Citizenship test guide
Immigrants who served in American wars: the numbers, from the Civil War to today
Immigrants have served the United States in its wars since the beginning. See how many served and became citizens in each war on the citizenship civics test, and learn how military service can lead to citizenship.
Start practicing →Immigrants who served
Immigrants have served in the United States military since the founding of the country. Some were already living here, some came as young soldiers from other countries, and some were not yet citizens when they put on a uniform. Many were honored for bravery, and more than 700 immigrants have received the Medal of Honor, the nation's highest award for valor.
This page gives the numbers: how many service members became citizens, and how many immigrants served in the wars where we found reliable counts. Where there is no exact count, we say so. It also explains how military service can lead to citizenship. The citizenship civics test asks which war won independence, which war was fought between the North and the South, and why the country entered World War I, World War II and the wars in Korea, Vietnam and the Persian Gulf.
- 1861 to 1865The Civil War
- 1917 to 1918World War I
- 1941 to 1945World War II
- 1950 to 1953The Korean War
- 1955 to 1975The Vietnam War
- 1990 to todayThe Persian Gulf, Iraq and Afghanistan
We give numbers only where we found a reliable source. To meet notable immigrants from many fields, read the history of immigration to the United States.
The big picture
- Since the end of World War I, about 818,000 service members who were not citizens have become citizens through military service (817,991 from fiscal year 1918 through 2024). The numbers rose in wartime. Congressional Research Service report R48163 (May 2026)
- World War I produced the most in a single year: more than 128,000 in fiscal year 1919, after a 1918 law made naturalization faster for service members. Congressional Research Service report R48163 (May 2026)
- Congress and presidents have named certain periods of hostilities for faster naturalization: World War I (April 6, 1917 to November 11, 1918), World War II (September 1, 1939 to December 31, 1946), the Korean War (June 25, 1950 to July 1, 1955), the Vietnam War (February 28, 1961 to October 15, 1978), the Persian Gulf War (August 2, 1990 to April 11, 1991) and the War on Terrorism (September 11, 2001 to today). Congressional Research Service report R48163 (May 2026)
- Today, nearly 50,000 service members are not US citizens (Department of Defense data, February 2026). About 125,440 veterans who live in the United States and served on active duty are still not citizens (a Congressional Research Service estimate from the 2024 American Community Survey). Congressional Research Service report R48163 (May 2026)
1861 to 1865
The Civil War
The war between the North and the South ended slavery. Almost one Union soldier in four was born in another country.
- The National Archives says almost one Union soldier in four was born in another country. National Archives: Jewish soldiers in the Civil War, the Union army
- The Library of Congress estimates that up to 216,000 German-born soldiers and about 150,000 Irish-born soldiers served in the Union army. The Union's XI Corps was largely German American. Library of Congress: minorities in the Civil War, a resource guide
- The Irish Brigade, made up of regiments from several states, fought at Antietam and is remembered there by a monument. National Park Service: Irish Brigade monument at Antietam
- In 1862 Congress passed a law that let immigrants who enlisted in the military, and immigrant veterans, become citizens with one year of residence. Congressional Research Service report R48163 (May 2026)
1917 to 1918
World War I
More than 18 percent of the US Army in World War I was born in another country, and almost one in five draftees was born overseas.
- The 77th Division, nicknamed the Melting Pot Division, drew most of its soldiers from New York City, and its patch showed the Statue of Liberty. Congress passed a law for faster naturalization of foreign-born service members, and more than 300,000 immigrant soldiers became citizens of the country they served. USCIS: The Immigrant Army, immigrant service members in World War I
- The Army offered English and citizenship classes in training camps for soldiers who did not yet speak English. USCIS: The Immigrant Army
- Thirteen immigrants received the Medal of Honor in World War I. USCIS: The Immigrant Army, immigrant service members in World War I
- A 1918 law let service members become citizens without the five years of residence, the English requirement or the civics exam that were normally required. Congressional Research Service report R48163 (May 2026)
On the civics test:
1941 to 1945
World War II
More than 100,000 service members became citizens during the war, including thousands who were naturalized overseas.
- The Second War Powers Act of 1942 allowed faster naturalization for service members, and the first naturalization ceremonies overseas were held. USCIS counts 110,678 service members naturalized between March 1942 and June 1945, including 13,587 abroad. USCIS: military naturalization during World War II
- Congress repealed the Chinese Exclusion Act in 1943. The Army says an estimated 40 percent of Chinese American soldiers were not born in the United States, and many became citizens through their service. US Army Center of Military History: Chinese Americans in World War II
- Filipino soldiers served in the 1st Filipino Regiment and the 2nd Filipino Battalion of the United States Army. US Army Center of Military History: the 1st Filipino Regiment
- The Second War Powers Act of 1942 gave service members in World War II the same kind of exemptions. Congressional Research Service report R48163 (May 2026)
On the civics test:
1950 to 1953
The Korean War
The United States sent troops to help South Korea after North Korea invaded. Immigrants served, and the law again made citizenship faster for non-citizens in uniform.
- Congress passed special legislation for service during the Korean hostilities that let non-citizens who served apply for citizenship faster than usual, and the period named for this ran from June 25, 1950 to July 1, 1955. Congressional Research Service report R48163 (May 2026)
- The Congressional Research Service shows military naturalizations rising during the Korean War years, but it does not give a total for the war, and we have not found a source that does. We do not have exact numbers. Congressional Research Service report R48163 (May 2026)
- An estimated 2,561 veterans who live in the United States today and served in the Korean War or World War II are still not citizens. Congressional Research Service report R48163 (May 2026)
On the civics test:
1955 to 1975
The Vietnam War
The United States sent troops to try to stop the spread of communism in Southeast Asia. Immigrants served in this war too.
- Special legislation again allowed expedited naturalization for non-citizens who served during the Vietnam hostilities. The named period ran from February 28, 1961 to October 15, 1978, when an executive order ended the faster process. Congressional Research Service report R48163 (May 2026)
- Military naturalizations rose in the Vietnam years, according to the Congressional Research Service, but the report gives no total for the war, and we have not found a source that does. We do not have exact numbers. Congressional Research Service report R48163 (May 2026)
- An estimated 21,753 veterans who live in the United States today and served in the Vietnam era are not citizens, about 17 percent of all veterans who are not citizens. Congressional Research Service report R48163 (May 2026)
On the civics test:
1990 to today
The Persian Gulf, Iraq and Afghanistan
The United States fought the Persian Gulf War in 1991. After the attacks of September 11, 2001, a long period of military operations began, including the wars in Iraq and Afghanistan, and a 2002 executive order let service members who are not citizens apply for citizenship sooner.
- The Persian Gulf War period for faster naturalization ran from August 2, 1990 to April 11, 1991, and an executive order in 1994 allowed those who served in it to apply. Congressional Research Service report R48163 (May 2026)
- On July 3, 2002, an executive order named the time since September 11, 2001 a period of armed conflict, so service members who are not citizens can apply for naturalization without waiting for a set length of service. Congressional Research Service report R48163 (May 2026)
- The Congressional Research Service counts about 148,000 service members naturalized during the War on Terrorism (through fiscal year 2024). USCIS reports more than 187,000 from 2002 to 2024, including more than 16,290 in fiscal year 2024. The totals differ by source and by how the period is counted. Congressional Research Service report R48163 (May 2026)
- An estimated 57,778 veterans who served in the War on Terrorism and 38,481 who served in the Gulf War era are not citizens today (people who served in both periods are counted twice). Congressional Research Service report R48163 (May 2026)
On the civics test:
The American Revolution
Immigrants also served in the American Revolution, and they received honors for bravery in it. We did not find a reliable count of how many immigrants fought in that war, so we do not give one. Across all of America's wars, USCIS says more than 700 immigrants have received the Medal of Honor, the nation's highest award for valor. USCIS: immigrant Medal of Honor recipients
How military service can lead to citizenship
Serving is never required to become a citizen. The Oath of Allegiance that new citizens take includes a promise to bear arms or perform noncombatant service for the United States when the law requires it. People with a religious or conscientious objection can ask for a change to those words.
Immigrants who serve honorably can apply sooner and without a fee. Under section 328 of the Immigration and Nationality Act, a service member who served honorably for at least one year may apply for naturalization. Section 329 covers service during designated periods of hostilities. If a service member dies because of service, the family can ask for posthumous citizenship, an honorary status. The rules change, so check the USCIS page before you apply.
- USCIS: naturalization through military service
- USCIS: Oath of Allegiance to the United States of America
- USCIS Policy Manual: posthumous citizenship
Checked in October 2026. This page is general education and is not legal advice. If something here is out of date, use Report a problem in the footer.
Citizenship test questions about these wars
Each question links to the answers USCIS accepts. Then say your answers out loud, because the real test is spoken.
- Name two promises that new citizens make in the Oath of Allegiance.
- What war did the Americans fight to win independence from Britain?
- Name the U.S. war between the North and the South.
- Name one war fought by the United States in the 1900s.
- Why did the United States enter World War I?
- Why did the United States enter World War II?
- Why did the United States enter the Korean War?
- Why did the United States enter the Vietnam War?
- Why did the United States enter the Persian Gulf War?
See also the history of the American flag, the immigration resources and laws, or all 128 questions.
Questions people ask
Can immigrants serve in the US military?
Yes. Lawful permanent residents (green card holders) can enlist, and immigrants have served in every major American war. Rules about who may enlist change, so check with a recruiter or the Department of Defense.
How many immigrants have received the Medal of Honor?
USCIS says more than 700 immigrants have received the Medal of Honor, the nation's highest award for valor, since the first medals were awarded during the Civil War.
Does military service make it faster to become a citizen?
It can. Under section 328 of the Immigration and Nationality Act, a service member who served honorably for at least one year may apply for naturalization, and service during certain periods of hostilities can qualify under section 329, without fees. Check the USCIS page for the current rules.
Do I have to serve in the military to become a citizen?
No. The Oath of Allegiance includes a promise to bear arms or perform noncombatant service when the law requires it. People with a religious or conscientious objection can ask for a change to those words.
Which wars are on the citizenship test?
The civics test asks about the American Revolution, the Civil War, and wars of the 1800s and 1900s, including why the United States entered World War I, World War II, and the wars in Korea, Vietnam and the Persian Gulf. This page follows those wars in order.
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