Short-term effects of World War I (1914–1918) included the collapse of four empires, the enormous human and material losses caused by modern warfare, and the rise of non-democratic political systems.
World War I led to the collapse of Romanov Russia, Hapsburg Austria, Ottoman Turkey, and the German Empire. Defeated in war, the ruling dynasties of these four nations collapsed, and chaos ensued.
The carnage of World War I was much worse than that of any previous conflict in human history. Millions of soldiers were killed or maimed, and these men would have been among the leaders of their nations had they lived. The use of tanks and machine-guns had made war far more deadly. The severity of the losses made Anglo-French leaders overly timid during the interregnum between World War I and World War II. And the war cost was at least three hundred billion dollars in both direct and indirect expenses.
Political extremism appeared during and immediately after the war in Russia, Hungary, and Italy. Lenin established the Soviet Union, a Communist dictatorship. Bela Kun tried to do the same in Hungary. The Italian government was weak after the war, and this enabled Benito Mussolini to establish Fascism in Italy.
The mos -important long-term effect of the war was that it contributed to the rise of Adolph Hitler in Germany. Germany was forced to sign the Treaty of Versailles after World War I, and this discredited that country's postwar government—the Weimar Republic. Versailles, Germany's economic problems, and Hitler's shrewdness led to the creation of Nazi Germany, the Holocaust, and World War II.