The war's end triggered the abdication of various monarchies and the collapse of five of the last modern empires of Russia, Germany, China, Ottoman Turkey and Austria-Hungary, with the latter splintered into Austria, Hungary, southern Poland (who acquired most of their land in a war with Soviet Russia), Czechoslovakia and Yugoslavia, as well as the unification of Romania with Transylvania and Moldavia. However, each of these states (with the possible exception of Yugoslavia) had large German and Hungarian minorities, creating some unexpected problems that would be brought to light in the next two decades. (See Dissolution of Austro-Hungarian Empire: Successor States for better description of composition of names of successor countries/states following the splinter.)
Armenian Genocide during and just after World War I. It was characterised by the use of massacres and deportations involving forced marches under conditions designed to lead to the death of the deportees, with the total number of Armenian deaths generally held to have been between one and one-and-a-half million.
Mexican Revolution (1910–1920) Francisco I. Madero proclaims the elections of 1910 null and void, and calls for an armed revolution at 6 p.m. against the illegitimate presidency/dictatorship of Porfirio Díaz. The revolution lead to the ouster of Porfirio Díaz (who ruled from 1876 to 1880 and since 1884) six months later. The Revolution progressively becomes a civil war with multiple factions and phases, culminating with the Mexican Constitution of 1917, but combat would persist for three more years.