The United States Marine Corps (USMC) is a branch of the United States Armed Forces responsible for providing power projection from the sea, using the mobility of the United States Navy to deliver combined-arms task forces rapidly. It is one of seven uniformed services of the United States. In the civilian leadership structure of the United States military, the Marine Corps is a component of the United States Department of the Navy, often working closely with U.S. naval forces for training, transportation, and logistic purposes; however, in the military leadership structure the Marine Corps is a separate branch.

Captain Samuel Nicholas formed two battalions of Continental Marines on 10 November 1775 in Philadelphia as naval infantry. Since then, the mission of the Marine Corps has evolved with changing military doctrine and American foreign policy. The Marine Corps has served in every American armed conflict and attained prominence in the 20th century when its theories and practices of amphibious warfare proved prescient and ultimately formed the cornerstone of the Pacific campaign of World War II. By the mid-20th century, the Marine Corps had become the dominant theorist and practitioner of amphibious warfare. Its ability to rapidly respond on short notice to expeditionary crises gives it a strong role in the implementation and execution of American foreign policy.

The United States Marine Corps includes just under 203,000 active duty Marines (as of October 2010) and just under 40,000 reserve Marines (as of 2010). It is the smallest of the United States' armed forces in the Department of Defense (the United States Coast Guard is smaller, about one-fifth the size of the Marine Corps, but is normally under the Department of Homeland Security). The Marine Corps is nonetheless larger than the armed forces of many significant military powers; for example, it is larger than the active duty Israel Defense Forces and the entire British Army.

The US Marine Corps accounts for around six percent of the military budget of the United States. The cost per Marine is $20,000 less than the cost of a serviceman from the other services, and the entire force can be used for both hybrid and major combat operations, that is, the Marines cover the entire Three Block War.

United States Marine Corps
Active 10 November 1775 – present
Country United States of America
Branch Marine Corps
Type Amphibious and expeditionary
Role Naval Infantry
Size 202,779 active (as of October 2010)
40,000 reserve (as of 2010)
Part of Department of Defense
Department of the Navy
Headquarters Headquarters Marine Corps
Nickname The Few, The Proud
Motto Semper Fidelis
Colors Scarlet & Gold
March "Semper Fidelis"
Mascot English Bulldog
American Revolutionary War
Barbary Wars
War of 1812
Seminole Wars
Mexican–American War
American Civil War
Spanish–American War
Philippine–American War
Boxer Rebellion
Banana Wars
World War I
World War II
Korean War
Vietnam War
Gulf War
Kosovo War
Operation Enduring Freedom
Iraq War
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Presidential Unit Citation
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Joint Meritorious Unit Award
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Navy Unit Commendation
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Valorous Unit Award
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Meritorious Unit Commendation
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Croix de Guerre
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Philippine Presidential Unit Citation
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Korean Presidential Unit Citation
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Vietnam Gallantry Cross
Vietnam Civil Actions Medal
Commandant Gen James F. Amos
Assistant Commandant Gen Joseph F. Dunford, Jr.
Sergeant Major SgtMaj Carlton W. Kent
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