<P> The United States Marine Corps (USMC), also known as the United States Marines, is a branch of the United States Armed Forces responsible for conducting amphibious operations with the United States Navy . 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 . </P> <P> 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 . </P> <P> 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 on both at sea and on shore . By the mid-20th century, the U.S. Marine Corps had become a major theorist of amphibious warfare, which were utilized in the Pacific theater of World War II . As of 2016, the USMC has around 182,000 active duty members and some 38,500 reserve Marines . It is the smallest U.S. military service within the DoD . </P> <P> As outlined in 10 U.S.C. § 5063 and as originally introduced under the National Security Act of 1947, three primary areas of responsibility for the Marine Corps are: </P>

When did the marines become their own branch