Central and Eastern Europe
1918–1921: Wars after the Great War
November 1918 – 1921 · 3 battles
The armistices of autumn 1918 ended the First World War on the battlefronts, but not in Central and Eastern Europe. On the ruins of the Habsburg monarchy, the German Empire and the Russian Empire new states arose and fought for their borders before the Paris Peace Conference could fix them or force of arms decide them. Poles took up arms in Greater Poland, Romania marched into Transylvania and clashed with Hungary, and the reborn Poland fought a war against Bolshevik Russia that settled its eastern frontier. Disputes over ethnically mixed lands left grievances that Hitler and Stalin would exploit twenty years later.
- 13 November 1918 – 4 August 1919The Hungarian–Romanian WarFrom November 1918 Romania occupied Transylvania; in 1919 it crushed the army of the Hungarian Soviet Republic and on 4 August entered Budapest.
- 27 December 1918 – 16 February 1919The Greater Poland Uprising27 December 1918 – 16 February 1919. Poles of the Prussian Province of Posen took up arms, seized most of Greater Poland and created an army of their own.
- 14 February 1919 – 18 October 1920Key battleThe Polish–Soviet WarFrom February 1919 to October 1920 Poland fought Soviet Russia for the lands of the old Commonwealth. The Battle of Warsaw halted the revolution's march west.