Wikipedia:
The Great War, was a global war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918. More than 70 million military personnel, including 60 million Europeans, were mobilised in one of the largest wars in history.[5][6] Over 9 million combatants and 7 million civilians died as a result of the war, a casualty rate exacerbated by the belligerents' technological and industrial sophistication, and tactical stalemate. It was one of the deadliest conflicts in history, and paved the way for major political changes, including revolutions in many of the nations involved.[7]
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The Russian government collapsed in March 1917, and a subsequent revolution in November brought the Russians to terms with the Central Powers via the Treaty of Brest Litovsk, which constituted a massive German victory. After a stunning Spring 1918 German offensive along the Western Front, the Allies rallied and drove back the Germans in a series of successful offensives. On 4 November 1918, the Austro-Hungarian empire agreed to an armistice, and Germany, which had its own trouble with revolutionaries, agreed to an armistice on 11 November 1918, ending the war in victory for the Allies.
By the end of the war, the German Empire, Russian Empire, Austro-Hungarian Empire and the Ottoman Empire had ceased to exist. National borders were redrawn, with several independent nations restored or created, and Germany's colonies were parceled out among the winners. During the Paris Peace Conference of 1919, the Big Four (Britain, France, the United States and Italy) imposed their terms in a series of treaties. The League of Nations was formed with the aim of preventing any repetition of such a conflict. This, however, failed with economic depression, renewed European nationalism, weakened member states, and the German feeling of humiliation contributing to the rise of Nazism.