World War II

====Aftermath of World War I====
{{stack|[[File:Bundesarchiv Bild 102-09042, Genf, Völkerbund, Sitzungssaal.jpg|thumb|The [[League of Nations]] assembly, held in [[Geneva]], [[Switzerland]] (1930).]]}}
[[World War I]] had radically altered the political European map with the defeat of the [[Central Powers]]—including [[Austria-Hungary]], [[German Empire|Germany]], [[Kingdom of Bulgaria|Bulgaria]], and the [[Ottoman Empire]]—and the 1917 [[October Revolution|Bolshevik seizure of power]] in [[Russian Republic|Russia]], which led to the founding of the Soviet Union. Meanwhile, the victorious [[Allies of World War I]], such as France, Belgium, Italy, Romania, and Greece, gained territory, and new [[Nation state|nation-states]] were created out of the dissolution of the Austro-Hungarian, Ottoman, and Russian Empires.<ref>{{cite web |last1=Mintz |first1=Steven |title=Historical Context: The Global Effect of World War I |url=https://www.gilderlehrman.org/history-resources/teaching-resource/historical-context-global-effect-world-war-i |website=The Gilder Lehrman Institute of American History |access-date=4 March 2024 |archive-date=4 March 2024 |archive-url=https://web.archive.org/web/20240304193001/https://www.gilderlehrman.org/history-resources/teaching-resource/historical-context-global-effect-world-war-i |url-status=live }}</ref>

To prevent a future world war, the [[League of Nations]] was established in 1920 by the [[Paris Peace Conference (1919–1920)|Paris Peace Conference]]. The organisation's primary goals were to prevent armed conflict through collective security, military, and [[Washington Naval Treaty|naval disarmament]], as well as settling international disputes through peaceful negotiations and arbitration.<ref>{{cite news |last1=Gerwarth |first1=Robert |title=Paris Peace Treaties failed to create a secure, peaceful and lasting world order |url=https://www.irishtimes.com/culture/heritage/paris-peace-treaties-failed-to-create-a-secure-peaceful-and-lasting-world-order-1.3745849 |newspaper=The Irish Times |access-date=29 October 2021 |language=en |archive-date=14 August 2021 |archive-url=https://web.archive.org/web/20210814213229/https://www.irishtimes.com/culture/heritage/paris-peace-treaties-failed-to-create-a-secure-peaceful-and-lasting-world-order-1.3745849 |url-status=live }}</ref>

Despite strong pacifist sentiment [[Aftermath of World War I|after World War{{nbsp}}I]],{{sfn|Ingram|2006|pp=[{{GBurl|id=bREQibN9i-sC|p=76}} 76–78]}} [[Irredentism|irredentist]] and [[Revanchism|revanchist]] [[nationalism]] had emerged in several European states. These sentiments were especially marked in Germany because of the significant territorial, colonial, and financial losses imposed by the [[Treaty of Versailles]]. Under the treaty, Germany lost around 13 percent of its home territory and all [[German colonial empire|its overseas possessions]], while German annexation of other states was prohibited, [[World War I reparations|reparations]] were imposed, and limits were placed on the size and capability of the country's [[Reichswehr|armed forces]].{{sfn|Kantowicz|1999|p=149}}