Causes of World War II

Source: Wikipedia, the free encyclopedia.

German battleship Schleswig-Holstein attacks Westerplatte
at the start of the war, September 1, 1939
The destroyer USS Shaw explodes during the attack on Pearl Harbor, December 7, 1941

The causes of

Italian aggression against Ethiopia
.

During the interwar period, deep anger arose in the Weimar Republic over the conditions of the 1919 Treaty of Versailles, which punished Germany for its role in World War I with heavy financial reparations and severe limitations on its military that were intended to prevent it from becoming a military power again. The demilitarisation of the Rhineland, the prohibition of German unification with Austria, and the loss of its overseas colonies as well as some 12% of its pre-war land area and population all provoked strong currents of revanchism in German politics.

During the worldwide economic crisis of the

Imperial Japan against China
.

At first, the aggressive moves met with only feeble and ineffectual policies of

Munich Conference, which formally approved Germany's annexation of the Sudetenland
from Czechoslovakia. Hitler promised it was his last territorial claim, nevertheless in early 1939, he became even more aggressive, and European governments finally realised that appeasement would not guarantee peace but by then it was too late.

Britain and France rejected diplomatic efforts to form a military alliance with the Soviet Union, and Hitler instead offered Stalin a better deal in the Molotov–Ribbentrop Pact of August 1939. An alliance formed by Germany, Italy, and Japan led to the establishment of the Axis powers.

Ultimate causes

Legacies of World War I

"The Big Four" made all the major decisions at the Paris Peace Conference (from left to right, David Lloyd George of Britain, Vittorio Emanuele Orlando of Italy, Georges Clemenceau of France, Woodrow Wilson of the U.S.)

By the end of

War Guilt Clause was the first step to satisfying revenge for the victor countries, especially France, against Germany. Roy H. Ginsberg argued, "France was greatly weakened and, in its weakness and fear of a resurgent Germany, sought to isolate and punish Germany... French revenge would come back to haunt France during the Nazi invasion and occupation twenty years later".[4]

Weimar Germany

The two main provisions of the French security agenda were war reparations from Germany in the form of money and coal and a detached German Rhineland. The German (Weimar Republic) government printed excess currency, which created inflation, to compensate for the lack of funds, and it borrowed money from the United States. Reparations from Germany were needed to stabilise the French economy.[5] France also demanded for Germany to give France its coal supply from the Ruhr to compensate for the destruction of French coal mines during the war. The French demanded an amount of coal that was a "technical impossibility" for the Germans to pay.[6] France also insisted on the demilitarisation of the German Rhineland in the hope of hindering any possibility of a future German attack and giving France a physical security barrier between itself and Germany.[7] The inordinate amount of reparations, coal payments and the principle of a demilitarised Rhineland were largely viewed by the Germans as insulting and unreasonable.

The resulting Treaty of Versailles brought a formal end to the war but was judged by governments on all sides of the conflict. It was neither lenient enough to appease Germany nor harsh enough to prevent it from becoming a dominant continental power again.[8] The German people largely viewed the treaty as placing the blame, or "war guilt", on Germany and Austria-Hungary and as punishing them for their "responsibility", rather than working out an agreement that would assure long-term peace. The treaty imposed harsh monetary reparations and requirements for demilitarisation and territorial dismemberment, caused mass ethnic resettlement and separated millions of ethnic Germans into neighbouring countries.

In the effort to pay war reparations to Britain and France, the

national hero
by the German population.

During the war,

Dolchstosslegende
("stab-in-the-back myth"), which gave the Nazis another propaganda tool.

territorial changes in Europe
after World War I (as of 1922)

The demilitarised Rhineland and the additional cutbacks on military also infuriated the Germans. Although France logically wanted the Rhineland to be a neutral zone, France had the power to make their desire happen, which merely exacerbated German resentment of the French. In addition, the Treaty of Versailles dissolved the German general staff, and possession of navy ships, aircraft, poison gas, tanks and heavy artillery was also made illegal.[7] The humiliation of being bossed around by the victor countries, especially France, and being stripped of their prized military made the Germans resent the Weimar Republic and idolise anyone who stood up to it.[12] Austria also found the treaty unjust, which encouraged Hitler's popularity.

The conditions generated bitter resentment towards the war's victors, who had promised the Germans that US President

November criminals", who later assumed office in the new Weimar Republic. The Japanese also started to express resentment against Western Europe for how they were treated during the negotiations of the Treaty of Versailles. The Japanese proposition to discuss the issue of racial equality was not put in the final draft because of many other Allies, and the Japanese participation in the war caused little reward for the country.[13] The war's economic and psychological legacies persisted well into the Interwar period
.

Failure of the League of Nations

The

that was maintained by strong armies and secret agreements. Under the new philosophy, the League would act as a government of governments, with the role of settling disputes between individual nations in an open and legalist forum. Despite Wilson's advocacy, the United States never joined the League of Nations.

The League lacked an armed force of its own and so depended on member nations to enforce its resolutions, uphold economic sanctions that the League ordered or provide an army when needed for the League to use. However, individual governments were often very reluctant to do so. After numerous notable successes and some early failures in the 1920s, the League ultimately proved incapable of preventing aggression by the

Axis Powers in the 1930s. The reliance upon unanimous decisions, the lack of an independent body of armed forces and the continued self-interest of its leading members meant that the failure was arguably inevitable.[15][16]

Expansionism and militarism

Expansionism is the doctrine of expanding the territorial base or economic influence of a country, usually by means of military aggression. Militarism is the principle or policy of maintaining a strong military capability to use aggressively to expand national interests and/or values, with the view that military efficiency is the supreme ideal of a state.[17]

The Treaty of Versailles and the League of Nations had sought to stifle expansionist and militarist policies by all actors, but the conditions imposed by their creators imposed on the world's new geopolitical situation and the technological circumstances of the era only emboldened the re-emergence of those ideologies during the Interwar Period. By the early 1930s, militaristic and aggressive national ideologies prevailed in

Italy.[18] The attitude fuelled advancements in military technology, subversive propaganda and ultimately territorial expansion. It has been observed that the leaders of countries that have been suddenly militarised often feel a need to prove that their armies are formidable, which was often a contributing factor in the start of conflicts such as the Second Italo-Ethiopian War and the Second Sino-Japanese War.[19]

Italy and its colonial possessions in 1940

In Italy,

ancient Romans.[20]

Under the Nazi regime, Germany began its own program of expansion that sought to restore its "rightful" boundaries. As a prelude toward its goals, the

German-Austria, a rump state of Austria-Hungary, was blocked by the Allies, despite the large majority of Austrians
supporting the idea.

During the Weimar Republic (1919–1933), the

irredentist
sentiments and put Germany on a collision course for war with its immediate neighbours.

The Japanese march into Zhengyangmen, Beijing, after they captured the city in July 1937

In Asia, the

February 26 Incident in which junior officers attempted a coup d'état and killed leading members of the Japanese government. In the 1930s, the Great Depression
wrecked Japan's economy and gave radical elements within the Japanese military the chance to force the entire military into working towards the conquest of all of Asia.

For example, in 1931, the

Mukden Incident, which sparked the invasion of Manchuria and its transformation into the Japanese puppet state of Manchukuo
.

Germans vs. Slavs

Twentieth-century events marked the culmination of a millennium-long process of intermingling between Germans and

Social Darwinist theories framed the coexistence as a "Teuton vs. Slav" struggle for domination, land, and limited resources.[22] Integrating these ideas into their own worldview, the Nazis believed that the Germans, the "Aryan race", were the master race and that the Slavs were inferior.[23]

Japan's seizure of resources and markets

Japanese occupation of China in 1937

Other than a few coal and iron deposits and a small oil field on

Sakhalin Island, Japan lacked strategic mineral resources. In the early 20th century, in the Russo-Japanese War, Japan had succeeded in pushing back the East Asian expansion of the Russian Empire in competition for Korea and Manchuria
.

Japan's goal after 1931 was economic dominance of most of East Asia, often expressed in the

Joseph C. Grew
, in a formal address to the America-Japan Society, stated that

the new order in East Asia has appeared to include, among other things, depriving Americans of their long established rights in China, and to this the American people are opposed.... American rights and interests in China are being impaired or destroyed by the policies and actions of the Japanese authorities in China.[25]

In 1931, Japan invaded Manchuria and China proper. Under the guise of the Greater East Asia Co-Prosperity Sphere, with slogans such as "Asia for the Asians!", Japan sought to remove the Western powers' influence in China and replace it with Japanese domination.[26][27]

The ongoing conflict in China led to a deepening conflict with the US in which public opinion was alarmed by events such as the

Franklin Roosevelt
freeze all Japanese assets in the US. The intended consequence was to halt oil shipments from the US to Japan, which supplied 80 percent of Japanese oil imports. The Netherlands and Britain followed suit.

With oil reserves that would last only a year and a half during peacetime and much less during wartime, the ABCD line left Japan two choices: comply with the US-led demand to pull out of China or seize the oilfields in the East Indies from the Netherlands. The Japanese government deemed it unacceptable to retreat from China.[28]

Mason-Overy debate: "Flight into War" theory

In the late 1980s, the British historian Richard Overy was involved in a historical dispute with Timothy Mason that played out mostly over the pages of the Past and Present journal over the reasons for the outbreak of the war in 1939. Mason had contended that a "flight into war" had been imposed on Hitler by a structural economic crisis, which confronted Hitler with the choice of making difficult economic decisions or aggression. Overy argued against Mason's thesis by maintaining that Germany was faced with economic problems in 1939, but the extent of those problems could not explain aggression against Poland and the reasons for the outbreak of war were the choices made by the Nazi leadership.

Mason had argued that the German working-class was always against the Nazi dictatorship; that in the overheated German economy of the late 1930s, German workers could force employers to grant higher wages by leaving for another firm and so grant the desired wage increases and that such a form of political resistance forced Hitler to go to war in 1939.[29] Thus, the outbreak of the war was caused by structural economic problems, a "flight into war" imposed by a domestic crisis.[29] The key aspects of the crisis were, according to Mason, a shaky economic recovery that was threatened by a rearmament program that overwhelmed the economy and in which the regime's nationalist bluster limited its options.[29] In that way, Mason articulated a Primat der Innenpolitik ("primacy of domestic politics") view of the war's origins by the concept of social imperialism.[30] Mason's Primat der Innenpolitik thesis was in marked contrast to the Primat der Außenpolitik ("primacy of foreign politics"), which is usually used to explain the war.[29] Mason thought German foreign policy was driven by domestic political considerations, and the launch the war in 1939 was best understood as a "barbaric variant of social imperialism".[31]

Mason argued, "Nazi Germany was always bent at some time upon a major war of expansion".[32] However, Mason argued that the timing of such a war was determined by domestic political pressures, especially as relating to a failing economy, and had nothing to do with what Hitler wanted.[32] Mason believed that from 1936 to 1941, the state of the German economy, not Hitler's "will" or "intentions", was the most important determinate on German foreign policy decisions.[33]

Mason argued that the Nazi leaders were so deeply haunted by the November 1918

German Revolution that they were most unwilling to see any fall in working-class living standards for fear of provoking a repetition of the revolution.[33] Mason stated that by 1939, the "overheating" of the German economy caused by rearmament, the failure of various rearmament plans produced by the shortages of skilled workers, industrial unrest caused by the breakdown of German social policies and the sharp drop in living standards for the German working class forced Hitler into going to war at a time and a place that were not of his choosing.[34]

Mason contended that when faced with the deep socio-economic crisis, the Nazi leadership had decided to embark upon a ruthless foreign policy of "smash and grab" to seize territory in Eastern Europe that could be pitilessly plundered to support the living standards in Germany.[35] Mason described German foreign policy as driven by an opportunistic "next victim" syndrome after the Anschluss in which the "promiscuity of aggressive intentions" was nurtured by every successful foreign policy move.[36] Mason's considered the decision to sign the Molotov–Ribbentrop Pact and to attack Poland despite the risk of a war against Britain and France to be the abandonment by Hitler of his foreign policy program outlined in Mein Kampf and to have been forced on him by his need to stop a collapsing German economy by seizing territory abroad to be plundered.[34]

For Overy, the problem with Mason's thesis was that it rested on the assumption that in a way that was not shown by the records, information was passed on to Hitler about Germany's economic problems.[37] Overy argued for a difference between economic pressures induced by the problems of the Four Year Plan and economic motives to seize raw materials, industry and foreign reserves of neighbouring states as a way of accelerating the plan.[38] Overy asserted that Mason downplayed the repressive German state's capacity to deal with domestic unhappiness.[37] Finally, Overy argued that there is considerable evidence that Germany felt that it could master the economic problems of rearmament. As one civil servant put it in January 1940, "we have already mastered so many difficulties in the past, that here too, if one or other raw material became extremely scarce, ways and means will always yet be found to get out of a fix".[39]

Proximate causes

Nazi dictatorship

Adolf Hitler in Bad Godesberg, Germany, 1938

Hitler and his Nazis took full control of Germany in 1933–34 (

Machtergreifung), turning it into a dictatorship with a highly hostile outlook toward the Treaty of Versailles and Jews.[40] It solved its unemployment crisis by heavy military spending.[41]

Hitler's diplomatic tactics were to make seemingly-reasonable demands and to threaten war if they were not met. After concessions were made, he accepted them and moved onto a new demand.[42] When opponents tried to appease him, he accepted the gains that were offered and went to the next target. That aggressive strategy worked as Germany pulled out of the League of Nations (1933), rejected the Versailles Treaty, began to rearm with the Anglo-German Naval Agreement (1935), won back the Saar (1935), re-militarized the Rhineland (1936), formed an alliance ("axis") with Mussolini's Italy (1936), sent massive military aid to Franco in the Spanish Civil War (1936–39), seized Austria (1938), took over Czechoslovakia after the British and French appeasement of the Munich Agreement of 1938, formed a peace pact with Stalin's Russia in August 1939 and finally invaded Poland in September 1939.[43]

Remilitarization of the Rhineland

In violation of the Treaty of Versailles and the spirit of the

Locarno Pact and the Stresa Front, Germany remilitarized the Rhineland on March 7, 1936, by moving German troops into the part of western Germany in which according to the Versailles Treaty, they were not allowed. Neither France nor Britain was prepared fight a preventive war to stop the violation and so there were no consequences.[44]

Italian invasion of Abyssinia

Following the

Stresa Conference and even as a reaction to the Anglo-German Naval Agreement, the Italian dictator Benito Mussolini attempted to expand the Italian Empire in Africa by invading the Ethiopian Empire, also known as the Abyssinian Empire. The League of Nations declared Italy to be the aggressor and imposed sanctions on oil sales, which proved ineffective. Italy annexed Ethiopia in May 1936 and merged Ethiopia, Eritrea and Somaliland into a single colony, known as Italian East Africa. On June 30, 1936, Ethiopian Emperor Haile Selassie gave a stirring speech before the League of Nations denouncing Italy's actions and criticizing the world community for standing by. He warned, "It is us today. It will be you tomorrow". As a result of the League's condemnation of Italy, Mussolini declared the country's withdrawal from the organization.[45]

Spanish Civil War

Francisco Franco and Heinrich Himmler in Madrid, Spain, 1940

Between 1936 and 1939, Germany and Italy lent support to the

Spanish Republic, led by Manuel Azaña. Both sides experimented with new weapons and tactics. The League of Nations was never involved, and its major powers remained neutral and tried with little success to stop arms shipments into Spain. The Nationalists eventually defeated the Republicans in 1939.[46]

Spain negotiated with joining the Axis but remained neutral during World War II and did business with both sides. It also sent a volunteer unit to help the Germans against the Soviets. The Spanish Civil War was considered in the 1940s and 1950s to be a prelude to World War II, which was the case to some extent by changing it into an antifascist contest after 1941, but bore no resemblance to the war that started in 1939 and had no major role in causing it.[47][48]

Second Sino-Japanese War

In 1931, Japan took advantage of China's weakness in the

Marco Polo Bridge Incident triggered the Second Sino-Japanese War
.

The invasion was launched by the bombing of many cities such as Shanghai, Nanjing and Guangzhou. The latest, which began on 22 and 23 September 1937, called forth widespread protests culminating in a resolution by the Far Eastern Advisory Committee of the League of Nations. The Imperial Japanese Army captured the Chinese capital city of Nanjing and committed war crimes in the Nanjing Massacre. The war tied down large numbers of Chinese soldiers and so Japan set up three different Chinese puppet states to enlist some Chinese support.[49]

Anschluss

Cheering crowds greet the Nazis in Innsbruck

The

nation-state and was popular in both Austria and Germany.[50]

The National Socialist Program included the idea in one of its points: "We demand the unification of all Germans in the Greater Germany on the basis of the people's right to self-determination."

The

Rome-Berlin Axis
, Mussolini was much less interested in upholding its independence.

The Austrian government resisted as long as possible but had no outside support and finally gave in to Hitler's fiery demands. No fighting occurred, most Austrians supported the annexation and Austria was fully absorbed as part of Germany. Outside powers did nothing, and Italy had little reason for continued opposition to Germany and, if anything, was drawn in closer to the Nazis.[51][52]

Munich Agreement

The Sudetenland was a predominantly-German region in Czechoslovakia along the border with Germany. It had more than three million ethnic Germans, who comprised almost a quarter of the country's population. In the Treaty of Versailles, the region was given to the Czechoslovakia against the wishes of most of the local population. The decision to disregard its right to self-determination was based on France's intent to weaken Germany. Much of Sudetenland was industrialised.[51]

British Prime Minister Neville Chamberlain and Hitler at a meeting in Germany on 24 September 1938, and Hitler demanded the immediate annexation of Czechoslovak border areas.

Czechoslovakia had a modern army of 38 divisions, backed by a well-noted armament industry (Škoda) and military alliances with France and the Soviet Union. However, its defensive strategy against Germany was based on the mountains of the Sudetenland.

Hitler pressed for the Sudetenland's incorporation into Germany and supported German separatist groups within the region. Alleged Czechoslovak brutality and persecution under Prague helped to stir up nationalist tendencies, as did the Nazi press. After the Anschluss, all German parties except for the German Social-Democratic Party merged with the Sudeten German Party (SdP). Paramilitary activity and extremist violence peaked during the period, and the Czechoslovak government declared martial law in parts of the Sudetenland to maintain order. That only complicated the situation, especially since Slovak nationalism was rising from suspicion towards Prague and encouragement by Germany. Citing the need to protect the Germans in Czechoslovakia, Germany requested the immediate annexation of the Sudetenland.

In the Munich Agreement on September 30, 1938, the British, French, and Italian prime ministers appeased Hitler by giving him what he wanted in the hope that it would be his last demand. The powers allowed Germany to move troops into the region and incorporate it into the Reich "for the sake of peace". In exchange, Hitler gave his word that Germany would make no further territorial claims in Europe.[53] Czechoslovakia was not allowed to participate in the conference. When the French and British negotiators informed the Czechoslovak representatives about the agreement and that if Czechoslovakia would not accept it, France and Britain would consider Czechoslovakia to be responsible for war and stay neutral, Czechoslovak President Edvard Beneš capitulated and Germany took the Sudetenland unopposed.[54]

Chamberlain's policies have been the subject of intense debate for more than 70 years by academics, politicians and diplomats. The historians' assessments have ranged from condemnation for allowing Hitler's Germany to grow too strong to the judgment that Germany was so strong that it might well win a war and so the postponement of a showdown was in the country's best interests.[55]

German occupation and Slovak independence

Munich Dictate
") and March 1939

In March 1939, breaking the Munich Agreement, German troops invaded Prague, and with the Slovaks declaring independence, Czechoslovakia disappeared as a country. The entire ordeal ended the French and British policy of appeasement.

Italian invasion of Albania

After the German occupation of Czechoslovakia, Mussolini feared for Italy becoming a second-rate member of the Axis. Rome delivered

King Zog
refused to accept money in exchange for allowing a full Italian takeover and colonization of Albania.

On April 7, 1939, Italian troops invaded Albania, which was occupied after a three-day campaign with minimal resistance offered by Albanian forces.

Soviet–Japanese border war

In 1939, the Japanese attacked west from Manchuria into the Mongolian People's Republic after the 1938 Battle of Lake Khasan. They were decisively beaten by Soviet units, under General Georgy Zhukov. After the battle, the Soviet Union and Japan were at peace until 1945. Japan looked south to expand its empire, which led to conflict with the United States over the Philippines and the control of shipping lanes to the Dutch East Indies. The Soviet Union focused on its western border but left 1 million to 1.5 million troops to guard its border with Japan.

Danzig crisis

The Polish Corridor and the Free City of Danzig

After the end of Czechoslovakia proved that Germany could not be trusted, Britain and France decided on a change of strategy. They decided any further unilateral German expansion would be met by force. The natural next target for German expansion was Poland, whose

Napoleon I's crushing victory over Prussia
in 1807.

After taking power, the Nazi government made efforts to establish friendly relations with Poland, which resulted in the signing of the ten-year

Reichsautobahn Berlin-Königsberg and a change in Danzig's status in exchange for promises of territory in Poland's neighbours and a 25-year extension of the non-aggression pact. Poland refused for fear of losing its de facto access to the sea, subjugation as a German satellite state or client state and future further German demands.[56][57] In August 1939, Hitler delivered an ultimatum
to Poland on Danzig's status.

Polish alliance with the Entente