The 20th century witnessed several major events and conflicts that shaped the course of history. World War I, which lasted from 1914 to 1918, resulted in devastating loss of life and territory. The Great Depression in the 1930s caused widespread economic hardship, leading to social unrest and political upheaval. World War II, from 1939 to 1945, was even more destructive than its predecessor, engulfing the world in a global conflict. The Cold War between the Soviet Union and the United States defined much of the post-war period, characterized by political tension and the threat of nuclear war. These major events and conflicts left a lasting impact on global politics, society, and culture.