World War II

===Pre-war events===

====Italian invasion of Ethiopia (1935)====
{{Main|Second Italo-Ethiopian War}}
[[File:Mussolini truppe Etiopia.jpg|thumb|[[Benito Mussolini]] inspecting troops during the [[Second Italo-Ethiopian War|Italo-Ethiopian War]], 1935]]

The [[Second Italo-Ethiopian War]] was a brief [[colonial war]] that began in October 1935 and ended in May 1936. The war began with the invasion of the [[Ethiopian Empire]] (also known as [[Etymology of Ethiopia|Abyssinia]]) by the armed forces of the [[Kingdom of Italy]] (''Regno d'Italia''), which was launched from [[Italian Somaliland]] and [[Italian Eritrea|Eritrea]].<ref>{{cite book |url=https://books.google.com/books?id=GtCL2OYsH6wC |title=Cultural Sociology of the Middle East, Asia, and Africa: An Encyclopedia |author1=Andrea L. Stanton |author2=Edward Ramsamy |author3=Peter J. Seybolt |page=308 |access-date=6 April 2014 |isbn=978-1-4129-8176-7 |year=2012 |archive-date=7 March 2023 |archive-url=https://web.archive.org/web/20230307201327/https://books.google.com/books?id=GtCL2OYsH6wC |url-status=live }}</ref> The war resulted in the [[military occupation]] of Ethiopia and its [[annexation]] into the newly created colony of [[Italian East Africa]] (''Africa Orientale Italiana'', or AOI); in addition it exposed the weakness of the [[League of Nations]] as a force to preserve peace. Both Italy and Ethiopia were member nations, [[Appeasement|but the League did little]] when the former clearly violated Article X of the League's [[Covenant of the League of Nations|Covenant]].{{sfn|Barker|1971|pp=131–132}} The United Kingdom and France supported imposing sanctions on Italy for the invasion, but the sanctions were not fully enforced and failed to end the Italian invasion.{{sfn|Shirer|1990|p=289}} Italy subsequently dropped its objections to Germany's goal of absorbing [[Federal State of Austria|Austria]].{{sfn|Kitson|2001|p=231}}

====Spanish Civil War (1936–1939)====
{{Main|Spanish Civil War}}

When civil war broke out in Spain, Hitler and Mussolini lent military support to the [[Nationalist faction (Spanish Civil War)|Nationalist rebels]], led by General [[Francisco Franco]]. Italy supported the Nationalists to a greater extent than the Nazis: Mussolini sent more than 70,000 ground troops, 6,000 aviation personnel, and 720 aircraft to Spain.{{sfn|Neulen|2000|page=25}} The Soviet Union supported the existing government of the [[Second Spanish Republic|Spanish Republic]]. More than 30,000 foreign volunteers, known as the [[International Brigades]], also fought against the Nationalists. Both Germany and the Soviet Union used this [[proxy war]] as an opportunity to test in combat their most advanced weapons and tactics. The Nationalists won the civil war in April 1939; Franco, now dictator, remained officially neutral during World War{{nbsp}}II but [[Spain during World War II|generally favoured the Axis]].{{sfn|Payne|2008|page=271}} His greatest collaboration with Germany was the sending of [[Blue Division|volunteers]] to fight on the [[Eastern Front (World War II)|Eastern Front]].{{sfn|Payne|2008|page=146}}

====Japanese invasion of China (1937)====
{{Main|Second Sino-Japanese War}}
[[File:Shanghai1937IJA ruins.jpg|thumb|[[Imperial Japanese Army]] soldiers during the [[Battle of Shanghai]], 1937]]

In July 1937, Japan captured the former Chinese imperial capital of [[Beijing|Peking]] after instigating the [[Marco Polo Bridge incident]], which culminated in the Japanese campaign to invade all of China.{{sfn|Eastman|1986|pp=547–551}} The Soviets quickly signed a [[Sino-Soviet Non-Aggression Pact|non-aggression pact with China]] to lend [[materiel]] support, effectively ending China's prior [[China–Germany relations (1912–1949)|cooperation with Germany]]. From September to November, the Japanese attacked [[Battle of Taiyuan|Taiyuan]], engaged the [[National Revolutionary Army|Kuomintang Army]] [[Battle of Xinkou|around Xinkou]],<ref name="Hsu & Chang 1971 221">{{Harvnb|Hsu|Chang|1971|pp=195–200}}.</ref> and fought [[Chinese Communist Party|Communist forces]] [[Battle of Pingxingguan|in Pingxingguan]].<ref name=Tucker2009>{{Cite book|url=https://books.google.com/books?id=h5_tSnygvbIC&pg=PA1873|title=A Global Chronology of Conflict: From the Ancient World to the Modern Middle East [6 volumes]: From the Ancient World to the Modern Middle East|first=Spencer C.|last=Tucker|year=2009|publisher=ABC-CLIO|access-date=27 August 2017|via=Google Books|isbn=978-1-85109-672-5|archive-date=7 March 2023|archive-url=https://web.archive.org/web/20230307201303/https://books.google.com/books?id=h5_tSnygvbIC&pg=PA1873|url-status=live}}</ref><ref name=yang>Yang Kuisong, "On the reconstruction of the facts of the Battle of Pingxingguan"</ref> [[Generalissimo]] [[Chiang Kai-shek]] deployed his [[List of German-trained divisions of the National Revolutionary Army|best army]] to [[Battle of Shanghai|defend Shanghai]], but after three months of fighting, Shanghai fell. The Japanese continued to push Chinese forces back, [[Battle of Nanking|capturing the capital Nanking]] in December 1937. After the fall of Nanking, tens or hundreds of thousands of Chinese civilians and disarmed combatants were [[Nanjing Massacre|murdered by the Japanese]].<ref>Levene, Mark and Roberts, Penny. ''The Massacre in History''. 1999, pp. 223–224</ref><ref name=tot>Totten, Samuel. ''Dictionary of Genocide''. 2008, 298–299.</ref>

In March 1938, Nationalist Chinese forces won their [[Battle of Taierzhuang|first major victory at Taierzhuang]], but then the city of [[Xuzhou]] [[Battle of Xuzhou|was taken by the Japanese]] in May.{{sfn|Hsu|Chang|1971|pp=221–230}} In June 1938, Chinese forces stalled the Japanese advance by [[1938 Yellow River flood|flooding the Yellow River]]; this manoeuvre bought time for the Chinese to prepare their defences at [[Wuhan]], but the [[Battle of Wuhan|city was taken]] by October.{{sfn|Eastman|1986|p=566}} Japanese military victories did not bring about the collapse of Chinese resistance that Japan had hoped to achieve; instead, the Chinese government relocated inland to [[Chongqing]] and continued the war.{{sfn|Taylor|2009|pp=150–152}}{{sfn|Sella|1983|pp=651–687}}

====Soviet–Japanese border conflicts====
{{Main|Soviet–Japanese border conflicts}}

In the mid-to-late 1930s, Japanese forces in [[Manchukuo]] had sporadic border clashes with the Soviet Union and [[Mongolian People's Republic|Mongolia]]. The Japanese doctrine of [[Hokushin-ron]], which emphasised Japan's expansion northward, was favoured by the Imperial Army during this time. This policy would prove difficult to maintain in light of the Japanese defeat at [[Battles of Khalkhin Gol|Khalkin Gol]] in 1939, the ongoing Second Sino-Japanese War{{sfn|Beevor|2012|p=342}} and ally Nazi Germany pursuing neutrality with the Soviets. Japan and the Soviet Union eventually signed a [[Soviet–Japanese Neutrality Pact|Neutrality Pact]] in April 1941, and Japan adopted the doctrine of [[Nanshin-ron]], promoted by the Navy, which took its focus southward and eventually led to war with the United States and the Western Allies.<ref>{{cite magazine |author=Goldman, Stuart D. |date=28 August 2012 |title=The Forgotten Soviet-Japanese War of 1939 |access-date=26 June 2015 |magazine=The Diplomat |url=https://thediplomat.com/2012/08/the-forgotten-soviet-japanese-war-of-1939/ |archive-url=https://web.archive.org/web/20150629092821/https://thediplomat.com/2012/08/the-forgotten-soviet-japanese-war-of-1939/ |archive-date=29 June 2015 |url-status=live}}</ref><ref>{{cite web |author=Timothy Neeno |access-date=26 June 2015 |title=Nomonhan: The Second Russo-Japanese War |publisher=MilitaryHistoryOnline.com |url=https://www.militaryhistoryonline.com/20thcentury/articles/nomonhan.aspx |archive-url=https://web.archive.org/web/20051124070956/https://www.militaryhistoryonline.com/20thcentury/articles/nomonhan.aspx |archive-date=24 November 2005 |url-status=live}}</ref>

====European occupations and agreements====
[[File:Bundesarchiv Bild 183-R69173, Münchener Abkommen, Staatschefs.jpg|thumb|left|[[Neville Chamberlain|Chamberlain]], [[Édouard Daladier|Daladier]], [[Adolf Hitler|Hitler]], [[Benito Mussolini|Mussolini]], and [[Galeazzo Ciano|Ciano]] pictured just before signing the [[Munich Agreement]], 29 September 1938]]

In Europe, Germany and Italy were becoming more aggressive. In March 1938, Germany [[Anschluss|annexed Austria]], again provoking [[appeasement|little response]] from other European powers.{{sfn|Collier|Pedley|2000|p=144}} Encouraged, Hitler began pressing German claims on the [[Sudetenland]], an area of [[Czechoslovakia]] with a predominantly [[Germans|ethnic German]] population. Soon the United Kingdom and France followed the appeasement policy of British Prime Minister [[Neville Chamberlain]] and conceded this territory to Germany in the [[Munich Agreement]], which was made against the wishes of the Czechoslovak government, in exchange for a promise of no further territorial demands.{{sfn|Kershaw|2001|pp=121–122}} Soon afterwards, Germany and Italy forced Czechoslovakia to [[First Vienna Award|cede additional territory]] to Hungary, and Poland annexed the [[Trans-Olza]] region of Czechoslovakia.{{sfn|Kershaw|2001|p=157}}

Although all of Germany's stated demands had been satisfied by the agreement, privately Hitler was furious that British interference had prevented him from seizing all of Czechoslovakia in one operation. In subsequent speeches Hitler attacked British and Jewish "war-mongers" and in January 1939 [[Plan Z|secretly ordered a major build-up of the German navy]] to challenge British naval supremacy. In March 1939, [[Occupation of Czechoslovakia (1938–1945)|Germany invaded the remainder of Czechoslovakia]] and subsequently split it into the German [[Protectorate of Bohemia and Moravia]] and a pro-German [[client state]], the [[Slovak Republic (1939–1945)|Slovak Republic]].{{sfn|Davies|2006|loc=pp. 143–44 (2008 ed.)}} Hitler also delivered an [[1939 German ultimatum to Lithuania|ultimatum to Lithuania]] on 20 March 1939, forcing the concession of the [[Klaipėda Region]], formerly the German ''Memelland''.{{sfn|Shirer|1990|pp=461–462}}

[[File:Bundesarchiv Bild 183-H27337, Moskau, Stalin und Ribbentrop im Kreml.jpg|right|thumb|upright|German Foreign Minister [[Joachim von Ribbentrop]] (right) and the Soviet leader [[Joseph Stalin]], after signing the [[Molotov–Ribbentrop Pact]], 23 August 1939]]
Greatly alarmed and with Hitler making further demands on the [[Free City of Danzig]], the United Kingdom and France [[Anglo-Polish alliance#British assurance to Poland|guaranteed their support for Polish independence]]; when [[Italian invasion of Albania|Italy conquered Albania]] in April 1939, the same guarantee was extended to the [[Kingdom of Romania|Kingdoms of Romania]] and [[Kingdom of Greece|Greece]].{{sfn|Lowe|Marzari|2002|p=330}} Shortly after the [[Franco-Polish alliance|Franco]]-[[Anglo-Polish alliance|British]] pledge to Poland, Germany and Italy formalised their own alliance with the [[Pact of Steel]].{{sfn|Dear|Foot|2001|p=234}} Hitler accused the United Kingdom and Poland of trying to "encircle" Germany and renounced the [[Anglo-German Naval Agreement]] and the [[German–Polish declaration of non-aggression]].{{sfn|Shirer|1990|p=471}}

The situation became a crisis in late August as German troops continued to mobilise against the Polish border. On 23 August the Soviet Union signed [[Molotov–Ribbentrop Pact|a non-aggression pact]] with Germany,{{sfn|Shore|2003|p=108}} after tripartite negotiations for a military alliance between France, the United Kingdom, and Soviet Union had stalled.<ref>{{Cite journal |last1=Watson |first1=Derek |year=2000 |title=Molotov's Apprenticeship in Foreign Policy: The Triple Alliance Negotiations in 1939 |journal=Europe-Asia Studies |volume=52 |issue=4 |pages=695–722 |doi=10.1080/713663077 |jstor=153322 |s2cid=144385167}}</ref> This pact had a secret protocol that defined German and Soviet "spheres of influence" (western [[Second Polish Republic|Poland]] and Lithuania for Germany; [[Territories of Poland annexed by the Soviet Union|eastern Poland]], Finland, [[Estonia]], [[Latvia]] and [[Bessarabia]] for the Soviet Union), and raised the question of continuing Polish independence.{{sfn|Dear|Foot|2001|p=608}} The pact neutralised the possibility of Soviet opposition to a campaign against Poland and assured that Germany would not have to face the prospect of a two-front war, as it had in World War{{nbsp}}I. Immediately afterwards, Hitler ordered the attack to proceed on 26 August, but upon hearing that the United Kingdom had concluded a formal mutual assistance pact with Poland and that Italy would maintain neutrality, he decided to delay it.<ref>{{cite web|url=https://www.ibiblio.org/hyperwar/USA/DAP-Poland/Campaign-II.html#chapter5|title=The German Campaign In Poland (1939)|access-date=29 October 2014|archive-url=https://web.archive.org/web/20140524013551/https://www.ibiblio.org/hyperwar/USA/DAP-Poland/Campaign-II.html#chapter5|archive-date=24 May 2014|url-status=live}}</ref>

In response to British requests for direct negotiations to avoid war, Germany made demands on Poland, which served as a pretext to worsen relations.<ref name=ww2db_com>{{cite web |url=https://ww2db.com/battle_spec.php?battle_id=162 |title=The Danzig Crisis |website=ww2db.com |access-date=29 April 2016 |archive-url=https://web.archive.org/web/20160505010109/https://ww2db.com/battle_spec.php?battle_id=162 |archive-date=5 May 2016 |url-status=live}}</ref> On 29 August, Hitler demanded that a Polish [[plenipotentiary]] immediately travel to Berlin to negotiate the handover of [[Gdańsk|Danzig]], and to allow a [[referendum|plebiscite]] in the [[Polish Corridor]] in which the German minority would vote on secession.<ref name=ww2db_com /> The Poles refused to comply with the German demands, and on the night of 30–31 August in a confrontational meeting with the British ambassador [[Nevile Henderson]], Ribbentrop declared that Germany considered its claims rejected.<ref name=ibiblio1939>{{cite web |title=Major international events of 1939, with explanation |url=https://www.ibiblio.org/pha/events/1939.html |publisher=Ibiblio.org |access-date=9 May 2013 |archive-url=https://web.archive.org/web/20130310103815/https://www.ibiblio.org/pha/events/1939.html |archive-date=10 March 2013 |url-status=live}}</ref>