Tensions Build between World Powers (3:23)

Austria-Hungary Alliance vs. Serbia (2:29)

Four Steps to War (1:49)

Credits: The Origins of World War I (0:19)

Treaty of Versailles (2:38)

League of Nations (3:52)

Credits: The Treaty of Versailles and the League of Nations (0:19)

Rise of Germany: 1933-1939 (2:32)

Hitler's War: Start of WWII (3:38)

Credits: Conflict in the Modern World: The Origins of World War I and World War II (0:26).