USCIS 128:100. Name one war fought by the United States in the 1900s.

OpenAI. (2026). Name one war fought by the United States in the 1900s.   [AI-generated infographic]. OpenAI.  Edited by Jennifer Gagliardi

The 1900s were a time of many wars around the world. During this century, the United States became more involved in world events and fought in several wars overseas. These wars changed American society, the economy, technology, and the role of the United States in the world.

One important war was World War I from 1914 to 1918. At first, the United States stayed neutral and did not join the war. Later, Germany attacked ships connected to the United States, so the U.S. entered the war in 1917. The United States fought with the Allied countries, including Great Britain and France. American soldiers helped defeat Germany, and the war ended in 1918.

About twenty years later, the world entered another war called World War II from 1939 to 1945. Before the United States joined the war, President Franklin D. Roosevelt gave the Four Freedoms Speech in January 6, 1941. He said that all people should have:

• freedom of speech,
• freedom of religion,
• freedom from want,
• and freedom from fear.

These ideas became important goals during the war.

The United States entered World War II after Japan attacked Pearl Harbor, Hawaii, on December 7, 1941. The United States fought against Germany, Italy, and Japan.

During World War II, millions of Americans served in the military or worked in factories to help the war effort. Many women started working.  The war ended in Europe in May 1945 and in Asia in September 1945 after the United States dropped atomic bombs on Hiroshima and Nagasaki in Japan.

After World War II, the United States and communist countries had many disagreements during a time called the Cold War. One war during this time was the Korean War from 1950 to 1953. North Korea invaded South Korea, and the United States helped defend South Korea. The war ended with an armistice, but Korea is still divided today.

Another Cold War conflict was the Vietnam War, which lasted from the 1950s until 1975. The United States supported South Vietnam against communist North Vietnam. Many Americans disagreed about the war, and large anti-war protests took place across the country. The war had a major impact on American politics and society.

Later, the United States fought in the Persian Gulf War in 1990–1991. The war began after Iraq invaded Kuwait. The United States and its allies forced Iraqi troops to leave Kuwait.

These wars changed the United States in many ways. They affected politics, civil rights, immigration, technology, and the economy. Many Americans served in the military, and many families were affected by war.