Name one war fought by the United States in the 1900s.

Why This Matters

The United States fought in several major wars during the 1900s. Each of these conflicts changed the country in lasting ways. They affected the economy, the role of government, and how America interacted with other nations around the world. Understanding these wars helps you see why the U.S. became a global leader.

World War I (1917-1918) was the first time the United States sent large numbers of troops to fight in Europe. World War II (1941-1945) was the largest and most destructive war in history, and the U.S. played a major role in defeating the Axis powers. The Korean War (1950-1953) and the Vietnam War (1955-1975) were both connected to the effort to stop the spread of communism during the Cold War. The Persian Gulf War (1991) was fought to free Kuwait after Iraq invaded it.

These wars shaped the country you are joining as a new citizen. They influenced immigration policy, civil rights progress, and the growth of the U.S. military. Many American families have personal connections to one or more of these conflicts, so this is a topic that matters deeply to people across the nation.

Key Facts

• The U.S. fought in five major wars during the 1900s: World War I, World War II, the Korean War, the Vietnam War, and the Persian Gulf War
• You only need to name one war to answer this question correctly
• World War II had the most American casualties of any 20th-century war, with over 400,000 deaths
• The Korean War is sometimes called "The Forgotten War" because it received less public attention than World War II or Vietnam
• The Persian Gulf War lasted only about six weeks of active combat

Common Mistakes

• Naming the Civil War, which was fought in the 1800s (1861-1865), not the 1900s
• Naming the War of 1812 or the Revolutionary War, which were fought much earlier
• Saying "Iraq War" or "War on Terror", while these are real conflicts, the official USCIS answer list for this question focuses on the five wars listed above

Study Tip

Remember that the 1900s means the twentieth century. A simple way to memorize the five wars is to think of them in order: WWI, WWII, Korea, Vietnam, Gulf. You only need to name one, so pick the war you know best and practice saying its full name out loud.