Question: When did Hitler issue the directive to prepare to invade the Soviet Union?
About the article "World War II", section "Axis attack on the USSR (1941)".

Candidate passages:
Hitler had been considering war with the Soviet Union since July 1940.
However, after Germany entered the Axis Pact with Japan and Italy, in October 1940, the Soviet Union explored a possible entry into the Axis themselves.
After long discussions and proposals, Germany presented the Soviets with a draft written Axis pact agreement defining the world spheres of influence of the four proposed Axis powers (Japan, Germany, Soviet Union, Italy).
Eleven days later, the Soviets presented a Stalin-drafted written counterproposal where they would accept the four power pact, but it included Soviet rights to Bulgaria and a world sphere of influence focus on the area around modern Iraq and Iran.
The Soviet offer came concurrently with massive economic efforts to Germany.
The Soviets promised by May 11, 1941 the delivery of 2.5 million tons of grain—1 million tons above its current obligations.
They also promised full compensation for the Volksdeutsche property claims.
Shortly thereafter, Hitler issued a secret directive on the eventual attempts to invade the Soviet Union.
Stalin's written draft counter-proposal was ignored, which worsened tensions between the countries. 
Hitler had already issued a secret directive on the eventual attempts to invade the Soviet Union.
However, he had not abandoned hopes, talking still of a "great worldwide coalition that stretched from Yokohama to Spain", but he had resolved to not give up the Balkans.
In the meantime, the Soviets immediately summoned the Bulgarian ambassador to the Foreign Ministry, stating that the Soviets needed to do a deal with the Bulgarians before they joined the Axis and that Germany was attempting to make them a puppet state.
The Bulgarians turned down the offer and leaked it to Germany.
Hitler still hoped to dissuade Stalin from giving guarantees to Bulgaria if they could solve the Bosporus issue and pressed the Bulgarian ambassador that the Soviets could be persuaded against resistance if the Bulgarians joined the pact, while warning about the horrors of a Soviet occupation.
The Soviets meanwhile produced the biggest surprise.
In an unannounced November 25 visit in Sofia, the Soviets told the Bulgarian Prime Minister that, if Bulgaria permitted the Soviets troop transfer access, the Soviets were prepared to drop their objections to Bulgaria's entry into the Axis and, most surprisingly, stated that it likely would not be an issue as it would "very probably, almost certainly" lead to the Soviets' own entry into the Axis.
The stunned Bulgarian Prime Minister stated that this required further contemplation.
The Soviet negotiators had concluded that the Bulgarian government "is already committed to Germany to the hilt."
Joseph Stalin's own reputation as a brutal dictator contributed both to the Nazis' justification of their assault and their faith in success.
In the late 1930s, many competent and experienced military officers were killed in the Great Purge, leaving the Red Army weakened and leaderless.
The Nazis often emphasized the Soviet regime's brutality when targeting the Slavs with propaganda.
German propaganda claimed the Red Army was preparing to attack them, and their own invasion was thus presented as a preemptive strike.
In the summer of 1940, when German raw materials crises and a potential collision with the Soviet Union over territory in the Balkans arose, an eventual invasion of the Soviet Union looked increasingly like Hitler's only solution.
While no concrete plans were yet made, Hitler told one of his generals in June that the victories in western Europe "finally freed his hands for his important real task: the showdown with Bolshevism", although German generals told Hitler that occupying Western Russia would create "more of a drain than a relief for Germany's economic situation."
The "Führer" anticipated additional benefits: When the Soviet Union was defeated, the labor shortage in German industry could be relieved by demobilization of many soldiers.
Ukraine would be a reliable source of agricultural products.
Having the Soviet Union as a source of forced labor under German rule would vastly improve Germany's geostrategic position.
Defeat of the Soviet Union would further isolate the Allies, especially the United Kingdom.
The German economy needed more oil – controlling the Baku Oilfields would achieve this; as Albert Speer, the German Minister for Armaments and War Production, later said in his post-war interrogation, "the need for oil certainly was a prime motive" in the decision to invade.
On 5 December 1940, Hitler received the final military plans for the invasion which were drawn since July 1940 already under the codename Operation Otto.
He approved them all, with the start scheduled for May 1941.
On 18 December, Hitler signed War Directive No.
21 to the German High Command for an operation now codenamed "Operation Barbarossa" stating: "The German "Wehrmacht" must be prepared to crush Soviet Russia in a quick campaign."
The operation was named after Emperor Frederick Barbarossa of the Holy Roman Empire, a leader of the Third Crusade in the 12th century.
The invasion was set for 15 May 1941.
The plan for "Barbarossa" assumed that the "Wehrmacht" would emerge victorious if it could destroy the bulk of the Red Army west of the Western Dvina and Dnieper Rivers.
This assumption would be proven fatally wrong less than a month into the invasion.
In a 1978 essay "Das Russlandbild der führenden deutschen Militärs" ("The Picture of Russia held by the Leadership of the German Military"), the German historian Andreas Hillgruber examined the views about the Soviet Union held by the German military elite in the period June 1940 to June 1941.
According to Hillgruber, the following were the case: The "Wehrmacht" was ill-informed about the Soviet Union, especially the military and the economy.
Because of the paucity of information, "Wehrmacht" thinking about the Soviet Union was based upon traditional German stereotypes of Russia as a primitive, backward "Asiatic" country, a "colossus with feet of clay" that lacked the strength to stand up to a superior opponent.
The leadership of the "Wehrmacht" viewed war with the Soviet Union from an extremely narrow military viewpoint with little consideration given to politics, the economy, or culture.
The industrial capacity of the Soviet Union was not considered at all as a factor that might influence the outcome of a German-Soviet war.
The average soldier in the Red Army was considered brave and tough, but the Red Army officer corps were held in contempt.
The "Wehrmacht" leadership after the victory over France was in a state of hubris with the "Wehrmacht" being seen as more or less invincible.
As such, it was assumed that the Soviet Union was destined to be defeated, and that it would take Germany between six to eight weeks to destroy the Soviet Union.
Hillgruber argued that these assumptions about the Soviet Union shared by the entire military elite allowed Hitler to push through a "war of annihilation" against the Soviet Union with the assistance of "several military leaders", even though it was quite clear to the military that such a war would violate all standards of civilized warfare and would be waged in the most inhumane fashion possible.
In the Soviet Union, speaking to his generals in December, Stalin mentioned Hitler's references to an attack on the Soviet Union in "Mein Kampf", and said they must always be ready to repulse a German attack, and that Hitler thought the Red Army would need four years to ready itself.
Hence, "we must be ready much earlier" and "we will try to delay the war for another two years".
In autumn 1940, high-ranking German officials drafted a memorandum on the dangers of an invasion of the Soviet Union.
They said Ukraine, Belorussia and the Baltic States would end up as only a further economic burden for Germany.
Another German official argued that the Soviets in their current bureaucratic form were harmless, the occupation would not produce a gain for Germany and "why should it not stew next to us in its damp Bolshevism?
"Hitler ignored German economic naysayers, and told Hermann Göring, the chief of the "Luftwaffe", that everyone on all sides was always raising economic misgivings against a threatening war with Russia.
From now on he was not going to listen to any more of that kind of talk or he was going to stop up his ears in order to get his peace of mind.
This was passed on to General Georg Thomas, who had been preparing reports on the negative economic consequences of an invasion of the Soviet Union—that it would be a net economic drain unless it was captured intact.
Beginning in March 1941, Göring's Green Folder laid out details of the Soviet Union's proposed economic disposal after the invasion.
The entire urban population of the invaded land was to be starved to death, thus creating an agricultural surplus to feed Germany and allowing the urban population's replacement by a German upper class.
In the summer of 1941, German Nazi-ideologist Alfred Rosenberg suggested that conquered Soviet territory should be administered in the following "Reichskommissariates": Ostland (The Baltic countries and Belarus, extended eastward by about 500 km) Ukraine (Ukraine, enlarged eastwards to the Volga) Kaukasus (Southern Russia and the Caucasus region) Moskowien (Moscow metropolitan area and the rest of European Russia) Turkestan (Central Asian republics and territories) Nazi policy aimed to destroy the Soviet Union as a political entity in accordance with the geopolitical "Lebensraum" ideal (""Drang nach Osten"") for the benefit of future generations of the "Nordic Aryan master race".
Operation "Barbarossa" was to combine a northern assault towards Leningrad, a symbolic capturing of Moscow, and an economic strategy of seizing oil fields in the south beyond Ukraine.
Hitler and his generals disagreed on which of these aspects should take priority and where Germany should focus its energies; deciding on priorities required a compromise.
While planning "Barbarossa" in 1940–1941, in many discussions with his generals, Hitler repeated his order: "Leningrad first, the Donetsk Basin second, Moscow third".
Hitler believed Moscow was of "no great importance" in the defeat of the Soviet Union, and instead believed victory would come with the destruction of the Red Army west of the capital.
This later led to conflict between Hitler and several German senior officers including Heinz Guderian, Gerhard Engel, Fedor von Bock and Franz Halder, who believed the decisive victory could only be delivered at Moscow.
Hitler was impatient to get on with his long-desired invasion of the east.
He was convinced Britain would sue for peace, once the Germans triumphed in the Soviet Union, the real area of Germany's interests.
Halder noted in his diaries that, by destroying the Soviet Union, Germany would destroy Britain's hope of victory.
Hitler had grown overconfident from his rapid success in Western Europe and the Red Army's ineptitude in the Winter War against Finland in 1939–1940.
He expected victory within a few months and therefore did not prepare for a war lasting into the winter.
This meant his troops lacked adequate warm clothing and preparations for a longer campaign when they began their attack.
The assumption that the Soviet Union would quickly capitulate would prove to be his undoing. 
Relations between the Soviet Union and the major Axis powers were generally hostile before 1938.
In the Spanish Civil War, the Soviet Union gave military aid to the Second Spanish Republic, against Spanish Nationalist forces, which were assisted by Germany and Italy.
However, the Nationalist forces were victorious.
The Soviets suffered another political defeat when their ally Czechoslovakia was partitioned and taken over by Germany in 1938-39.
In 1938 and 1939, the USSR fought and defeated Japan in two separate border conflicts, at Lake Khasan and Khalkhin Gol.
The latter was a major Soviet victory that led the Japanese Army to avoid war with the Soviets and insteas call for expansion south.
In 1939 the Soviet Union considered forming an alliance with either Britain and France or with Germany.
When negotiations with Britain and France failed, they turned to Germany and signed the Molotov-Ribbentrop Pact in August 1939.
Germany was now freed from the risk of war with the Soviets, and was assured a supply of oil.
This included a secret protocol whereby the independent countries of Finland, Estonia, Latvia, Lithuania, Poland, and Romania were divided into spheres of interest of the parties.
The Soviet Union had been forced to cede Western Belarus and Western Ukraine to Poland after losing the Soviet-Polish War of 1919–1921, and the Soviet Union sought to regain those territories.
On 1 September, barely a week after the pact had been signed, Germany invaded Poland.
The Soviet Union on 17 September and on 28 September signed a secret treaty with Nazi Germany to arrange coordination of fighting against Polish resistance.
The Soviets targeted intelligence, entrepreneurs, and officers, committing a string of atrocities that culminated in the Katyn massacre and mass relocation to the Gulag in Siberia.
Soon thereafter, the Soviet Union occupied the Baltic countries of Estonia, Latvia, and Lithuania, and annexed Bessarabia and Northern Bukovina from Romania.
The Soviet Union attacked Finland on 30 November 1939, which started the Winter War.
Finnish defences prevented an all-out invasion, resulting in an interim peace, but Finland was forced to cede strategically important border areas near Leningrad.
The Soviet Union provided material support to Germany in the war effort against Western Europe through a pair of commercial agreements, the first in 1939 and the second in 1940, which involved exports of raw materials (phosphates, chromium and iron ore, mineral oil, grain, cotton, and rubber).
These and other export goods transported through Soviet and occupied Polish territories allowed Germany to circumvent the British naval blockade.
In October and November 1940, German-Soviet talks about the potential of joining the Axis took place in Berlin.
Joseph Stalin later personally countered with a separate proposal in a letter later in November that contained several secret protocols, including that "the area south of Batum and Baku in the general direction of the Persian Gulf is recognized as the center of aspirations of the Soviet Union", referring to an area approximating present day Iraq and Iran, and a Soviet claim to Bulgaria.
Hitler never responded to Stalin's letter.
Shortly thereafter, Hitler issued a secret directive on the eventual attempt to invade the Soviet Union.
Germany ended the Molotov-Ribbentrop Pact by invading the Soviet Union in Operation Barbarossa on 22 June 1941.
That resulted in the Soviet Union becoming one of the main members of the Allies.
Germany then revived its Anti-Comintern Pact, enlisting many European and Asian countries in opposition to the Soviet Union.
The Soviet Union and Japan remained neutral towards each other for most of the war by the Soviet-Japanese Neutrality Pact.
The Soviet Union ended the Soviet-Japanese Neutrality Pact by invading Manchukuo on 8 August 1945, due to agreements reached at the Yalta Conference with Roosevelt and Churchill. 
Hitler made the fateful decision to invade Russia in early 1941, but was delayed by the need to take control of the Balkans.
Europe was not big enough for both Hitler and Stalin, and Hitler realized the sooner he moved the less risk of American involvement.
Stalin thought he had a long-term partnership and rejected information coming from all directions that Germany was about to invade in June 1941.
As a result, the Russians were poorly prepared and suffered huge losses, being pushed back to Moscow by December before holding the line.
Hitler imagined that the Soviet Union was a hollow shell that would easily collapse, like France.
He therefore had not prepared for a long war, and did not have sufficient winter clothing and gear for his soldiers.
Weinberg (1994) argues that decisions concerning the invasion of the Soviet Union in June 1941 must be understood in the broader context of Hitler's ideological motivations and long-term goals.
Although Hitler had decided to invade the Soviet Union as early as 1940, German resources never reflected this; armaments production, tank and aircraft construction, and logistical preparations focused on the West.
Diplomatic activity was similarly skewed; Hitler granted Stalin any territory he wanted (such as Lithuania), knowing they would soon be at war and Germany would reclaim it anyway.
Hitler, blinded by his racist prejudices against Slavs, believed the Eastern campaign would be quick and easy.
His real strategic concern was Great Britain and the United States, and his planning consistently demonstrated this.