Dissolution of Austria-Hungary: Austria becomes a republic. After the proclamation, a coup attempt by the communist Red Guard is defeated by the social-democratic Volkswehr.

The dissolution of Austria-Hungary was a major political event that occurred as a result of the growth of internal social contradictions and the separation of different parts of Austria-Hungary. The more immediate reasons for the collapse of the state were World War I, the worsening food crisis since late 1917, general starvation in Cisleithania during the winter of 1917–1918, the demands of Austria-Hungary's military alliance with the German Empire and its de facto subservience to the German High Command, and its conclusion of the Bread Peace of 9 February 1918 with Ukraine, resulting in uncontrollable civil unrest and nationalist secessionism. The Austro-Hungarian Empire had additionally been weakened over time by a widening gap between Hungarian and Austrian interests. Furthermore, a history of chronic overcommitment rooted in the 1815 Congress of Vienna in which Metternich pledged Austria to fulfill a role that necessitated unwavering Austrian strength and resulted in overextension. Upon this weakened foundation, additional stressors during World War I catalyzed the collapse of the empire. The 1917 October Revolution and the Wilsonian peace pronouncements from January 1918 onward encouraged socialism on the one hand, and nationalism on the other, or alternatively a combination of both tendencies, among all peoples of the Habsburg monarchy.