- German Empire: The German Empire was defeated in World War I and its territory was divided up among the Allied Powers. Germany lost Alsace-Lorraine to France, Eupen-Malmédy to Belgium, North Schleswig to Denmark, and West Prussia, Posen, and Upper Silesia to Poland. The German colonial empire was also divided up among the Allied Powers.
- Austro-Hungarian Empire: The Austro-Hungarian Empire was defeated in World War I and its territory was divided up among the Allied Powers. Austria lost South Tyrol to Italy, Bukovina to Romania, Galicia and Lodomeria to Poland, and Dalmatia to Yugoslavia. Hungary lost Transylvania to Romania, Slovakia to Czechoslovakia, and Croatia-Slavonia to Yugoslavia.
- Russian Empire: The Russian Empire was defeated in World War I and its territory was divided up among the Allied Powers and the newly independent states of Finland, Estonia, Latvia, Lithuania, and Poland. Russia lost Finland, Estonia, Latvia, Lithuania, Poland, and Bessarabia.
- Ottoman Empire: The Ottoman Empire was defeated in World War I and its territory was divided up among the Allied Powers. The Ottoman Empire lost the Arabian Peninsula, Syria, Lebanon, Palestine, Transjordan, Iraq, and Cyprus.
These four empires were some of the most powerful in the world before World War I, but they were all defeated and dismantled as a result of the war. Their collapse marked the end of an era and the beginning of a new order in Europe and the world.