United States Marine Corps (USMC) Mission and Organizational Fundamentals

The mission of the Marine Corps is outlined in the National Security Act of 1947 as amended (1952).
The official mission of the Marine Corps is established in the National Security Act of 1947, amended in 1952.  Marines are trained, organized and equipped for  Offensive amphibious employment and as a “force in readiness.”  According to the Act, Marines stand prepared to meet mission requirements.

There are Seven Elements of the Marine Corps Mission

a. Provide Fleet Marine Force with combined arms and supporting air components
for service with the United States Fleet in the seizure or defense of advanced
naval bases and for the conduct of such land operations as may be essential to
the execution of naval campaign.

b. Provide detachments and organizations for service on armed vessels of the
Navy and security detachments for the protection of naval property at naval
Stations and bases.

c. Develop, in coordination with the Army, Navy, and Air Force, the doctrine,
tactics, techniques, and equipment employed by landing forces in amphibious
operations.

d. Provide Marine forces for airborne operations, in coordination with the Army,
Navy, and Air Force, according to the doctrine established by the Joint Chiefs

of Staff.
e. Develop, in coordination with the Army, Navy, and Air Force, the doctrine,
procedures, and equipment for airborne operations.

f. Expand peacetime components to meet wartime needs according to the joint
mobilization plans.

g. Perform such other duties as the President may direct.
The Marines are often referred to as the “Infantry of the Navy.” Marines specialize in amphibious operations. In other words, their primary specialty is to assault, capture, and control “beach heads,” 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 military service. The Marines are an elite fighting force. While amphibious operations are their primary specialty, in recent years, the Marines have expanded their equipment and training for other ground-combat operations, as well. The Marines are generally a “lighter” force when compared to the Army, so they can generally be deployed fast (although the Army has been making great strides in “rapid deployment” in the past few years). For combat operations, the Marines like to be self-sufficient, as much as possible, so they also have their own air power, consisting primarily of fighter and fighter/bomber aircraft and attack helicopters (that way, they don’t have to ask the Air Force or Navy for air support). Even so, the Marines use the Navy for much of their logistical and administrative support. For example, there are no doctors, nurses, or enlisted medics in the Marine Corps. Those functions are handled by the Navy. Even medics that accompany the Marines into combat are specially-trained Navy medics. With the exception of the Coast Guard, the Marines are also the smallest service. There are approximately 18,000 officers and 153,000 enlisted personnel on active duty in the Marines. Like the Navy, there is no Marine Corps National Guard, but Marines are supported in times of need by the Marine Corps Reserves.

This should answer the questions:

Where is the mission of the Marine Corps outlined?
What is the National Security Act of 1947 as amended (1952)?
What is the mission of the Marine Corps?