Marines specialize in amphibious operations; their primary specialty is to assault, capture, and control beachheads, which then provide a route to attack the enemy from almost any direction.

The Marines were officially established on 10 November 1775 by the Continental Congress to act as a landing force for the United States Navy. In 1798, however, Congress established the Marine Corps as a separate service. While amphibious operations are their primary specialty, in recent years, the Marines have expanded other ground-combat operations, as well.

For combat operations, the Marine Corps likes to be self-sufficient, so it also has its own air power, consisting primarily of fighter and fighter/bomber aircraft and attack helicopters. But the Marines do use the Navy for logistical and administrative support; there are no doctors, nurses, or enlisted medics in the Marine Corps, for instance. Even medics that accompany the Marines into combat are specially-trained Navy medics.