Marine, a soldier who normally serves as part of a naval force. Marines are especially trained for combined land and sea (amphibious) warfare. They serve as landing and boarding parties and on shipboard man guns and enforce discipline. They are separately organized, but form part of the navy in which they serve.
Marines originated in sailing-ship days to provide fighting men freed from the duties of ship operation. A “maritime regiment of foot” was organized for the British navy in 1664. The name became Royal Marines in 1802. The Royal Netherlands korps mariniers dates from 1665. Marines first served the United States in 1775.