Member of a military force trained for service at sea and in land operations related to naval campaigns. They existed as far back as the 5th century BC, when the Greek fleets were manned by epibatai, or heavily armed sea soldiers. In the Middle Ages ordinary soldiers were often assigned to shipboard duty; not until the naval wars of the 17th century was the distinct role of marines rediscovered almost simultaneously by the British and the Dutch, who raised the first two modern marine corps, the Royal Marine (1664) and the Koninklijke Nederlandse Corps Mariniers (1665). See alsoU.S. Marine Corps.