The United States Marine Corps (USMC), also referred to as the United States Marines, is a branch of the United States Armed Forces responsible for conducting expeditionary and amphibious operations with the United States Navy as well as the Army and Air Force. The U.S. Marine Corps is one of the four armed service branches in the U.S. Department of Defense (DoD) and one of the seven uniformed services of the United States.
The Marine Corps has been a component of the U.S. Department of the Navy since 30 June 1834, working closely with naval forces. The USMC operates installations on land and aboard sea-going amphibious warfare ships around the world. Additionally, several of the Marines' tactical aviation squadrons, primarily Marine Fighter Attack squadrons, are also embedded in Navy carrier air wings and operate from the aircraft carriers.
The history of the Marine Corps began when two battalions of Continental Marines were formed on 10 November 1775 in Philadelphia as a service branch of infantry troops capable of fighting both at sea and on shore. In the Pacific theater of World War II the Corps took the lead in a massive campaign of amphibious warfare, advancing from island to island. As of 2017, the USMC has around 186,000 active duty members and some 38,500 personnel in reserve. It is the smallest U.S. military service within the DoD.