The United States Marine Corps (USMC)

The United States Marine Corps (USMC) is the maritime land force service branch of the United States Armed Forces and part of the civilian-led Department of the Navy, which is led by the Secretary of the Navy. The military head of the U.S. Marine Corps is the commandant of the Marine Corps, who is assisted by the assistant commandant of the Marine Corps and sergeant major of the Marine Corps. The Marine Corps was founded on 10 November 1775 as the Continental Marines and disbanded in 1783, before being reestablished as the United States Marine Corps on 11 July 1798.

Marine Corps is responsible for amphibious warfare and expeditionary warfare operations, having a very close relationship with its coequal sister service, the United States Navy. The U.S. Marine Corps is composed of the Regular Marine Corps and the United States Marine Corps Reserve. The central unit of the Marine Corps is a Marine Air-Ground Task Force, which consist of a command element, ground combat element, aviation combat element, and logistics combat element. The Marine Corps is divided in the Fleet Marine Force and the Supporting Establishment.

The U.S. Marine Corps' Marine Air-Ground Task Force structure is broken into several levels under the Fleet Marine Force:

Marine Expeditionary Force: The largest type of Marine Air-Ground Task Force, consists of a marine division, air wing, and logistics group under a headquarters group and 20,000 to 90,000 marines and sailors commanded by a lieutenant general. The principal warfighting organization of the Marine Corps during larger crisis or contingencies, MEFs' are self-sufficient for 60 days.

Marine Expeditionary Brigade: The medium type of Marine Air-Ground task Force, consists of a reinforced infantry regiment, reinforced composite marine aircraft group, and task organized logistics combat regiment under a command element and 20,000 marines and sailors commanded by a brigadier general. Forward deployed MEUs provide an expeditionary force in readiness and are self-sufficient for 30 days.

Marine Expeditionary Unit: The light type of Marine Air-Ground task Force, consists of a reinforced infantry battalion, reinforced composite aviation squadron, and task organized combat logistics battalion command element and 2,600 marines and sailors commanded by a colonel. Forward deployed MEUs provide an expeditionary force in readiness, capable of commencing missions on a six-hour timeline and are self-sufficient for 15 days.
The U.S. Marine Corps' unit structure is broken into several subdivisions under the Fleet Marine Force:

 Marine division / Marine aircraft wing: Consists of three marine regiments or marine aircraft groups and 6,561 marines commanded by a major general.
 
Marine logistics group: Consists of three combat logistics regiments and commanded by a brigadier general.
  
Marine regiment / Marine aircraft group: Consist of three or more marine battalions or marine aviation squadrons and 2,187 marines commanded by a colonel.
 
Marine battalion / Marine aviation squadron: Consists of three or more companies or 24 aircraft and 729 marines commanded by a lieutenant colonel.
 
Company: Consists of three or more platoons and 243 marines commanded by a Captain.
 
Platoon: Consists of three squads and 27 marines commanded by a first lieutenant or second lieutenant.
 
Squad / Section: Consists of three teams and nine marines led by a sergeant.
 
Fire team: Consists of four marines led by a corporal.