United States Marine Corps | 245,944 followers on LinkedIn. Official page of the United States Marine Corps - our nation's naval expeditionary force-in-readiness. | The United States Marine Corps (USMC) is a branch of the United States Armed Forces responsible for providing power projection, using the mobility of the United States Navy, by Congressional mandate, to deliver rapidly, combined-arms task forces on land, at sea, and in the air. The U.S. Marine Corps is one of the four armed service branches in the U.S.