the Tehran Declaration that guaranteed the post - war independence and boundaries of Iran . However , when the war actually ended , Soviet troops stationed in northwestern Iran not only refused to withdraw but backed revolts that established short - lived , pro - Soviet separatist national states in the northern regions of Azerbaijan and Iranian Kurdistan , the Azerbaijan People ' s Government and the Republic of Kurdistan respectively , in late 1945 . Soviet troops did not withdraw from Iran proper until May 1946 after receiving a promise of oil concessions . The Soviet republics in the north were soon overthrown and the oil concessions were revoked . Commonwealth . The British dominions joined in the September 3 declaration of war , except for Canada . In a symbolic statement of autonomous foreign policy , Prime Minister William Lyon Mackenzie King delayed Parliament ' s vote on a declaration of war until September 10 . Britain generally handled the diplomatic relations of the Commonwealth nations . Canada hosted top level conferences between Britain and the U . S . , but did not itself participate in the formal discussions . Australia , however , felt abandoned by London and moved to a close relationship with the U . S . , playing a support role in the American war against Japan . Australian Prime Minister John Curtin stated , " I make it clear that Australia looks to America , free of any pangs as to our traditional links or kinship with the United Kingdom . " United States . US - China . The United States was a strong supporter of China after Japan invaded in 1937 . Even the isolationists who opposed war in Europe supported a hard - line against Japan . The outbreak of the Second Sino - Japanese War in 1937 saw aid flow into the Republic of China , led by Chiang Kai - shek . American public sympathy for the Chinese was aroused by reports from missionaries , novelists such as Pearl Buck , and " Time Magazine " of Japanese brutality in China , including reports surrounding the Nanking Massacre , also known as the ' Rape of Nanking ' . Japanese - American relations were further soured by the USS Panay Incident during the bombing of Nanjing . Roosevelt demanded an apology from the Japanese , which was received , but relations between the two countries continued to deteriorate . By early 1941 the U . S . was preparing to send American planes flown by American pilots under American command , but wearing Chinese uniforms , to fight the Japanese invaders and even to bomb Japanese cities . The " Flying Tigers " under Claire Chennault arrived just as the U . S . entered the war . To augment Chennault ' s 100 P - 40Bs , in May 1941 Washington decided to send 144 Vultee P - 48 ' s , 125 P - 43 ' s and 66 Lockheed and Douglas medium bombers . The goal was to give China by early 1942 , a respectable air force , judged by Far Eastern standards , sufficient to " ( a ) protect strategic points , ( b ) permit local army offensive action , ( c ) permit the bombing of Japanese air bases and supply dumps in China and Indo - China , and the bombing of coastal and river transport , and ( d ) permit occasional incendiary bombing of Japan . " A year before the U . S . officially entered the war ( after Dec . 7 , 1941 ) , Chennault developed an ambitious plan for a sneak attack on Japanese bases . His Flying Tigers would use American bombers and American pilots , all with Chinese markings . The U . S . military was opposed to his scheme , and kept raising obstacles , but it was adopted by top civilian officials including Henry Morgenthau , Jr . ( the Secretary of the Treasury who financed China ) and especially President Roosevelt himself , who made it a high priority to keep China alive . By October , 1941 , bombers and crews were on their way to China . However the American attack never took place . The bombers and crews arrived after Pearl Harbor and were used for the war in Burma , for they lacked the range to reach China . Wartime . After the formal declaration of war in December 1941 , the U . S . stepped up the flow of aid , but it had to be routed through India and over the Himalayan Mountains because Japan blocked the other routes . Chiang ' s beleaguered government was now headquartered in remote Chongqing . Madame Chiang Kaishek , who had been educated in the United States , addressed the US Congress and toured the country to rally support for China . Congress amended the Chinese Exclusion Act and Roosevelt moved to end the unequal treaties . However , the perception that Chiang ' s government , with his poorly equipped and ill - fed troops was unable to effectively fight the Japanese or that he preferred to focus more on defeating the Communists grew . China Hands such as Joseph Stilwell argued that it was in American interest to establish communication with the Communists to prepare for a land - based counteroffensive invasion of Japan . The Dixie Mission , which began in 1943 , was the first official American contact with the Communists . Other Americans , such as Claire Chennault , argued for air power . In 1944 , Generalissimo Chiang acceded to Roosevelt ' s request that an American general take charge of all forces in the area , but demanded that Stilwell be recalled . General Albert Wedemeyer replaced Stilwell , Patrick Hurley became ambassador , and Us - China relations became much smoother . After World War II ended in 1945 , the showdown came between the Nationalists and the Communists in a full - scale civil war . American general George C . Marshall tried to broker a truce but he failed . The Kuomintang ( Nationalist ) military position steadily worsened and by 1949 , the Communists were victorious and drove the Nationalists from the onto the island of Taiwan . and other islands . Mao Zedong established the People ' s Republic of China ( PRC ) in mainland China , while the Republic of China remains in Taiwan to this day . Soviet Union . Joseph Stalin controlled the foreign policy of the Soviet Union , with Vyacheslav Molotov as his foreign minister . Their policy was neutrality until August 1939 , followed by friendly relations with Germany in order to carve up Eastern Europe . After he ignored repeated warnings , Stalin was stunned when Hitler invaded in June 1941 . Stalin quickly came to terms with Britain and the United States , cemented through a series of summit meetings . The U . S . and Britain supplied war materials in large quantity through Lend Lease . There was some coordination of military action , especially in summer 1944 . At war ' s end the central issue was whether Stalin would allow free elections in eastern Europe . France . French Republic . France and Britain collaborated closely in 1939 , and together declared war against Germany two days after it invaded Poland . Apart from the British Dominions ( Canada , Australia , New Zealand and South Africa ) , no independent nation joined their cause . Britain and France took a defensive posture , fearing German air attacks on cities . France hoped the Maginot Line would protect it from an invasion . There was little fighting between the fall of Poland in mid - September and the following spring ; it was the Phoney War in Britain or " Drôle de guerre " – the funny sort of war – in France . Britain tried several peace feelers , but Hitler did not respond . When Germany had its hands free for an attack in the west , its launched its Blitzkrieg against Denmark and Norway , easily pushing the British out . Then it invaded the Low Countries and tricked Britain and France into sending its best combat units deep into the Netherlands , where they became trapped in the Battle of France in May 1940 . The Royal Navy rescued over 300 , 000 British and French soldiers from Dunkirk , but left behind all the equipment . Paris fell to the Germans on 14 June 1940 , and the government surrendered on 24 June 1940 . Nazi Germany occupied three - fifths of France ' s territory , leaving the rest in the southeast to the new Vichy government , which was a bit more than a puppet state since it still had a navy . However nearly 2 million French soldiers became prisoners of war in Germany . They served as hostages and forced laborers in German factories . The United States suddenly realized Germany was on the verge of controlling practically all of Europe , and it determined to rapidly build up its small Army and Air Force , and expand its Navy . Sympathy with Britain was high , and many were willing to send munitions , but few Americans called for war . Vichy France . The fall of France in June 1940 brought a new regime known as Vichy France . Theoretically it was neutral , but in practice it was partly controlled by Germany until November 1942 , when Germany took full control . Vichy was intensely conservative and anti - Communist , but it was practically helpless with Germany controlling half of France directly and holding nearly two million French POWs as hostages . Vichy finally collapsed when the Germans fled in summer 1944 . The United States granted Vichy full diplomatic recognition , sending Admiral William D . Leahy to Paris as American ambassador . President Roosevelt hoped to use American influence to encourage those elements in the Vichy government opposed to military collaboration with Germany . Vichy still controlled its overseas colonies and Washington encouraged Vichy to resist German demands such as for air bases in Syria or to move war supplies through French North Africa . The essential American position was that France should take no action not explicitly required by the armistice terms that could adversely affect Allied efforts in the war . When Germany took full control the U . S . and Canada cut their ties . French fleet . Britain feared that the French naval fleet could end up in German hands and be used against its own naval forces , which were so vital to maintaining north Atlantic shipping and communications . Under the armistice , France had been allowed to retain the French Navy , the " Marine Nationale " , under strict conditions . Vichy pledged that the fleet would never fall into the hands of Germany , but refused to send the fleet beyond Germany ' s reach by sending it to Britain or to far away territories of the French empire such as the West Indies . Shortly after France gave up it attacked a large French naval contingent in Mers - el - Kebir , killing 1 , 297 French military personnel . Vichy severed diplomatic relations but did not declare war on Britain . Churchill also ordered French ships in British ports to be seized by the Royal Navy . The French squadron at Alexandria , Egypt , under Admiral René - Emile Godfroy , was effectively interned until 1943 . The American position towards Vichy France and Free France was inconsistent . President Roosevelt disliked and distrusted de Gaulle , and agreed with Ambassador Leahy ' s view that he was an " apprentice dictator . " North Africa . Preparing for a landing in North Africa in late 1942 , the US looked for a top French ally . It turned to Henri Giraud shortly before the landing on 8 November 1942 , but he had little local support . By hapstance the Vichy leader Admiral François Darlan was captured and supported the Americans . The Allies , with General Dwight D . Eisenhower in charge , signed a deal with Admiral Darlan on 22 November 1942 in which the Allies recognized Darlan as high commissioner for North Africa and West Africa . The Allied world was stunned at giving a high command to man who days before had been collaborating with the Nazis ; Roosevelt and Churchill supported Eisenhower , for he was following a plan that had been worked out in London and had been approved by Roosevelt and Churchill . Darlan was assassinated on 24 December 1942 , so Washington turned again towards Giraud , who was made High Commissioner of French North and West Africa . Giraud failed to build a political base and was displaced by the last man with any standing , de Gaulle . Free France . Free France was the insurgent French government based in London and the overseas French colonies and led by charismatic general Charles de Gaulle . He was the most senior French military officer to reject the June 1940 surrender ( " Armistice " ) and oppose the Vichy government of Marshall Pétain . From London on 18 June 1940 he gave an impassioned radio address exhorting the patriotic French people to resist Nazi Germany He organized the Free French Forces from soldiers that had escaped with the British at Dunkirk . With British military support the Free French gradually gained control of all French colonies except Indochina , which the Japanese controlled . The U . S . , Britain and Canada wanted Vichy to keep nominal control of the small islands of St . Pierre and Miquelon for reasons of prestige , but de Gaulle seized them anyway in late 1941 . When the British and Americans landed in France in June 1944 de Gaulle headed a government in exile based in London , but he continued to create diplomatic problems for the U . S . and Britain . He refused to allow French soldiers to land on D - Day , and insisted that France be treated as a great power by the other Allies , and that he himself was the only representative of France . Roosevelt disliked him , but he had Churchill ' s support . The U . S . and Britain allowed de Gaulle the honor of being the first to march into Paris at the head of his army after the Germans had fled . Neutrals . The main neutrals were Ireland , Portugal , Spain , Sweden , Switzerland and Turkey . The Soviet Union was officially neutral until June 1941 in Europe , and until August 1945 in Asia , when it attacked Japan in cooperation with the U . S . Latin America . The U . S . believed , falsely , that Germany had a master plan to subvert and take control of the economy of much of South America . Washington made anti - Nazi activity a high priority in the region . Three countries actively joined the war effort , while others passively broke relations or nominally declared war . Cuba declared war in December 1941 and actively helped in the defense of the Panama Canal . It did not send forces to Europe . Mexico declared war on Germany in 1942 after u - boats sank Mexican tankers carrying crude oil to the United States . It sent a 300 - man fighter squadron to the war against Japan in 1945 . Brazil declared war against Germany and Italy on 22 August 1942 and sent a 25 , 700 - man infantry force that fought mainly on the Italian front , from September 1944 to May 1945 . Its Navy and Air Force acted in the Atlantic Ocean . Argentina . Argentina hosted a strong , very - well - organized pro - Nazi element before the war that was controlled by German ambassadors . Brazil , Chile and Mexico had smaller movements . American foreign - policy worked to unite all of Latin America in a coalition against Germany . Argentina proved recalcitrant , and the US worked to undermine the Argentine government . The American policy backfired when the military seized power in a coup in 1943 . Relationships grew worse to the point that Washington seriously considered economic and diplomatic isolation of Argentina and tried unsuccessfully to keep it out of the United Nations in 1945 . Historians now agree that the supposed affinity between Argentina and Germany was greatly exaggerated . The Argentine government remained neutral until the last days of the war but quietly tolerated entry of Nazi leaders fleeing Germany , Belgium and Vichy France in 1945 . Indeed a conspiracy theory grew up after the war that greatly exaggerated the Nazi numbers and amount of gold they brought . Historians have shown there was little gold and probably not many Nazis , but the myths live on . Baltic States . Despite declaring neutrality the Baltic states were secretly assigned to the Soviet Sphere of influence via the Molotov - Ribbentrop pact and subsequently occupied by the Soviet Union and Nazi Germany . Diplomatic legations continued to represent the Baltic states throughout the period . Ireland . Ireland tried to be strictly neutral during the war , and refused to allow Britain to use bases . However it had large sales of exports to Britain , and tens of thousands joined the British armed forces . Portugal . Portugal was officially neutral , but in practice its dictator Salazar collaborated with the British and sold them rubber and tungsten . In late 1943 he allowed the Allies to establish air bases in the Azores to fight U - boats . He helped Spain avoid German control . Tungsten was a major product , and he sold to Germany until June 1944 , when the threat of a German attack on Portugal was minimal . He worked to regain control of East Timor after the Japanese seized it . He admitted several thousand Jewish refugees . Lisbon maintained air connections with Britain and the U . S . Lisbon was a hotbed of spies and served as the base for the International Red Cross in its distribution of relief supplies to POWs . Spain . Nazi leaders spent much of the war attempting to persuade the Franco regime to enter the war and allow a German army to march on Gibralter . The overtures provided futile . Franco was sympathetic but remained emphatically neutral . However , Spain did need to pay off its heavy debt to Germany . Therefore , Franco did provide various kinds of support to Italy and Germany . It sold Germany supplies , especially wolfram , the hard - to - find tungsten ore . It formed 45 , 000 volunteers into the Blue Division , which fought exclusively on the Eastern Front . Spain was neutral and traded as well with the Allies . Germany had an interest in seizing the key fortress of Gibralter , but Franco stationed his army at the French border to dissuade Germany from occupying the Iberian Peninsula . Franco displayed pragmatism and his determination to act principally in Spanish interests , in the face of Allied economic pressure , Axis military demands , and Spain ' s geographic isolation . As the war progressed he became more hard - line toward Germany and more accommodating to the Allies . Sweden . Sweden remained neutral during World War II , avoiding the fate of its neighbors , occupied Norway and defeated Finland . The dominant historiography for decades after the war ignored issues of the Holocaust and depended on the " small state realist " argument . It held that that neutrality and cooperation with Germany were necessary for survival , for Germany was vastly more powerful , concessions were limited and were only made where the threat was too great ; neutrality was bent but not broken ; national unity was paramount ; and in any case Sweden had the neutral right to trade with Germany . Germany needed Swedish iron and had nothing to gain — and much iron to lose — by an invasion . The nation was run by a unity government that included all major parties in the Riksdag . Its key leaders included Prime Minister Per Albin Hansson and Foreign Minister Christian Günther . King Gustav V had pro - Nazi proclivities that the government had to keep in check . Switzerland . Switzerland was neutral and did business with both sides . It mobilized its army to defend itself against any invasion . The Germans did make plans , but never invaded . Cut off from the Allies , Swiss trade was mostly with Germany , with Swiss banks a favourite place for Nazis to store their loot . The Swiss depended on German permission to import its food and fuel . Smuggling high precision tools and weapons ( such as jewel bearings , diamond dies , and chronographs ) to Britain took place on a large scale . Switzerland became a convenient center for spies and espionage . Swiss banks paid Germany 1 . 3 billion Swiss franks for gold ; Germany used the franks to buy supplies on the world market . However much of the gold was looted and the Allies warned Switzerland during the war . In 1947 Switzerland paid 250 million francs in exchange for the dropping of claims relating to the Swiss role in the gold transactions . Switzerland took in 48 , 000 refugees during the war , of whom 20 , 000 were Jewish . They also turned away about 40 , 000 applicants for refugee status . Switzerland ' s role regarding Nazi Germany became highly controversial in the 1990s . Wylie says , " Switzerland has been widely condemned for its part in the war . It has been accused of abetting genocide , by refusing to offer sanctuary to Hitler ' s victims , bankrolling the Nazi war economy , and callously profiting from Hitler ' s murderous actions by seizing the assets of those who perished in the death camps . " On the other hand , Churchill told his foreign minister in late 1944 : Turkey . Turkey was neutral in the war , but signed a treaty with Britain and France in October 1939 that said the Allies would defend Turkey if Germany attacked it . The deal was enhanced with loans of ₤41 million . An invasion was threatened in 1941 but did not happen and Ankara refused German requests to allow troops to cross its borders into Syria or into the USSR . Germany had been its largest trading partner before the war , and Turkey continued to do business with both sides . It purchased arms from both sides . The Allies tried to stop German purchases of chrome ( used in making better steel ) . Starting in 1942 the Allies provided military aid and pressed for a declaration of war . Turkey ' s president conferred with Roosevelt and Churchill at the Cairo Conference in November , 1943 , and promised to enter the war when it was fully armed . By August 1944 , with Germany nearing defeat , Turkey broke off relations . In February 1945 , it declared war on Germany and Japan , a symbolic move that allowed Turkey to join the future United Nations . Meanwhile relations with Moscow worsened , setting stage for the Truman Doctrine of 1947 and the start of the Cold War . Axis . The dictators of Germany and Italy , Hitler and Mussolini , had numerous conferences . Neither ever met with top Japanese leaders . The Japanese ambassador to Germany handled many of the negotiations between Germany and Japan , but his coded messages home were intercepted and decrypted by the United States starting in 1941 . The U . S . shared them with Britain . They revealed important German plans . Germany . Germany ' s foreign policy during the war involved the creation of allied governments under direct or indirect control from Berlin . A main goal was obtaining soldiers from the senior allies , such as Italy and Hungary , and millions of workers and ample food supplies from subservient allies such as Vichy France . By the fall of 1942 , there were 24 divisions from Romania on the Eastern Front , 10 from Italy and 10 from Hungary . When a country was no longer dependable , Germany would assume full control , as it did with France in 1942 , Italy in 1943 , and Hungary in 1944 . Full control allowed the Nazis to achieve their high priority of mass murdering all Jewish population . Although Japan was officially a powerful ally , the relationship was distant and there was little coordination or cooperation , such as Germany ' s refusal to share the secret formula for making synthetic oil from coal until late in the war . DiNardo argues that in Europe Germany ' s foreign - policy was dysfunctional during the war , as Hitler treated each ally separately , and refused to create any sort of combined staff that would synchronize policies , armaments , and strategies . Italy , Finland , Romania , and Hungary each dealt with Berlin separately , and never coordinated their activities . Germany was reluctant to share its powerful weapons systems , or to train Axis officers . There were some exceptions , such as the close collaboration between the German and Italian forces in North Africa . Hitler . Hitler devoted most of his attention during the war to military and diplomatic affairs . He frequently met with foreign leaders , such as the January 10 , 1943 he met with Rumanian Premier Marshal Ion Antonescu at German field headquarters , with top - ranking generals on both sides . On 9 August 1943 , Hitler summoned Tsar Boris III of Bulgaria to a stormy meeting at field headquarters , and demanded he declare war on Russia . The tsar refused , but did agree to declare war on far - away Britain . American news reports stated that Hitler tried to hit him and the tsar suffered a heart attack at the meeting ; he died three weeks later . Forced labour . German policy was not to use or build factories in occupied Eastern Europe but to move millions of workers into German factories and farms . Some were forced , some were voluntarily ( going in search of food ) , others were prisoners of war . They were closely watched , had poor food and housing , and were harshly treated . Their morale and levels of output were mediocre or poor . At the peak the forced labourers comprised 20 % of the German work force . Counting deaths and turnover , about 15 million individuals were forced labourers at one point or another during the war . Most came from Poland , Russia and other Eastern areas ; all were repatriated at war ' s end . Vichy France was one of the few countries that was able to have much influence on German policies , as it tried to protect the nearly two million French soldiers held as POWs inside Germany . Vichy arranged a deal whereby Germany would release one POW for every three Frenchmen who volunteered to work in Germany . Poland . Before the war in his speeches and writing , Hitler expressed anti - Polish sentiments and supported annexation of Polish territories In 1932 Hitler issued again territorial demands against Poland and as early as fall 1933 Hitler envisioned annexing Western Poland to Germany and creating a puppet state out of the rest . After gaining power until February 1939 Hitler tried to conceal his true intentions towards Poland and revealed them only to his closest associates In January 1934 Germany signed a non aggression pact with Poland followed by a trade treaty later in the year . By the spring Hitler was openly pondering what inducements he might have to offer to obtain a military alliance with Poland . Between 1919 and 1939 Poland pursued a policy of balance between Soviet Union and Nazi Germany and obtained non - aggression treaties with the former . In early 1939 Hitler wanted Poland to join the Anti - Comintern Pact as a satellite state in preparation for the German invasion of the Soviet Union . Steiner states that Hitler " wanted to broker an agreement with Colonel Beck , Poland ' s all - powerful foreign minister , which would bring Danzig and the Polish Corridor back into the Reich but keep Poland as a friend . " Hitler offered Poland a new non - aggression pact and recognition of its current frontiers if it agreed to permit the German - inhabited city of Danzig to return to Germany as well as allow an extraterritorial highway connecting Germany proper with Danzig and East Prussia going through Polish territory . Poland rejected the proposals . For Poland these demands meant losing independence ; Danzig in itself was not the primary issue . By March Hitler had given up on the Poles and in April began planning an invasion . Poland had few friends in the international arena . Two critical developments caught Poland by surprise . At the end of March 1939 Britain and France announced that if Germany invaded Poland they would declare war . In terms of helping Poland militarily in an actual war , everyone realized very little could be done because the British and French military thought that if Germany invaded " Polish resistance would collapse in the early stages of fighting . " Neither " was thinking of any major offensive action in the West . " Their hope was that the threat of a two - front war would deter Germany . Hitler believed that Britain and France were bluffing , but he handled the Soviet problem in late August , by an alliance agreement with Stalin , which included secret provisions to partition Poland — and indeed divide up much of eastern Europe . The British and French offer was not a bluff — they did indeed declare war on Germany when it invaded Poland on 1 September , but neither was in a position to provide serious help . Poland had a million - man army , but fell far short in terms of leadership , training , and equipment . The Polish military budget was about 2 % of Germany ' s ; its commanding general , Marshal Smigly - Rydz was not well prepared for the challenge . The Soviet Red Army then invaded Poland without a formal declaration of war on 17 September 1939 , immediately after the undeclared war between the Soviet Union and the Empire of Japan at the Battles of Khalkhin Gol ( Nomonhan ) in the Far East had ended . Poland was then partitioned between Germany and the Soviet Union . Worldwide Fascist groups . During the war Nazi Germany cultivated relationships with Fascist and extreme right groups in neutral and Allied controlled territory such as the Ossewabrandwag , an Afrikaner paramilitary organisation based on the Nazi Party . Italy . Allied policy was to be friendly with Benito Mussolini , the Fascist dictator of Italy , in the hopes he would either remain neutral or moderate Hitler ' s expansion plans . However in May 1939 , he joined the Axis with Germany , signing the Pact of Steel . When France was in the last stages of collapse Mussolini entered the war and gained some spoils . He brought along a powerful navy that could challenge the British for control of the Mediterranean . Roosevelt denounced the move : " On this 10th day of June , 1940 , the hand that held the dagger has struck it into the back of its neighbor . " Italy was poorly prepared for war and increasingly fell under Nazi dictation . Italian military efforts failed against Egypt , Greece , Ethiopia and Yugoslavia , and Germany had to intervene to rescue its neighbor . After the Allies invaded and took Sicily and southern Italy in 1943 , the regime collapsed . Mussolini was arrested and the King appointed General Pietro Badoglio as new Prime Minister . They switched sides , joined the Allies and banned the Fascist Party . However they procrastinated too long , and Germany moved in , occupying Italy north of Naples . German paratroopers rescued Mussolini and Hitler set him up as head of a puppet government the Italian Social Republic , often called the Salò Republic ; a civil war resulted . The Germans gave way slowly , for mountainous Italy offered many defensive opportunities . Britain by 1944 feared that Italy would become a Communist state under Soviet influence . It abandoned its original concept of British hegemony in Italy and substituted for it a policy of support for an independent Italy with a high degree of American influence . Balkans . Hitler , preparing to invade the Soviet Union , diverted attention to make sure the southern or Balkan flank was secure . Rumania was under heavy pressure , and was forced to cede 40 , 000 square miles of territory with 4 million people to the USSR , Hungary and Bulgaria ; German troops came in to protect the vital oil fields ( Germany ' s only source of oil besides the USSR ) . Rumania signed the Axis Pact and became a German ally ( November 1940 ) . So too did Hungary ( November 1940 ) and Bulgaria ( March , 1941 ) . Greece . By the middle of 1940 , Mussolini was jealous of Hitler ' s conquests and wanted to prove he could lead Italy to similar military triumphs . Italy had occupied Albania in the spring of 1939 as well as the Italian conquest of British Somaliland near Ethiopia . Mussolini also wanted to reassert Italy ' s interests in the Balkans , to secure bases from which British outposts in the eastern Mediterranean could be attacked . On 28 October 1940 , after Greece rejected an Italian ultimatum , Italy invaded Greece . The Greek army counterattacked and forced the Italians to retreat . By mid - December , 1940 , the Greeks occupied nearly a quarter of Albania , tying down 530 , 000 Italian troops . In March 1941 , a major Italian counterattack failed , humiliating Italian military pretensions . In April 1941 Germany came to Italy ' s aid by invading Greece through Bulgaria . The Greek army soon surrendered . Yugoslavia . Yugoslavia signed on as a German ally in March 1941 , but within hours an anti - Nazi coup , led by Serbians with British help , overthrew the prince regent , repudiated the Nazis , and installed the 17 year old heir as King Peter II . Germany marched in and set off an extremely bloody , long civil war that killed over a million people . The Independent State of Croatia ( NDH ) was heavily Catholic and conservative . It became an Axis ally ruled by the fascist militia known as the Ustaše ; it controlled Croatia , Bosnia and Herzegovina . Ethnic cleansing was its policy . The Ustaše murdered around 500 , 000 people ( mostly Serbs , along with 37 , 000 Jews ) , expelled 250 , 000 , and forced another 200 , 000 to convert to Catholicism . Kosovo was given to Albania ( then under Italian control ) . Macedonia went to Bulgaria and Vojvodina was given over to Hungary . Serbia became a German puppet state and was the cockpit of the resistance . Yugoslavia had a weak government in exile based in London that included the king . However , power inside the country was divided three ways between the Germans and their allies , and two Serbian resistance groups . The royalist anti - Communist Chetniks under Draža Mihailović , was nominally under the control of the government in exile . Chetniks were opposed to the Nazis but sometimes did collaborate with the Germans and Ustaša in their fierce guerrilla battles with the National Liberation Army , a Communist - controlled resistance headed by Josip Broz Tito . Tito ' s strength grew in 1943 , and Mihailović and the monarchists fell far behind . Churchill reversed course in December 1943 , ended his support for the royalist forces of Mihailović , and backed instead Tito . Tito drove out the Germans in 1945 and liquidated the Mihailovic forces . This allowed the formation of a Communist state of Yugoslavia that was independent of Moscow . Historians believe that Germany ' s large - scale intervention in the Balkans in spring 1941 probably delayed its invasion of Russia long enough to give the Soviets a chance to survive . Japan . Japan had conquered all of Manchuria and most of China by 1939 in the Second Sino - Japanese War , but the Allies refused to recognize the conquests . Japan joined the Axis with Germany , but shared little information . Japan depended on imports from the Allies for 90 % of its oil , and the cutoff of oil shipments in mid - 1941 left Japan with supplies for only a year or two of serious combat by its warships and warplanes unless it came to terms regarding China , or seized oil fields controlled by Britain and the Netherlands . The latter course meant war , and was urged by army officials who had been bloodied in border conflicts and were reluctant to engage the Soviets . Some admirals and many civilians , including Prime Minister Konoe Fumimaro , believed that a war with the U . S . would end in defeat . The alternative was loss of honor and power . Diplomats proposed political compromises in the form of the " Amau Doctrine " , dubbed the " Japanese Monroe Doctrine " which would have given the Japanese free rein with regard to China . These proposals were rejected by the U . S . ; the Japanese Army now demanded a military solution . Imperial conquests . Japan launched its own blitzkriegs in East Asia . In 1937 , the Japanese Army invaded and captured most of the coastal Chinese cities such as Shanghai . Japan took over French Indochina ( Vietnam , Laos , Cambodia ) , British Malaya ( Brunei , Malaysia , Singapore ) as well as the Dutch East Indies ( Indonesia ) . Thailand managed to stay independent by becoming a satellite state of Japan . In December 1941 to May 1942 , Japan sank major elements of the American , British and Dutch fleets , captured Hong Kong , Singapore , the Philippines and the Dutch East Indies , and reached the borders of India and began bombing Australia . Japan suddenly had achieved its goal of ruling the Greater East Asia Co - Prosperity Sphere . Imperial rule . The ideology of Japan ' s colonial empire , as it expanded dramatically during the war , contained two contradictory impulses . On the one hand , it preached the unity of the Greater East Asia Co - Prosperity Sphere , a coalition of Asian races , directed by Japan , against the imperialism of Britain , France , the Netherlands , United States , and Europe in general . This approach celebrated the spiritual values of the East in opposition to the crass materialism of the West . In practice , it was a euphemistic title for grabbing land and acquiring essential natural resources . The Japanese installed organizationally - minded bureaucrats and engineers to run their new empire , and they believed in ideals of efficiency , modernization , and engineering solutions to social problems . It was fascism based on technology , and rejected Western norms of democracy . After 1945 , the engineers and bureaucrats took over , and turned the wartime techno - fascism into entrepreneurial management skills . Japan set up puppet regimes in Manchuria ( " Manchukuo " ) and China ; proper ; they vanished at the end of the war . The Japanese Army operated ruthless governments in most of the conquered areas , but paid more favorable attention to the Dutch East Indies . The main goal was to obtain oil , but Japan sponsored an Indonesian nationalist movement under Sukarno . Sukarno finally came to power in the late 1940s after several years of battling the Dutch . The Dutch destroyed their oil wells but the Japanese reopened them . However most of the tankers taking oil to Japan were sunk by American submarines , so Japan ' s oil shortage became increasing acute . Puppet states in China . Japan set up puppet regimes in Manchuria ( " Manchukuo " ) and China ; proper ; they vanished at the end of the war . Manchuria , the historic homeland of the Manchu dynasty , had an ambiguous character after 1912 . It was run by local warlords . The Japanese Army seized control in 1931 , and set up a puppet state of Manchukuo in 1932 for the 34 , 000 , 000 inhabitants . Other areas were added , and over 800 , 000 Japanese moved in as administrators . The nominal ruler was Puyi , who as a small child had been the last Emperor of China . He was deposed during the revolution of 1911 , and now the Japanese brought him back in a powerless role . Only Axis countries recognized Manchukuo . The United States in 1932 announced the Stimson Doctrine stating that it would never recognize Japanese sovereignty . Japan modernized the economy and operated it as a satellite to the Japanese economy . It was out of range of American bombers , so its factories continued their output to the end . Manchukuo was returned to China in 1945 . When Japan seized control of China proper in 1937 – 38 , the Japanese Central China Expeditionary Army set up the Reorganized National Government of China , a puppet state , under the nominal leadership of Wang Ching - wei ( 1883 – 1944 ) . It was based in Nanjing . The Japanese were in full control ; the puppet state declared war on the Allies in 1943 . Wang was allowed to administer the International Settlement in Shanghai . The puppet state had an army of 900 , 000 soldiers , and was positioned against the Nationalist army under Chiang Kai - shek . It did little fighting . Military defeats . The attack on Pearl Harbor , initially appeared to be a major success that knocked out the American battle fleet — but it missed the aircraft carriers that were at sea and ignored vital shore facilities whose destruction could have crippled US Pacific operations . Ultimately , the attack proved a long - term strategic disaster that actually inflicted relatively little significant long - term damage while provoking the United States to seek revenge in an all - out total war in which no terms short of unconditional surrender would be entertained . However as Admiral Yamamoto warned , Japan ' s six - month window of military advantage following Pearl Harbor ended with the Japanese Navy ' s offensive ability being crippled at the hands of the American Navy in the Battle of Midway . As the war became one of mass production and logistics , the U . S . built a far stronger navy with more numerous warplanes , and a superior communications and logistics system . The Japanese had stretched too far and were unable to supply its forward bases — many soldiers died of starvation . Japan built warplanes in large quantity but the quality plunged , and the performance of poorly trained pilots spiraled downward . The Imperial Navy lost a series of major battles , from Midway ( 1942 ) to the Philippine Sea ( 1944 ) and Leyte Gulf ( 1945 ) , which put American long - range B - 29 bombers in range . A series of massive raids burned out much of Tokyo and 64 major industrial cities beginning in March 1945 while Operation Starvation seriously disrupted the nation ' s vital internal shipping lanes . Regardless of how the war was becoming hopeless , the circle around the Emperor held fast and refused to open negotiations . Finally in August , two atomic bombs and the Soviet invasion of Manchuria demonstrated the cause was futile , and Hirohito authorized a surrender whereby he kept his throne . Deaths . Total Japanese military fatalities between 1937 and 1945 were 2 . 1 million ; most came in the last year of the war . Starvation or malnutrition - related illness accounted for roughly 80 percent of Japanese military deaths in the Philippines , and 50 percent of military fatalities in China . The aerial bombing of a total of 65 Japanese cities appears to have taken a minimum of 400 , 000 and possibly closer to 600 , 000 civilian lives ( over 100 , 000 in Tokyo alone , over 200 , 000 in Hiroshima and Nagasaki combined , and 80 , 000 – 150 , 000 civilian deaths in the battle of Okinawa ) . Civilian death among settlers who died attempting to return to Japan from Manchuria in the winter of 1945 were probably around 100 , 000 . Finland . Although Finland officially was not a part of the Axis , it was aligned with Germany in a war against the Soviet Union . The August 1939 Molotov - Ribbentrop Pact between Germany and the Soviet Union contained a secret protocol dividing much of eastern Europe and assigning Finland to the Soviet sphere of influence . Finland before 1918 had been a province of Russia , and many Finnish speakers lived in neighboring parts of Russia . After unsuccessfully attempting to force territorial and other concessions on the Finns , the Soviet Union invaded Finland in November 1939 during the Winter War , intending to establish a communist puppet government in Finland . Finland won very wide popular support in Britain and the United States . The arms - length collaboration with Germany stemmed from a precarious balance struck by the Finns in order to avoid antagonizing Britain and the United States . In the end Britain declared war to satisfy the needs of its Soviet policy , but did not engage in combat against Finland . Finland concluded armistice negotiations with the USSR under strong German pressure to continue the war , while British and American acted in accord with their own alliances with the Soviets . Soviet success in Finland would threaten Germany ' s iron - ore supplies and offered the prospect of Allied interference in the region . The Soviets overwhelmed the Finnish resistance in the Winter War , and a peace treaty was signed in March 1940 . It ceded some Finnish territory to the Soviet Union , including the Karelian Isthmus , containing Finland ' s second - largest city , Viipuri , and the critical defensive structure of the Mannerheim Line . After the Winter War war , Finland sought protection and support from the Britain and Sweden without success . Finland drew closer to Germany , first with the intent of enlisting German support as a counterweight to thwart continuing Soviet pressure , and later to help regain lost territories . Finland declared war against the Soviet Union on 25 June 1941 in what is called the Continuation War . To meet Stalin ' s demands , Britain reluctantly declared war on Finland on 6 December 1941 , although no other military operations followed . War was never declared between Finland and the United States , though relations were severed between the two countries in 1944 as a result of the Ryti - Ribbentrop Agreement . Finland maintained command of its armed forces and pursued war objectives independently of Germany . Germans and Finns did work closely together during Operation Silverfox , a joint offensive against Murmansk . Finland refused German requests to participate actively in the Siege of Leningrad , and also granted asylum to Jews , while Jewish soldiers continued to serve in its army . The relationship between Finland and Germany more closely resembled an alliance during the six weeks of the Ryti - Ribbentrop Agreement , which was presented as a German condition for help with munitions and air support , as the Soviet offensive coordinated with D - Day threatened Finland with complete occupation . The agreement bound Finland not to seek a separate peace with Moscow . After Soviet offensives were fought to a standstill , Ryti ' s successor as president , Marshall Mannerheim , dismissed the agreement and opened secret negotiations with the Soviets , which resulted in the Moscow Armistice on 19 September 1944 . Under the terms of the armistice , Finland was obliged to expel German troops from Finnish territory , which resulted in the Lapland War . Finland signed a peace treaty with the Allied powers in 1947 . Governments in Exile . Britain welcomed governments in exile to set up their headquarters in London whilst others were set up in neutral or other allied territory . Recognition for these bodies would vary and change over time . Poland . Most Polish leaders fled to Romania , where they were interred . Other leaders escaped to France , and later to London , where the Polish government - in - exile was set up by General Sikorski . It was recognized by the Allies until 1944 . The underground resistance movement formed inside Poland ; it nominally reported to the government in exile . During the war about 400 , 000 Poles joined the underground Polish Home Army , about 200 , 000 went into combat on western fronts in units loyal to the Polish government in exile , and about 300 , 000 in the last stages of the war . Since the start of the war the body protested on the international stage against the German occupation of their territory and the treatment of their civilian population . In 1940 the Polish Ministry of Information produced a list of those it believed had been murdered by the Nazis . Later in 1942 Poland addressed the governments of the United Nations with a publication entitled " The Mass Extermination of Jews in German Occupied Poland " . Norway . Norway in 1939 had the world ' s fourth largest merchant fleet , at 4 . 8 million tons , including a fifth of the world ' s oil tankers . The Germans captured about 20 % of the fleet but the remainder , about 1000 ships , were taken over by the government . Although half the ships were sunk , the earnings paid the expenses of the government . Netherlands . The government in 1940 fled to London , where it had command of some colonies as well as the Dutch navy and merchant marine . When they arrived in London the Government in exile considered itself still neutral but found its desire for the liberation of the Netherlands coinciding with the war aims of the Allies . After the fall of France the Dutch Prime Minister Dirk Jan de Geer advocated negotiating a separate peace between the Netherlands and the Third Reich . Queen Wilhelmina fearing that the loss of the Dutch East Indies to Japan would be a term of any treaty vetoed any agreement . On 3 September 1940 the Queen dismissed her prime minister and replaced him with Pieter Sjoerds Gerbrandy , who worked with Churchill and Roosevelt on ways to smooth the path for an American entry . Aruba together with Curaçao the then world - class exporting oil refineries were the main suppliers of refined products to the Allies . Aruba became a British protectorate from 1940 to 1942 and a US protectorate from 1942 to 1945 . On November 23 , 1941 , under an agreement with the Netherlands government - in - exile , the United States occupied Dutch Guiana to protect the bauxite mines . Czechoslovakia . The Czechoslovak government - in - exile was an informal title given to the Czechoslovak National Liberation Committee originally created by the former Czechoslovak President , Edvard Beneš in Paris in October 1939 . Unsuccessful negotiations with France for diplomatic status , as well as the impending Nazi occupation of France , forced the Committee to withdraw to London in 1940 . The body was eventually considered , by those countries that recognized it , as the legal continuation of the First Republic of Czechoslovakia . Belgium . The German invasion lasted only 18 days in 1939 before the Belgian army surrendered . The king remained behind , but the government escaped to France and then to England in 1940 . Belgium was liberated in late 1944 . Belgium had two holdings in Africa , the very large colony of the Belgian Congo and the mandate of Ruanda - Urundi . The Belgian Congo was not occupied and remained loyal to the Allies as a useful economic asset . The government in exile sold 3 . 4 million pounds of uranium ore from the Congo to the U . S . for the atomic bomb . Troops from the Belgian Congo participated in the East African Campaign against the Italians . The colonial " Force Publique " also served in other theatres alongside British forces . Korea . Based in the Chinese city of Shanghai and later Chongqing the Provisional Government of the Republic of Korea acted as the Korean government - in - exile from 13 April 1919 until the Republic of Korea was established in 1948 .