World War II (1939-1945): This war stands as one of the most destructive and deadly conflicts in history. Millions of lives were lost, and it caused widespread destruction globally. The aggression of Nazi Germany, Japan's expansion in the Pacific, and other factors triggered this war.
World War I (1914-1918): This war was a series of conflicts among major powers. Unlike previous wars, it witnessed the use of new technologies and weapons. Estimates suggest that between 15 to 20 million people lost their lives as a result of the war.
Vietnam War (1955-1975): Taking place during the Cold War, this war between North Vietnam and South Vietnam affected many countries and people. By the end of the war, an estimated 3 to 4 million people had lost their lives.