The United States Marine Corps (USMC), also referred to as the United States Marines, is the
maritime land force service branch of the
United States Armed Forces responsible for conducting
expeditionary and
amphibious operations through
combined arms, implementing its own
infantry,
artillery,
aerial, and
special operations forces. The U.S. Marine Corps is one of the eight
uniformed services of the United States.
The Marine Corps has been part of the
U.S. Department of the Navy
The United States Department of the Navy (DoN) is one of the three military departments within the United States Department of Defense, Department of Defense of the United States of America. It was established by an Act of Congress on 30 April ...
since 30 June 1834 with its sister service, the
United States Navy. The USMC operates
installations on land and aboard sea-going
amphibious warfare ships around the world. Additionally, several of the Marines' tactical
aviation squadrons, primarily Marine Fighter Attack squadrons, are also embedded in Navy
carrier air wings and operate from the
aircraft carrier
An aircraft carrier is a warship that serves as a seagoing airbase, equipped with a full-length flight deck and facilities for carrying, arming, deploying, and recovering aircraft. Typically, it is the capital ship of a fleet, as it allows a ...
s.
The history of the Marine Corps began when two
battalions of
Continental Marines were formed on 10 November 1775 in
Philadelphia as a service branch of infantry troops capable of fighting both at sea and on shore. In the
Pacific theater
The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...
of
World War II the Corps took the lead in a massive campaign of amphibious warfare,
advancing from island to island.
As of 2022, the USMC has around 177,200 active duty members and some 32,400 personnel in
reserve.
Mission
As outlined in and as originally introduced under the
National Security Act of 1947
The National Security Act of 1947 ( Pub.L.br>80-253 61 Stat.br>495 enacted July 26, 1947) was a law enacting major restructuring of the United States government's military and intelligence agencies following World War II. The majority of the pro ...
, three primary areas of responsibility for the U.S. Marine Corps are:
* Seizure or defense of advanced naval bases and other land operations to support
naval campaigns;
* Development of tactics, technique, and equipment used by amphibious landing forces in coordination with the
Army and
Air Force; and
* Such other duties as the
President or
Department of Defense may direct.
This last clause derives from similar language in the
Congressional
A congress is a formal meeting of the representatives of different countries, constituent states, organizations, trade unions, political parties, or other groups. The term originated in Late Middle English to denote an encounter (meeting of ...
acts ''"For the Better Organization of the Marine Corps"'' of 1834, and ''"Establishing and Organizing a Marine Corps"'' of 1798. In 1951, the
House of Representatives' Armed Services Committee called the clause "one of the most important statutory – and traditional – functions of the Marine Corps". It noted that the Corps has more often than not performed actions of a non-naval nature, including its famous actions in
Tripoli, the
War of 1812,
Chapultepec, and numerous
counter-insurgency
Counterinsurgency (COIN) is "the totality of actions aimed at defeating irregular forces". The Oxford English Dictionary defines counterinsurgency as any "military or political action taken against the activities of guerrillas or revolutionar ...
and occupational duties (such as those in Central America,
World War I, and the
Korean War). While these actions are not accurately described as support of naval campaigns nor as amphibious warfare, their common thread is that they are of an expeditionary nature, using the mobility of the Navy to provide timely intervention in foreign affairs on behalf of American interests.
The
Marine Band, dubbed the "President's Own" by
Thomas Jefferson, provides music for state functions at the
White House. Marines from Ceremonial Companies A & B, quartered in
Marine Barracks, Washington, D.C.
Marine Barracks, Washington, D.C. is located at the corner of 8th and I Streets, Southeast in Washington, D.C. Established in 1801, it is a National Historic Landmark, the oldest post in the United States Marine Corps, the official residence of t ...
, guard presidential retreats, including
Camp David
Camp David is the country retreat for the president of the United States of America. It is located in the wooded hills of Catoctin Mountain Park, in Frederick County, Maryland, near the towns of Thurmont and Emmitsburg, about north-northwe ...
, and the marines of the Executive Flight Detachment of
HMX-1
Marine Helicopter Squadron One (HMX-1) is a United States Marine Corps helicopter squadron responsible for the transportation of the president and vice president of the United States, heads of state, Department of Defense officials, and other VIPs ...
provide helicopter transport to the President and
Vice President, with the radio call signs "
Marine One
Marine One is the call sign of any United States Marine Corps aircraft carrying the president of the United States. It usually denotes a helicopter operated by Marine Helicopter Squadron One ( HMX-1) "Nighthawks", consisting of either the larg ...
" and "Marine Two", respectively. The Executive Flight Detachment also provides helicopter transport to
Cabinet members and other
VIPs. By authority of the 1946 Foreign Service Act, the
Marine Security Guards of the Marine Embassy Security Command provide security for American
embassies,
legation
A legation was a diplomatic representative office of lower rank than an embassy. Where an embassy was headed by an ambassador, a legation was headed by a Envoy Extraordinary and Minister Plenipotentiary, minister. Ambassadors diplomatic rank, out ...
s, and
consulates at more than 140 posts worldwide.
The relationship between the
Department of State
The United States Department of State (DOS), or State Department, is an executive department of the U.S. federal government responsible for the country's foreign policy and relations. Equivalent to the ministry of foreign affairs of other nati ...
and the U.S. Marine Corps is nearly as old as the Corps itself. For over 200 years, marines have served at the request of various
Secretaries of State. After
World War II, an alert, disciplined force was needed to protect American embassies, consulates, and legations throughout the world. In 1947, a proposal was made that the Department of Defense furnishes Marine Corps personnel for Foreign Service guard duty under the provisions of the Foreign Service Act of 1946. A formal Memorandum of Agreement was signed between the Department of State and the
Secretary of the Navy on 15 December 1948, and 83 marines were deployed to overseas missions. During the first year of the program, 36 detachments were deployed worldwide.
Historical mission
The Marine Corps was founded to serve as an infantry unit aboard naval vessels and was responsible for the security of the ship and its crew by conducting offensive and defensive combat during
boarding actions and defending the ship's officers from
mutiny
Mutiny is a revolt among a group of people (typically of a military, of a crew or of a crew of pirates) to oppose, change, or overthrow an organization to which they were previously loyal. The term is commonly used for a rebellion among member ...
; to the latter end, their quarters on the ship were often strategically positioned between the officers' quarters and the rest of the vessel. Continental Marines manned raiding parties, both at sea and ashore. America's first amphibious assault landing occurred early in the
Revolutionary War on 3 March 1776 as the Marines gained control of
Fort Montagu and
Fort Nassau, a
British ammunition depot and naval port in
New Providence
New Providence is the most populous island in the Bahamas, containing more than 70% of the total population. It is the location of the national capital city of Nassau, whose boundaries are coincident with the island; it had a population of 246 ...
, the Bahamas. The role of the Marine Corps has expanded significantly since then; as the importance of its original naval mission declined with changing naval warfare doctrine and the professionalization of the naval service, the Corps adapted by focusing on formerly secondary missions ashore. The Advanced Base Doctrine of the early 20th century codified their combat duties ashore, outlining the use of marines in the seizure of bases and other duties on land to support naval campaigns.
Throughout the late 19th and 20th centuries, Marine detachments served aboard Navy cruisers, battleships and aircraft carriers. Marine detachments served in their traditional duties as a ship's landing force, manning the ship's weapons and providing shipboard security. Marine detachments were augmented by members of the ship's company for landing parties, such as in the
First Sumatran expedition of 1832, and continuing in the Caribbean and
Mexican campaigns of the early 20th centuries. Marines developed tactics and techniques of amphibious assault on defended coastlines in time for use in World War II.
During World War II, marines continued to serve on capital ships. They often were assigned to man anti-aircraft batteries.
In 1950, President
Harry Truman responded to a message from U.S. Representative
Gordon L. McDonough
Gordon Leo McDonough (January 2, 1895 – June 25, 1968) was an American politician who served as a U.S. Representative from Californiafrom 1945 to 1963.
Early life and career
Born in Buffalo, New York, McDonough moved with his parents to Empo ...
. McDonough had urged President Truman to add Marine representation on the
Joint Chiefs of Staff. President Truman, writing in a letter addressed to McDonough, stated that "The Marine Corps is the Navy's police force and as long as I am President that is what it will remain. They have a propaganda machine that is almost equal to
Stalin's." McDonough then inserte
President Truman's letter dated 29 August 1950, into the ''
Congressional Record
The ''Congressional Record'' is the official record of the proceedings and debates of the United States Congress, published by the United States Government Publishing Office and issued when Congress is in session. The Congressional Record Inde ...
''. Congressmen and Marine organizations reacted, calling President Truman's remarks an insult and demanded an apology. Truman apologized to the Marine commandant at the time, writing, "I sincerely regret the unfortunate choice of language which I used in my letter of August 29 to Congressman McDonough concerning the Marine Corps." While Truman had apologized for his metaphor, he did not alter his position that the Marine Corps should continue to report to the Navy secretary. He made amends only by making a surprise visit to the
Marine Corps League
The Marine Corps League is the only congressionally chartered United States Marine Corps-related veterans organization in the United States. Its congressional charter was approved by the 75th U.S. Congress and signed by President Franklin D. Roo ...
a few days later, when he reiterated, "When I make a mistake, I try to correct it. I try to make as few as possible." He received a standing ovation.
When gun cruisers were retired by the 1960s, the remaining Marine detachments were only seen on battleships and carriers. Its original mission of providing shipboard security ended in the 1990s.
Capabilities
The Marine Corps fulfills a critical military role as an amphibious warfare force. It is capable of
asymmetric warfare with
conventional,
irregular, and
hybrid forces. While the Marine Corps does not employ any unique capabilities, as a force it can rapidly deploy a combined-arms task force to almost anywhere in the world within days. The basic structure for all deployed units is a
Marine Air-Ground Task Force
Marine Air-Ground Task Force (MAGTF, pronounced MAG-TAF) is a term used by the United States Marine Corps to describe the principal organization for all missions across the range of military operations. MAGTFs are a balanced air-ground, combined ar ...
(MAGTF) that integrates a
ground combat element, an
aviation combat element and a
logistics combat element under a common
command element
In the United States Marine Corps, the command element (CE) is the command and control force of a Marine Air-Ground Task Force (MAGTF). It provides C3I for the MAGTF.
__TOC__
Role within the MAGTF
The Command Element (CE), a headquarters unit ...
. While the creation of joint commands under the
Goldwater–Nichols Act
The Goldwater–Nichols Department of Defense Reorganization Act of October 4, 1986 , (signed by President Ronald Reagan), made the most sweeping changes to the United States Department of Defense since the department was established in the ...
has improved inter-service coordination between each branch, the Corps's ability to permanently maintain integrated multi-element task forces under a single command provides a smoother implementation of combined-arms warfare principles.

The close integration of disparate Marine units stems from an organizational culture centered on the infantry. Every other Marine capability exists to support the infantry. Unlike some Western militaries, the Corps remained conservative against theories proclaiming the ability of new weapons to win wars independently. For example,
Marine aviation has always been focused on
close air support
In military tactics, close air support (CAS) is defined as air action such as air strikes by fixed or rotary-winged aircraft against hostile targets near friendly forces and require detailed integration of each air mission with fire and moveme ...
and has remained largely uninfluenced by air power theories proclaiming that
strategic bombing can single-handedly win wars.
This focus on the infantry is matched with the doctrine of "Every marine
sa rifleman", a precept of Commandant
Alfred M. Gray, Jr.
Alfred Mason Gray Jr. (born June 22, 1928) is a retired United States Marine Corps four-star general who served as the 29th Commandant of the Marine Corps from 1 July 1987 until his retirement on 30 June 1991 after 41 years of service.
Early li ...
, emphasizing the infantry combat abilities of every marine. All marines, regardless of
military specialization, receive training as a
rifleman; and all officers receive additional training as infantry platoon commanders. During World War II at the
Battle of Wake Island, when all of the Marine aircraft were destroyed, pilots continued the fight as ground officers, leading supply clerks and cooks in a final defensive effort.
Flexibility of execution is implemented via an emphasis on "
commander's intent" as a guiding principle for carrying out orders, specifying the end state but leaving open the method of execution.
The amphibious assault techniques developed for World War II evolved, with the addition of
air assault
Air assault is the movement of ground-based military forces by vertical take-off and landing (VTOL) aircraft—such as the helicopter—to seize and hold key terrain which has not been fully secured, and to directly engage enemy forces behind e ...
and
maneuver warfare doctrine, into the current "''Operational Maneuver from the Sea''" doctrine of
power projection
Power projection (or force projection or strength projection), in international relations, is the capacity of a state to deploy and sustain forces outside its territory. The ability of a state to project its power into an area may serve as an e ...
from the seas.
The Marines are credited with the development of helicopter insertion doctrine and were the earliest in the American military to widely adopt maneuver-warfare principles, which emphasize low-level initiative and flexible execution. In light of recent warfare that has strayed from the Corps's traditional missions,
the Marines have renewed an emphasis on amphibious capabilities.

The Marine Corps relies on the Navy for
sealift to provide its rapid deployment capabilities. In addition to basing a third of the
Fleet Marine Force in Japan,
Marine expeditionary units (MEU) are typically stationed at sea so they can function as first responders to international incidents.
To aid rapid deployment, the
Maritime Pre-Positioning System was developed: fleets of
container ships are positioned throughout the world with enough equipment and supplies for a
marine expeditionary force to deploy for 30 days.
Doctrine
Two small manuals published during the 1930s established USMC doctrine in two areas. The ''
Small Wars Manual
The ''Small Wars Manual'' is a United States Marine Corps manual on tactics and strategies for engaging in certain types of military operations.
The Marine Corps' role in small wars has a long and complex history. During the early years of the 2 ...
'' laid the framework for Marine
counter-insurgency
Counterinsurgency (COIN) is "the totality of actions aimed at defeating irregular forces". The Oxford English Dictionary defines counterinsurgency as any "military or political action taken against the activities of guerrillas or revolutionar ...
operations from
Vietnam to
Iraq and
Afghanistan while the ''Tentative Landing Operations Manual'' established the doctrine for the
amphibious operations of World War II. "''Operational Maneuver from the Sea''" was the doctrine of power projection in 2006.
History
Foundation and American Revolutionary War

The United States Marine Corps traces its roots to the
Continental Marines of the
American Revolutionary War, formed by Captain
Samuel Nicholas
Samuel Nicholas (1744 – 27 August 1790) was the first officer commissioned in the United States Continental Marines (predecessor to the United States Marine Corps) and by tradition is considered to be the first Commandant of the Marine Corps ...
by a resolution of the
Second Continental Congress
The Second Continental Congress was a late-18th-century meeting of delegates from the Thirteen Colonies that united in support of the American Revolutionary War. The Congress was creating a new country it first named "United Colonies" and in 1 ...
on 10 November 1775, to raise two
battalions of marines. This date is celebrated as the
birthday of the Marine Corps. Nicholas was nominated to lead the Marines by
John Adams. By December 1775, Nicholas raised one battalion of 300 men by recruitment in his home city of Philadelphia.
In January 1776, the Marines went to sea under the command of Commodore
Esek Hopkins
Esek Hopkins (April 26, 1718February 26, 1802) was an American naval officer, merchant captain, and privateer. Achieving the rank of Commodore, Hopkins was the only Commander in Chief of the Continental Navy during the American Revolutionary War ...
and in March undertook their first amphibious landing, the
Battle of Nassau in the Bahamas, occupying the British port of Nassau for two weeks.
On 3 January 1777, the Marines arrived at the
Battle of Princeton
The Battle of Princeton was a battle of the American Revolutionary War, fought near Princeton, New Jersey on January 3, 1777, and ending in a small victory for the Colonials. General Lord Cornwallis had left 1,400 British troops under the comman ...
attached to General
John Cadwalader's brigade, where they had been assigned by General
George Washington
George Washington (February 22, 1732, 1799) was an American military officer, statesman, and Founding Father who served as the first president of the United States from 1789 to 1797. Appointed by the Continental Congress as commander of th ...
; by December 1776, Washington was retreating through New Jersey and, "in desperate need of veteran soldiers," had ordered Nicholas and the Marines to attach themselves to the
Continental Army
The Continental Army was the army of the United Colonies (the Thirteen Colonies) in the Revolutionary-era United States. It was formed by the Second Continental Congress after the outbreak of the American Revolutionary War, and was establis ...
. The
Battle of Princeton
The Battle of Princeton was a battle of the American Revolutionary War, fought near Princeton, New Jersey on January 3, 1777, and ending in a small victory for the Colonials. General Lord Cornwallis had left 1,400 British troops under the comman ...
, where the Marines along with General Cadwalader's brigade were personally rallied by Washington, was the first land combat engagement of the Marines; an estimated 130 marines were present at the battle.
At the end of the American Revolution, both the
Continental Navy
The Continental Navy was the navy of the United States during the American Revolutionary War and was founded October 13, 1775. The fleet cumulatively became relatively substantial through the efforts of the Continental Navy's patron John Adams ...
and Continental Marines were disbanded in April 1783. The institution was resurrected on 11 July 1798; in preparation for the
Quasi-War with
France, Congress created the United States Marine Corps. Marines had been enlisted by the
War Department as early as August 1797 for service in the newly-built
frigate
A frigate () is a type of warship. In different eras, the roles and capabilities of ships classified as frigates have varied somewhat.
The name frigate in the 17th to early 18th centuries was given to any full-rigged ship built for speed and ...
s authorized by the Congressional "Act to provide a Naval Armament" of 18 March 1794, which specified the numbers of marines to recruit for each frigate.
The Marines' most famous action of this period occurred during the
First Barbary War (1801–1805) against the
Barbary pirates
The Barbary pirates, or Barbary corsairs or Ottoman corsairs, were Muslim pirates and privateers who operated from North Africa, based primarily in the ports of Salé, Rabat, Algiers, Tunis and Tripoli, Libya, Tripoli. This area was known i ...
, when
William Eaton and First Lieutenant
Presley O'Bannon led 8 marines and 500
mercenaries
A mercenary, sometimes also known as a soldier of fortune or hired gun, is a private individual, particularly a soldier, that joins a military conflict for personal profit, is otherwise an outsider to the conflict, and is not a member of any o ...
in an effort to capture
Tripoli. Though they only reached
Derna, the action at Tripoli has been immortalized in the
Marines' Hymn and the
Mameluke sword carried by Marine officers.
War of 1812 and afterward

During the
War of 1812, Marine detachments on Navy ships took part in some of the great frigate duels that characterized the war, which were the first and last engagements of the conflict. Their most significant contribution was holding the center of General
Andrew Jackson's defensive line at the 1815
Battle of New Orleans, the final major battle and one of the most one-sided engagements of the war. With widespread news of the battle and the
capture of HMS ''Cyane'', HMS ''Levant'' and
HMS ''Penguin'', the final engagements between British and U.S. forces, the Marines had gained a reputation as expert
marksmen, especially in defensive and ship-to-ship actions.
They played a large role in the 1813
defense of Sacket's Harbor, New York and
Norfolk and Portsmouth, Virginia, also taking part in the 1814
defense of Plattsburgh in the
Champlain Valley during one of the final British offensives along the Canadian-U.S. border. The
battle of Bladensburg, fought 24 August 1814, was one of the worst days for American arms, though a few units and individuals performed heroic service. Notable among them were Commodore Joshua Barney's 500 sailors and the 120 marines under Captain Samuel Miller USMC, who inflicted the bulk of British casualties and were the only effective American resistance during the battle. A final desperate Marine counter attack, with the fighting at close quarters, however was not enough; Barney and Miller's forces were overrun. In all of 114 marines, 11 were killed and 16 wounded. During the battle Captain Miller's arm was badly wounded, for his gallant service in action, Miller was brevetted to the rank of Major USMC.

After the war, the Marine Corps fell into a malaise that ended with the appointment of
Archibald Henderson as its fifth commandant in 1820. Under his tenure, the Corps took on expeditionary duties in the Caribbean, the