marine
marine, member of a military force especially recruited, trained, and organized for service at sea and in land operations incident to naval campaigns.
The use of marines goes far back in history. The 5th-century-bce Greek historians Herodotus and Thucydides referred to epibatai, or heavy-armed sea soldiers in the Greek fleets, while Polybius, in the 3rd–2nd century bce, described milites classiarii (“soldiers of the fleet”), a category of Roman soldiers organized and specially armed for duty aboard warships.
During the Middle Ages, ordinary soldiers in Europe were frequently embarked aboard ship to provide a fighting backbone, but not until the naval wars of the 17th century was the distinct and organized role of marines almost simultaneously rediscovered by the British and Dutch, who raised the first two modern corps of marines—the Duke of York and Albany’s Maritime Regiment of Foot (1664; renamed the Royal Marine in 1802) and the Koninklijke Nederlandse Corps Mariniers (1665), respectively. The United States Marine Corps, organized in 1775, has become the most famous organization of the kind, but other countries also maintain marine corps.