World History/Effects of the First World War
The First World War left Europe in ruins. By the Treaty of Versailles, Germany, taking the blame for the war, was forced to pay massive reparations to the victorious Allies and lost lands to France and a restored Poland. The Austro-Hungarian Empire collapsed, with Czechoslovakia seceding, and other territories going to Poland, Serbia (now Yugoslavia), Italy, and Romania. These changes were made permanent by the Treaty of Saint-Germain, which also gave Yugoslavia the Austrian Adriatic Fleet. Bulgaria ceded small strips of territory to Romania, Yugoslavia, and Greece.
Most devastating, though, was a massive influenza outbreak that started on the front lines and spread throughout the world, carried by soldiers returning from the war. This outbreak killed more people in more countries than the war itself.