How the U.S. Marines Work

Marines logo
Photo courtesy of the The U.S. Marines
The U.S. Marine Corps logo
Of the four branches of the U.S. military that fall within the Department of Defense (Army, Navy, Air Force, Marines), the United States Marine Corps is by far the smallest. Yet the Marines have taken on some of the toughest missions military planners can throw at them, and have developed a unique military culture that thrives on challenge and hardship. In fact, all Marines proudly declare that there are no “former” or “ex” Marines – a Marine stays a Marine for life.

In this article we'll look at why there is a Marine Corps, how it's structured, the history behind the Corps, how to join, life inside, and leaving.

Marine Corps Purpose
The modern Marine Corps is focused on “force projection;” specifically, the projection of U.S. military power from Navy ships onto hostile landing areas. Marines have spearheaded amphibious assaults and gained footholds for American troops throughout U.S. history. They secure or set up advance bases from which the Army and Air Force can operate. In addition, the Marines can be used for “other duties as the President may direct,” according to the 1834 Marine Corps Law. The Marines operate in a state of readiness for combat unmatched by units in other military branches. A Marine unit has everything it needs to leap right into combat, including logistical support and close air support. Plus, the Marines keep units stationed on Navy ships that are “on float” around the world. That puts them closer to potential trouble spots than troops stationed in the United States

Amphibious assault ship
Photo courtesy of the U.S. Marines/Photographer Lance Cpl. Lucian Friel
An amphibious assault vehicle during ship operation training.

The Marines and the Navy
Although the Marine Corps is separate from the Navy, the two forces both operate under the Department of the Navy and have a close relationship. Marine forces often provide security on Navy ships, and many Navy ships have Marine units stationed on them (including an air wing) on a semi-permanent basis. Certain “behind the scenes” jobs, such as chaplains or medics, are filled in the Marine Corps ranks by Navy personnel because the Marines don’t train those positions. These personnel wear Marine uniforms with Navy insignias. Marine officers are trained at the Naval Academy, and Navy officer training includes some training by a Marine Corps drill instructor.

The “as the President may direct” portion of the Marine Corps’ job description puts them in quite a few non-amphibious situations, including combat far from beaches, running security detail on some Navy ships (originally the Corps’ primary function), protecting U.S. embassies as well as the White House, and transporting the president and vice president in Marine helicopters.