United States Marine Corps

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; 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, 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.[24] During World War II, Marines continued to serve on capital ships. They often were assigned to man anti-aircraft batteries.

In 1950,[25] President Harry Truman responded to a message from U.S. Representative Gordon L. McDonough. 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 inserted President Truman's letter, dated 29 August 1950, into the Congressional Record. 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 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.[26]

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.

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 (MAGTF) that integrates a ground combat element, an aviation combat element and a logistics combat element under a common command element. While the creation of joint commands under the Goldwater–Nichols Act has improved inter-service coordination between each branch, the Corps' ability to permanently maintain integrated multi-element task forces under a single command provides a smoother implementation of combined-arms warfare principles.[27]

U.S. Marines from the 31st Marine Expeditionary Unit training

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 and has remained largely uninfluenced by air power theories proclaiming that strategic bombing can single-handedly win wars.[24]

This focus on the infantry is matched with the doctrine of "Every Marine [is] a rifleman", a precept of Commandant Alfred M. Gray, Jr., 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.[28] 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.[29] 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.[30]

The amphibious assault techniques developed for World War II evolved, with the addition of air assault and maneuver warfare doctrine, into the current "Operational Maneuver from the Sea" doctrine of power projection from the seas.[12] 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' traditional missions,[31] it has renewed an emphasis on amphibious capabilities.[32]

Marines from the 15th Marine Expeditionary Unit depart USS Tarawa (LHA-1), using both a Landing Craft Utility and CH-53E "Super Stallion" helicopters, during amphibious operations in Kuwait, 2003.

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.[33] 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.

The USMC is planning to reduce its logistical requirements and by 2025 eliminate all liquid fuel use for Marine Expeditionary Forces, except for highly efficient vehicles.[34]

Two small manuals published during the 1930s established USMC doctrine in two areas. The Small Wars Manual laid the framework for Marine counter-insurgency 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" is the current doctrine of power projection.[12]

Maj. Samuel Nicholas, first Commandant of the Marine Corps, was nominated to lead the Continental Marines by John Adams in November 1775.

The United States Marine Corps traces its roots to the Continental Marines of the American Revolutionary War, formed by Captain Samuel Nicholas by a resolution of the Second Continental Congress 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.[35] By December 1775, Nicholas raised one battalion of 300 men by recruitment in his home city of Philadelphia.

Continental Marines landing at New Providence in March 1776 during the Battle of Nassau, the first amphibious landing of the Marine Corps, during the American Revolutionary War

In January 1776, the Marines went to sea under the command of Commodore Esek Hopkins and in March undertook their first amphibious landing, the Battle of Nassau in the Bahamas, occupying the British port of Nassau for two weeks.[36] On 3 January 1777, the Marines arrived at the Battle of Princeton attached to General John Cadwalader’s brigade, where they had been assigned by General George Washington; 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 Battle of Princeton, 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.[36]

At the end of the American Revolution, both the Continental Navy 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.[37] Marines had been enlisted by the War Department as early as August 1797[38] for service in the newly-built frigates authorized by the Congressional "Act to provide a Naval Armament" of 18 March 1794,[39] which specified the numbers of Marines to recruit for each frigate.

U.S. Marines leading Arab mercenaries to victory under U.S. Navy Lieutenant William Eaton and U.S. Marine Corps First Lieutenant Presley O'Bannon during the Battle of Derna

The Marines' most famous action of this period occurred during the First Barbary War (1801–1805) against the Barbary pirates,[40] when William Eaton and First Lieutenant Presley O'Bannon led 8 Marines and 500 mercenaries 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.[41]

British and U.S. troops garrisoned aboard Hornet and Penguin exchanging small arms musket fire with Tristan da Cuna in the background during the final engagement between British and U.S. forces in the War of 1812

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.[41] They played a large role in the 1813 defense of Sacket's Harbor, New York and Norfolk and Portsmouth, Virginia,[42] also taking part in the 1814 defense of Plattsburgh in the Champlain Valley during one of the final British offensives along the Canadian-American border.

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 Gulf of Mexico, Key West, West Africa, the Falkland Islands, and Sumatra. Commandant Henderson is credited with thwarting President Jackson's attempts to combine and integrate the Marine Corps with the Army.[41] Instead, Congress passed the Act for the Better Organization of the Marine Corps in 1834, stipulating that the Corps was part of the Department of the Navy as a sister service to the Navy.[43] This would be the first of many times that the independent existence of the Corps was challenged.

U.S. Marines storming Chapultepec castle under a large American flag, paving the way for the fall of Mexico City

Commandant Henderson volunteered the Marines for service in the Seminole Wars of 1835, personally leading nearly half of the entire Corps (two battalions) to war. A decade later, in the Mexican–American War (1846–1848), the Marines made their famed assault on Chapultepec Palace in Mexico City, which would be later celebrated as the "Halls of Montezuma" in the Marines' Hymn. In fairness to the U.S. Army, most of the troops who made the final assault at the Halls of Montezuma were soldiers and not Marines.[44] The Americans forces were led by Army General Winfield Scott. Scott organized two storming parties of about 250 men each for 500 men total including 40 Marines.

In the 1850s, the Marines engaged in service in Panama and Asia and were attached to Commodore Matthew Perry's East India Squadron on its historic trip to the Far East.[45]

Five USMC privates with fixed bayonets, and their NCO with his sword at the Washington Navy Yard, 1864

The Marine Corps played a small role in the Civil War (1861–1865); their most prominent task was blockade duty. As more and more states seceded from the Union, about a third of the Corps' officers left the United States to join the Confederacy and form the Confederate States Marine Corps, which ultimately played little part in the war. The battalion of recruits formed for the First Battle of Bull Run performed poorly, retreating with the rest of the Union forces.[33] Blockade duty included sea-based amphibious operations to secure forward bases. In late November 1861, Marines and sailors landed a reconnaissance in force from USS Flag at Tybee Island, Georgia, to occupy the Lighthouse and Martello Tower on the northern end of the island. It would later be the Army base for bombardment of Fort Pulaski.[46] In April and May 1862, Union Marines participated in the capture and occupation of New Orleans and the occupation of Baton Rouge, Louisiana,[47] key events in the war that helped secure Union control of the lower Mississippi River basin and denied the Confederacy a major port and naval base on the Gulf Coast.

The remainder of the 19th century was marked by declining strength and introspection about the mission of the Marine Corps. The Navy's transition from sail to steam put into question the need for Marines on naval ships. Meanwhile, Marines served as a convenient resource for interventions and landings to protect American interests overseas. The Corps was involved in over 28 separate interventions in the 30 years from the end of the American Civil War to the end of 19th century.[48] They were called upon to stem political and labor unrest within the United States.[49] Under Commandant Jacob Zeilin's tenure, Marine customs and traditions took shape: the Corps adopted the Marine Corps emblem on 19 November 1868. It was during this time that "The Marines' Hymn" was first heard. Around 1883, the Marines adopted their current motto "Semper fidelis" (Always Faithful).[41] John Philip Sousa, the musician and composer, enlisted as a Marine apprentice at age 13, serving from 1867 until 1872, and again from 1880 to 1892 as the leader of the Marine Band.

During the Spanish–American War (1898), Marines led American forces ashore in the Philippines, Cuba, and Puerto Rico, demonstrating their readiness for deployment. At Guantánamo Bay, Cuba, the Marines seized an advanced naval base that remains in use today. Between 1899 and 1916, the Corps continued its record of participation in foreign expeditions, including the Philippine–American War, the Boxer Rebellion in China, Panama, the Cuban Pacifications, the Perdicaris incident in Morocco, Veracruz, Santo Domingo, and the Banana Wars in Haiti and Nicaragua; the experiences gained in counter-insurgency and guerrilla operations during this period were consolidated into the Small Wars Manual.[50]

Georges Scott, American Marines in Belleau Wood, 1918

During World War I, Marines served as a part of the American Expeditionary Force under General John J. Pershing when America entered into the war on 6 April 1917. The Marine Corps had a deep pool of officers and non-commissioned officers with battle experience and thus experienced a large expansion. The U.S. Marine Corps entered the war with 511 officers and 13,214 enlisted personnel and by 11 November 1918 had reached a strength of 2,400 officers and 70,000 enlisted.[51] African-Americans were entirely excluded from the Marine Corps during this conflict.[52] Opha May Johnson was the first woman to enlist in the Marines; she joined the Marine Corps Reserve in 1918 during World War I, officially becoming the first female Marine.[53] From then until the end of World War I, 305 women enlisted in the Corps.[54] During the Battle of Belleau Wood in 1918, the Marines and U.S. media reported that Germans had nicknamed them Teufel Hunden, meaning "Devil Dogs" for their reputation as shock troops and marksmen at ranges up to 900 meters; there is no evidence of this in German records (as Teufelshunde would be the proper German phrase). Nevertheless, the name stuck in U.S. Marine lore.[55]

The flag of the United States Marine Corps from 1914 to 1939

Between the World Wars, the Marine Corps was headed by Commandant John A. Lejeune, and under his leadership, the Corps studied and developed amphibious techniques that would be of great use in World War II. Many officers, including Lieutenant Colonel Earl Hancock "Pete" Ellis, foresaw a war in the Pacific with Japan and undertook preparations for such a conflict. Through 1941, as the prospect of war grew, the Corps pushed urgently for joint amphibious exercises with the Army and acquired amphibious equipment that would prove of great use in the upcoming conflict.[56]

Former French Foreign Legion Lieutenant, and U.S. Marine Corps officer Peter J. Ortiz, who served in the European theater, often behind enemy lines

In World War II, the Marines performed a central role in the Pacific War, along with the U.S. Army. The battles of Guadalcanal, Bougainville, Tarawa, Guam, Tinian, Cape Gloucester, Saipan, Peleliu, Iwo Jima, and Okinawa saw fierce fighting between Marines and the Imperial Japanese Army. Some 600,000 Americans served in the U.S. Marine Corps in World War II.[57]

The Battle of Iwo Jima, which began on 19 February 1945, was arguably the most famous Marine engagement of the war. The Japanese had learned from their defeats in the Marianas Campaign and prepared many fortified positions on the island including pillboxes and network of tunnels. The Japanese put up fierce resistance, but American forces reached the summit of Mount Suribachi on 23 February. The mission was accomplished with high losses of 26,000 American casualties and 22,000 Japanese.[58]

The Marines played a comparatively minor role in the European theater. Nonetheless, they did continue to provide security detachments to U.S. embassies and ships, contributed personnel to small special ops teams dropped into Nazi-occupied Europe as part of Office of Strategic Services (OSS, the precursor to the CIA) missions, and acted as staff planners and trainers for U.S. Army amphibious operations, including the Normandy landings.[59][60] By the end of the war, the Corps had expanded from two brigades to six divisions, five air wings, and supporting troops, totaling about 485,000 Marines. In addition, 20 defense battalions and a parachute battalion were raised.[61] Nearly 87,000 Marines were casualties during World War II (including nearly 20,000 killed), and 82 were awarded the Medal of Honor.[62]

Photograph of the Marine Corps War Memorial, which depicts the second U.S. flag-raising atop Mount Suribachi, on Iwo Jima. The memorial is modeled on Joe Rosenthal's famous Raising the Flag on Iwo Jima.

In 1942, the Navy Seabees were created with the Marine Corps providing their organization and military training. Many Seabee units were issued the USMC standard issue and were re-designated "Marine". Despite the Corps giving them their military organization, military training, issuing them uniforms and redesignating their units, the Seabees remained Navy.[note 2][63][64] USMC historian Gordon L. Rottmann writes that one of the "Navy's biggest contributions to the Marine Corps during WWII was the creation of the Seabees."[65]

Despite Secretary of the Navy James Forrestal's prediction that the Marine flag raising at Iwo Jima meant "a Marine Corps for the next five hundred years",[66][67] the Corps faced an immediate institutional crisis following the war because of a suddenly shrunken budget. Army generals pushing for a strengthened and reorganized defense establishment attempted to fold the Marine mission and assets into the Navy and Army. Drawing on hastily assembled Congressional support, and with the assistance of the so-called "Revolt of the Admirals", the Marine Corps rebuffed such efforts to dismantle the Corps, resulting in statutory protection of the Marine Corps in the National Security Act of 1947.[68] Shortly afterward, in 1952 the Douglas–Mansfield Act afforded the commandant an equal voice with the Joint Chiefs of Staff on matters relating to the Marines and established the structure of three active divisions and air wings that remain today.

F4U Corsairs providing close air support to Marines of the 1st Marine Division fighting Chinese forces in North Korea, December 1950

The Korean War (1950–1953) saw the hastily formed Provisional Marine Brigade holding the defensive line at the Pusan Perimeter. To execute a flanking maneuver, General Douglas MacArthur called on United Nations forces, including U.S. Marines, to make an amphibious landing at Inchon. The successful landing resulted in the collapse of North Korean lines and the pursuit of North Korean forces north near the Yalu River until the entrance of the People's Republic of China into the war. Chinese troops surrounded, surprised, and overwhelmed the overextended and outnumbered American forces. The U.S. Army's X Corps, which included the 1st Marine Division and the Army's 7th Infantry Division regrouped and inflicted heavy casualties during their fighting withdrawal to the coast, known as the Battle of Chosin Reservoir.

The fighting calmed after the Battle of the Chosin Reservoir, but late in March 1953, the relative quiet of the war was broken when the People's Liberation Army launched a massive offensive on three outposts manned by the 5th Marine Regiment. These outposts were codenamed "Reno", "Vegas", and "Carson". The campaign was collectively known as the Nevada Cities Campaign. There was brutal fighting on Reno hill, which was eventually captured by the Chinese. Although Reno was lost, the 5th Marines held both Vegas and Carson through the rest of the campaign. In this one campaign, the Marines suffered approximately 1,000 casualties and might have suffered much more without the U.S. Army's Task Force Faith. Marines would continue a battle of attrition around the 38th Parallel until the 1953 armistice.[69] During the war, the Corps expanded from 75,000 regulars to a force of 261,000 Marines, mostly reservists; 30,544 Marines were killed or wounded during the war, and 42 were awarded the Medal of Honor.[70]

U.S. Marines of "G" Company, 2nd Battalion, 7th Marines in action during Operation Allen Brook in South Vietnam, 1968

The Marine Corps served in the Vietnam War, taking part in such battles as the Battle of Hue and the Battle of Khe Sanh in 1968. Individuals from the USMC generally operated in the Northern I Corps Regions of South Vietnam. While there, they were constantly engaged in a guerrilla war against the Viet Cong, along with an intermittent conventional war against the North Vietnamese Army. Portions of the Corps were responsible for the less-known Combined Action Program that implemented unconventional techniques for counter-insurgency and worked as military advisers to the Republic of Vietnam Marine Corps. Marines were withdrawn in 1971 and returned briefly in 1975 to evacuate Saigon and attempt a rescue of the crew of the SS Mayaguez.[71] Vietnam was the longest war up to that time for Marines; by its end, 13,091 had been killed in action,[72][73] 51,392 had been wounded, and 57 Medals of Honor had been awarded.[74][75] Because of policies concerning rotation, more Marines were deployed for service during Vietnam than World War II.[76]

While recovering from Vietnam, the Corps hit a detrimental low point in its service history caused by courts-martial and non-judicial punishments related partially to increased unauthorized absences and desertions during the war. Overhaul of the Corps began in the late 1970s, discharging the most delinquent, and once the quality of new recruits improved, the Corps focused on reforming the non-commissioned officer Corps, a vital functioning part of its forces.[27]

Beirut Memorial at Marine Corps Base Camp Lejeune

After the Vietnam War, the U.S. Marines resumed their expeditionary role, participating in the failed 1980 Iran hostage rescue attempt Operation Eagle Claw, the Operation Urgent Fury and the Operation Just Cause. On 23 October 1983, the Marine headquarters building in Beirut was bombed, causing the highest peacetime losses to the Corps in its history (220 Marines and 21 other service members were killed) and leading to the American withdrawal from Lebanon. In 1990, Marines of the Joint Task Force Sharp Edge saved thousands of lives by evacuating British, French and American nationals from the violence of the Liberian Civil War.

U.S. Marines from 3rd Battalion, 3rd Marines during the Desert Storm deployment in 1990–1991

During the Persian Gulf War of 1990 to 1991, Marine task forces formed for Operation Desert Shield and later liberated Kuwait, along with Coalition forces, in Operation Desert Storm.[41] Marines participated in combat operations in Somalia (1992–1995) during Operations Restore Hope, Restore Hope II, and United Shield to provide humanitarian relief.[77] In 1997, Marines took part in Operation Silver Wake, the evacuation of American citizens from the U.S. Embassy in Tirana, Albania.

U.S. Marines from 1st Battalion, 7th Marines entering a palace in Baghdad in 2003

Following the attacks on 11 September 2001, President George W. Bush announced the Global War on Terrorism. The stated objective of the Global War on Terror is "the defeat of Al-Qaeda, other terrorist groups and any nation that supports or harbors terrorists".[78] Since then, the Marine Corps, alongside the other military services, has engaged in global operations around the world in support of that mission.

U.S. Marines conducting a dawn patrol in Afghanistan's Nawa District, Helmand Province, 2010

In spring 2009, President Barack Obama's goal of reducing spending in the Defense Department was led by Secretary Robert Gates in a series of budget cuts that did not significantly change the Corps' budget and programs, cutting only the VH-71 Kestrel and resetting the VXX program.[79][80][81] However, the National Commission on Fiscal Responsibility and Reform singled the Corps out for the brunt of a series of recommended cuts in late 2010.[82] In light of budget sequestration in 2013, General James Amos set a goal of a force of 174,000 Marines.[83] He testified that this was the minimum number that would allow for an effective response to even a single contingency operation, but it would reduce the peacetime ratio of time at home bases to time deployed down to a historical low level.[84]

U.S. Marines dismounting from an Assault Amphibious Vehicle in Djibouti

Marines and other American forces began staging in Pakistan and Uzbekistan on the border of Afghanistan as early as October 2001 in preparation for Operation Enduring Freedom.[85] The 15th and 26th Marine Expeditionary Units were some of the first conventional forces into Afghanistan in support of Operation Enduring Freedom in November 2001.[86] The Marines first entered Afghanistan after Army paratroopers secured their entry.[87]

Two Marines of 3rd Battalion, 6th Marines engaging the enemy during Operation Moshtarak in Afghanistan's Helmand Province

Since then, Marine battalions and squadrons have been rotating through, engaging Taliban and Al-Qaeda forces. Marines of the 24th Marine Expeditionary Unit flooded into the Taliban-held town of Garmsir on 29 April 2008, in Helmand Province, in the first major American operation in the region in years.[88] In June 2009, 7,000 Marines with the 2nd Marine Expeditionary Brigade deployed to Afghanistan in an effort to improve security[89] and began Operation Strike of the Sword the next month. In February 2010, the 2nd Marine Expeditionary Brigade launched the largest offensive of the Afghan Campaign since 2001, the Battle of Marjah, to clear the Taliban from their key stronghold in Helmand Province.[90] After Marjah, Marines progressed north up the Helmand River and cleared the towns of Kajahki and Sangin. Marines remained in Helmand Province until 2014.

U.S. Marines served in the Iraq War, along with its sister services. The I Marine Expeditionary Force, along with the U.S. Army's 3rd Infantry Division, spearheaded the Operation Iraqi Freedom.[91] The Marines left Iraq in the summer of 2003 but returned in the beginning of 2004. They were given responsibility for the Al Anbar Province, the large desert region to the west of Baghdad. During this occupation, the Marines lead assaults on the city of Fallujah in April (Operation Vigilant Resolve) and November 2004 (Operation Phantom Fury) and saw intense fighting in such places as Ramadi, Al-Qa'im and Hīt.[92] Their time in Iraq has courted controversy with the Haditha killings and the Hamdania incident.[93][94] The Anbar Awakening and 2007 surge reduced levels of violence. The Marine Corps officially ended its role in Iraq on 23 January 2010 when they handed over responsibility for Al Anbar Province to the U.S. Army.[95] Marines returned to Iraq in the summer of 2014 in response to growing violence there.[96]

3rd Battalion, 4th Marines loading 120mm mortar rounds during Operation Inherent Resolve in Syria, 2018

Throughout the Global War on Terrorism, the U.S. Marines have supported operations in Africa to counter Islamic extremism and piracy in the Red Sea. In late 2002, Combined Joint Task Force – Horn of Africa was stood up at Camp Lemonnier, Djibouti to provide regional security.[97] Despite transferring overall command to the Navy in 2006, the Marines continued to operate in the Horn of Africa into 2007.[98]

The Department of the Navy, led by the Secretary of the Navy, is a military department of the cabinet-level U.S. Department of Defense that oversees the Marine Corps and the Navy. The most senior Marine officer is the Commandant (unless a Marine officer is the Chairman of the Joint Chiefs or Vice Chairman of the Joint Chiefs), responsible to the Secretary of the Navy for organizing, recruiting, training, and equipping the Marine Corps so that its forces are ready for deployment under the operational command of the combatant commanders. The Marine Corps is organized into four principal subdivisions: Headquarters Marine Corps (HQMC), the Operating Forces, the Supporting Establishment, and the Marine Forces Reserve (MARFORRES or USMCR).

HQMC consists of the Commandant of the Marine Corps, the Assistant Commandant of the Marine Corps, the Director Marine Corps Staff, the several Deputy Commandants, the Sergeant Major of the Marine Corps, and various special staff officers and Marine Corps agency heads that report directly to either the Commandant or Assistant Commandant. HQMC is supported by the Headquarters and Service Battalion, USMC providing administrative, supply, logistics, training, and services support to the Commandant and his staff.

The Operating Forces are divided into three categories: Marine Corps Forces (MARFOR) assigned to unified combatant commands, viz., the Fleet Marine Forces (FMF); Security Forces guarding high-risk naval installations; and Security Guard detachments at American embassies. Under the "Forces for Unified Commands" memo, in accordance with the Unified Command Plan, Marine Corps Forces are assigned to each of the combatant commands at the discretion of the secretary of defense. Since 1991, the Marine Corps has maintained component headquarters at each of the regional unified combatant commands.[99]

Marine Corps Forces are divided into Forces Command (MARFORCOM) and Pacific Command (MARFORPAC), each headed by a lieutenant general dual-posted as the commanding general of either FMF Atlantic (FMFLANT) or FMF Pacific (FMFPAC), respectively. MARFORCOM/FMFLANT has operational control of the II Marine Expeditionary Force; MARFORPAC/FMFPAC has operational control of the I Marine Expeditionary Force and III Marine Expeditionary Force.[33]

The basic framework for deployable Marine units is the Marine Air-Ground Task Force (MAGTF), a flexible structure of varying size. A MAGTF integrates a ground combat element (GCE), an aviation combat element (ACE), and a logistics combat element (LCE) under a common command element (CE), capable of operating independently or as part of a larger coalition. The MAGTF structure reflects a strong preference in the Corps towards self-sufficiency and a commitment to combined arms, both essential assets to an expeditionary force. The Marine Corps has a wariness and distrust of reliance on its sister services and towards joint operations in general.[27]

The Supporting Establishment includes the Combat Development Command, the Logistics Command, the Systems Command, the Recruiting Command, the Installations Command, the Marine Band, and the Marine Drum and Bugle Corps.

The Marine Corps operates many major bases, 14 of which host operating forces, several support and training installations, as well as satellite facilities.[100] Marine Corps bases are concentrated around the locations of the Marine Expeditionary Forces, though reserve units are scattered throughout the United States. The principal bases are Camp Pendleton on the West Coast, home to I Marine Expeditionary Force; Camp Lejeune on the East Coast, home to II Marine Expeditionary Force; and Camp Butler in Okinawa, Japan, home to III Marine Expeditionary Force.

Other important bases include air stations, recruit depots, logistics bases, and training commands. Marine Corps Air Ground Combat Center Twentynine Palms in California is the Marine Corps' largest base and home to the Corps' most complex, combined-arms, live-fire training. Marine Corps Base Quantico in Virginia is home to Marine Corps Combat Development Command and nicknamed the "Crossroads of the Marine Corps".[101][102] The Marine Corps maintains a significant presence in the National Capital Region, with Headquarters Marine Corps scattered amongst the Pentagon, Henderson Hall, Washington Navy Yard, and Marine Barracks, Washington, D.C. Additionally, Marines operate detachments at many installations owned by other branches to better share resources, such as specialty schools. Marines are also present at and operate many forward bases during expeditionary operations.

Marine Forces Reserve (MARFORRES/USMCRR) consists of the Force Headquarters Group, 4th Marine Division, 4th Marine Aircraft Wing, and the 4th Marine Logistics Group. The MARFORRES/USMCR is capable of forming a 4th Marine Expeditionary Force or reinforcing/augmenting active-duty forces.

David Berger,
Commandant of the Marine Corps

Gary L. Thomas,
Assistant Commandant of the Marine Corps

Troy E. Black,
Sergeant Major of the Marine Corps

The Commandant of the Marine Corps is the highest-ranking officer of the Marine Corps, unless a Marine is either the chairman or vice chairman of the Joint Chiefs of Staff. The commandant has the U.S. Code Title 10 responsibility to staff, train, and equip the Marine Corps and has no command authority. The commandant is a member of the Joint Chiefs of Staff and reports to the Secretary of the Navy.[106]

The Assistant Commandant of the Marine Corps acts as the chief deputy to the commandant. The Sergeant Major of the Marine Corps is the senior enlisted Marine and acts as an adviser to the commandant. Headquarters Marine Corps comprises the rest of the commandant's counsel and staff, with deputy commandants that oversee various aspects of the Corps assets and capabilities. The current and 38th Commandant is David Berger, who assumed the position on 11 July 2019.[107][108] The 35th and current Assistant Commandant is Gary L. Thomas, while the 19th and current Sergeant Major is Troy E. Black

Opha Johnson (far right) in 1946, with Katherine Towle (far left). They are looking at Opha Johnson's uniform being worn by PFC Muriel Albert.

Two of the first female graduates of the School of Infantry-East's Infantry Training Battalion course, 2013

Women have served in the United States Marine Corps since 1918.[109] The first woman to have enlisted was Opha May Johnson (1878–1955).[110][111] In January 2017, three women joined an infantry battalion at Camp Lejeune. Women had not served as infantry Marines prior to this.[112] In 2017, the Marines released a recruitment advertisement that focused on women for the first time.[113] As of October 2019, female Marines make up 7.8% of the force.

In December 2020, the Marine Corps began a trial program to have females integrated into the training companies at their recruit depot in San Diego as Congress has mandated an end to the male-only program there. For the 60 female recruits, scheduled to begin training in San Diego in February 2021, the Corps will transfer female drill instructors from their recruit depot in Parris Island, which already has a coed program.[114]

As in the rest of the United States Armed Forces (excluding the Air Force and Space Force, which do not currently appoint warrant officers), Marine Corps ranks fall into one of three categories: commissioned officer, warrant officer, and enlisted, in decreasing order of authority. To standardize compensation, each rank is assigned a pay grade.[115]

Commissioned officers are distinguished from other officers by their commission, which is the formal written authority, issued in the name of the President of the United States, that confers the rank and authority of a Marine officer. Commissioned officers carry the "special trust and confidence" of the President of the United States.[19] Marine Corps commissioned officers are promoted based on an "up or out" system in accordance with the Defense Officer Personnel Management Act of 1980.

US DoD Pay Grade	O-1	O-2	O-3	O-4	O-5	O-6	O-7	O-8	O-9	O-10
NATO Code	OF-1		OF-2	OF-3	OF-4	OF-5	OF-6	OF-7	OF-8	OF-9
Insignia
Service Dress Uniform Insignia
Title	Second lieutenant	First lieutenant	Captain	Major	Lieutenant colonel	Colonel	Brigadier general	Major general	Lieutenant general	General
Abbreviation	2ndLt	1stLt	Capt	Maj	LtCol	Col	BGen	MajGen	LtGen	Gen

Warrant officers are primarily formerly enlisted experts in a specific specialized field and provide leadership generally only within that speciality.

US DoD Pay Grade	W-1	W-2	W-3	W-4	W-5
NATO Code	WO-1	WO-2	WO-3	WO-4	WO-5
Insignia
Title	Warrant officer 1	Chief warrant officer 2	Chief warrant officer 3	Chief warrant officer 4	Chief warrant officer 5
Abbreviation	WO	CWO2	CWO3	CWO4	CWO5

Enlisted Marines in the pay grades E-1 to E-3 make up the bulk of the Corps' ranks. Although they do not technically hold leadership ranks, the Corps' ethos stresses leadership among all Marines, and junior Marines are often assigned responsibility normally reserved for superiors. Those in the pay grades of E-4 and E-5 are non-commissioned officers (NCOs).[116] They primarily supervise junior Marines and act as a vital link with the higher command structure, ensuring that orders are carried out correctly. Marines E-6 and higher are staff non-commissioned officers (SNCOs), charged with supervising NCOs and acting as enlisted advisers to the command.

The E-8 and E-9 levels have two and three ranks per pay grade, respectively, each with different responsibilities. The first sergeant and sergeant major ranks are command-oriented, serving as the senior enlisted Marines in a unit, charged to assist the commanding officer in matters of discipline, administration, and the morale and welfare of the unit. Master sergeants and master gunnery sergeants provide technical leadership as occupational specialists in their specific MOS. The Sergeant Major of the Marine Corps also E-9, is a billet conferred on the senior enlisted Marine of the entire Marine Corps, personally selected by the commandant. It is possible for an enlisted Marine to hold a position senior to Sergeant Major of the Marine Corps which was the case from 2011 to 2015 with the appointment of Sergeant Major Bryan B. Battaglia to the billet of Senior Enlisted Advisor to the Chairman, who is the most senior enlisted member of the United States military, serving in the Joint Chiefs of Staff.

US DoD Pay Grade	E-1	E-2	E-3	E-4	E-5	E-6	E-7	E-8		E-9
NATO Code	OR-1	OR-2	OR-3	OR-4	OR-5	OR-6	OR-7	OR-8		OR-9
Service Dress Uniform Insignia	No Insignia
Title	Private	Private first class	Lance corporal	Corporal	Sergeant	Staff sergeant	Gunnery sergeant	Master sergeant	First sergeant	Master gunnery sergeant	Sergeant major	Sergeant major of the Marine Corps	Senior enlisted advisor to the chairman
Abbreviation	Pvt	PFC	LCpl	Cpl	Sgt	SSgt	GySgt	MSgt	1stSgt	MGySgt	SgtMaj	SMMC	SEAC

The Military Occupational Specialty (MOS) is a system of job classification. Using a four digit code, it designates what field and specific occupation a Marine performs. Segregated between officer and enlisted, the MOS determines the staffing of a unit. Some MOSs change with rank to reflect supervisory positions; others are secondary and represent a temporary assignment outside of a Marine's normal duties or special skill.

Every year, over 2,000 new Marine officers are commissioned, and 38,000 recruits are accepted and trained.[33] All new Marines, enlisted or officer, are recruited by the Marine Corps Recruiting Command.[117]

Marine recruits at Marine Corps Recruit Depot San Diego

Commissioned officers are commissioned mainly through one of three sources: Naval Reserve Officer Training Corps, Officer Candidates School, or the United States Naval Academy. Following commissioning, all Marine commissioned officers, regardless of accession route or further training requirements, attend The Basic School at Marine Corps Base Quantico. At The Basic School, second lieutenants, warrant officers, and selected foreign officers learn the art of infantry and combined arms warfare.[19]

Marine recruits on a Squad Rush course

Enlisted Marines attend recruit training, known as boot camp, at either Marine Corps Recruit Depot San Diego or Marine Corps Recruit Depot Parris Island. Historically, the Mississippi River served as a dividing line that delineated who would be trained where, while more recently, a district system has ensured a more even distribution of male recruits between the two facilities. All recruits must pass a fitness test to start training; those who fail will receive individualized attention and training until the minimum standards are reached. Marine recruit training is the longest among the American military services; it is 13 weeks long including processing and out-processing.[118]

U.S. Marines in training

Following recruit training, enlisted Marines then attend The School of Infantry at Camp Geiger or Camp Pendleton. Infantry Marines begin their combat training, which varies in length, immediately with the Infantry Training Battalion. Marines in all other MOSs train for 29 days in Marine Combat Training, learning common infantry skills, before continuing on to their MOS schools, which vary in length.[119]

As in any military organization, the official and unofficial traditions of the Marine Corps serve to reinforce camaraderie and set the service apart from others. The Corps' embrace of its rich culture and history is cited as a reason for its high esprit de corps.[19] An important part of the Marine Corps culture is the traditional seafaring naval terminology derived from its history with the Navy. Marines are not "soldiers" or "sailors".[122]

The Eagle, Globe and Anchor along with the U.S. flag, the Marine Corps flag and the Commandant's flag

The Marine Corps emblem is the Eagle, Globe, and Anchor, sometimes abbreviated "EGA", adopted in 1868.[123] The Marine Corps seal includes the emblem, also is found on the flag of the United States Marine Corps, and establishes scarlet and gold as the official colors.[124] The Marine motto Semper Fidelis means Always Faithful in Latin, often appearing as Semper Fi. The Marines' Hymn dates back to the 19th century and is the oldest official song in the United States armed forces. Semper Fi is also the name of the official march of the Corps, composed by John Philip Sousa. The mottos "Fortitudine" (With Fortitude); By Sea and by Land, a translation of the Royal Marines' Per Mare, Per Terram; and To the Shores of Tripoli were used until 1868.[125]

Two styles of swords are worn by Marines: the officers' Mameluke Sword, similar to the Persian shamshir presented to Lt. Presley O'Bannon after the Battle of Derna, and the Marine NCO sword.[33] The Marine Corps Birthday is celebrated every year on 10 November in a cake-cutting ceremony where the first slice of cake is given to the oldest Marine present, who in turn hands it off to the youngest Marine present. The celebration includes a reading of Commandant Lejeune's Birthday Message.[126] Close Order Drill is heavily emphasized early on in a Marine's initial training, incorporated into most formal events, and is used to teach discipline by instilling habits of precision and automatic response to orders, increase the confidence of junior officers and noncommissioned officers through the exercise of command and give Marines an opportunity to handle individual weapons.[127]

A recruiting poster making use of the "Teufel Hunden" [sic] nickname

Marines have several generic nicknames:

• Devil Dog: German soldiers during the First World War said that at Belleau Wood the Marines were so vicious that the German infantrymen called them Teufel Hunden – 'devil dogs'.[128][129][130][131]
• Gyrene: commonly used between fellow Marines.[132]
• Leatherneck: refers to a leather collar formerly part of the Marine uniform during the Revolutionary War period.[133]
• Jarhead has several oft-disputed explanations.[134]

Some other unofficial traditions include mottos and exclamations:

• Oorah is common among Marines, being similar in function and purpose to the Army and Air Force's hooah and the Navy's hooyah cries. Many possible etymologies have been offered for the term.[135]
• Semper Fi is a common greeting among serving and veteran Marines.
• Improvise, Adapt and Overcome has become an adopted mantra in many units.[136]

The Corps encourages the idea that "Marine" is an earned title, and most Marine Corps personnel take to heart the phrase "Once a Marine, Always a Marine". They reject the term "ex-Marine" in most circumstances. There are no regulations concerning the address of persons who have left active service, so a number of customary terms have come into common use.[68]

An honorably discharged Marine is a "Marine". The title "Marine Corps Veteran" is also acceptable. There are no honorably discharged "Former" or "Ex" Marines. "Retired Marine" is generally reserved for those who have completed 20 or more years of service are called "Lifers" and formally retired or those who have been medically retired. According to one of the "Commandant's White letters" from Commandant Alfred M. Gray, Jr., referring to a Marine by their last earned rank is appropriate.[137]

Marines training in martial arts

In 2001, the Marine Corps initiated an internally designed martial arts program, called Marine Corps Martial Arts Program (MCMAP). Because of an expectation that urban and police-type peacekeeping missions would become more common in the 21st century, placing Marines in even closer contact with unarmed civilians, MCMAP was implemented to provide Marines with a larger and more versatile set of less-than-lethal options for controlling hostile, unarmed individuals. It is a stated aim of the program to instill and maintain the "Warrior Ethos" within Marines.[138] The MCMAP is an eclectic mix of different styles of martial arts melded together. MCMAP consists of punches and kicks from Taekwondo and Karate, opponent weight transfer from Jujitsu, ground grappling involving joint locking techniques and chokes from Brazilian jiu-jitsu, and a mix of knife and baton/stick fighting derived from Eskrima, and elbow strikes and kick boxing from Muay Thai. Marines begin MCMAP training in boot camp, where they will earn the first of five available belts.The belts begin at tan and progress to black and are worn with standard utility uniforms.[139]

Marines firing MEU(SOC) pistols while garrisoned aboard a ship

The basic infantry weapon of the Marine Corps has been M16A4 service rifle. Most non-infantry Marines have been equipped with the M4 Carbine[141] and Colt 9mm SMG.[142] The standard side arm is the M9A1 pistol. The Colt M1911 is also being put back into service as the M45A1 Close Quarter Battle Pistol (CQBP) in small numbers. Suppressive fire is provided by the M27 IAR, M249 SAW, and M240 machine guns, at the squad and company levels respectively. In 2018, the M27 IAR was selected to be the standard issue rifle for the Corps.

Indirect fire is provided by the M203 grenade launcher and the M32 grenade launcher in fireteams, M224 60 mm mortar in companies, and M252 81 mm mortar in battalions. The M2 .50 caliber heavy machine gun and MK19 automatic grenade launcher (40 mm) are available for use by dismounted infantry, though they are more commonly vehicle-mounted. Precision firepower is provided by the M40 series and the Barrett M107, while designated marksmen use the DMR (being replaced by the M39 EMR), and the SAM-R.[143]

Marine Amphibious Assault Vehicles emerge from the surf onto the sand of Freshwater Beach, Australia

The Marine Corps utilizes a variety of direct-fire rockets and missiles to provide infantry with an offensive and defensive anti-armor capability. The SMAW and AT4 are unguided rockets that can destroy armor and fixed defenses (e.g., bunkers) at ranges up to 500 meters. The smaller and lighter M72 LAW can destroy targets at ranges up to 200 meters.[144][145] The Predator SRAW, FGM-148 Javelin and BGM-71 TOW are anti-tank guided missiles. The Javelin can utilize top-attack profiles to avoid heavy frontal armor. The Predator is a short-range fire-and-forget weapon; the Javelin and TOW are heavier missiles effective past 2,000 meters that give infantry an offensive capability against armor.[146]

The USMC is currently seeking to purchase commercial off-the-shelf bullet-trap or shoot-through rifle-grenades.[147] These grenades will provide individual Marines additional firepower and will allow indirect fire against targets in defilade, behind walls and buildings or rooftops and elevated positions at ranges between 30 and 150 meters.[147]

The Corps operates the same HMMWV as does the Army. However, for its specific needs, the Corps uses a number of unique vehicles. The LAV-25 is a dedicated wheeled armored personnel carrier, similar to the Army's Stryker vehicle, used to provide strategic mobility.[148] Amphibious capability is provided by the AAV-7A1 Assault Amphibious Vehicle, an armored tracked vehicle that doubles as an armored personnel carrier, due to be replaced by the Amphibious Combat Vehicle, a faster vehicle with superior armor and weaponry. The threat of land mines and improvised explosive devices in Iraq and Afghanistan has seen the Corps begin purchasing heavy armored vehicles that can better withstand the effects of these weapons as part of the Mine Resistant Ambush Protected vehicle program.[149] [150]

The Marines operate the M777 155 mm howitzer, including the High Mobility Artillery Rocket System (HIMARS), a truck-mounted rocket artillery system. Both are capable of firing guided munitions.[151] In 2020, the Marine Corps retired its M1A1 Abrams tanks and eliminated all of its tank units. General David Berger explained the decision describing the long-serving Marine weapons system as "operationally unsuitable for our highest-priority challenges." The move leaves the Army as the sole operator of American tanks.[152]

Marine parachutists jumping from an MV-22 Osprey at 10,000 feet

The organic aviation capability of the Marine Corps is essential to its amphibious mission. The Corps operates both rotary-wing and fixed-wing aircraft mainly to provide Assault Support and close air support to its ground forces. Other aircraft types are used in a variety of support and special-purpose roles. The light transport and attack capabilities are provided by the Bell UH-1Y Venom and Bell AH-1Z Viper.[153] Medium-lift squadrons utilize the MV-22 Osprey tiltrotor. Heavy-lift squadrons are equipped with the CH-53E Super Stallion helicopter, which are being replaced with the upgraded CH-53K.[154]

A Marine AH-1Z Viper landing on USS Makin Island in 2010

Marine attack squadrons fly the AV-8B Harrier II; while the fighter/attack mission is handled by the single-seat and dual-seat versions of the F/A-18 Hornet strike-fighter aircraft. The AV-8B is a V/STOL aircraft that can operate from amphibious assault ships, land air bases and short, expeditionary airfields, while the F/A-18 can only be flown from land or aircraft carriers. Both are slated to be replaced by 340 of the STOVL B version of the F-35 Lightning II[155] and 80 of the carrier F-35C versions for deployment with Navy carrier air wings.[156][157][158][159]

A Marine Corps F-35B, the vertical-landing version of the F-35 Lightning II multirole fighter landing aboard USS Wasp

The Corps operates its own organic aerial refueling assets in the form of the KC-130 Hercules; however it also receives a large amount of support from the U.S. Air Force. The Hercules doubles as a ground refueler and tactical-airlift transport aircraft. The USMC electronic warfare plane, the EA-6B, was retired in 2019. The Marines operate unmanned aerial vehicles: the RQ-7 Shadow and Scan Eagle for tactical reconnaissance.[160][161]

Marine Fighter Training Squadron 401 (VMFT-401), operates F-5E, F-5F and F-5N Tiger II aircraft in support of air combat adversary (aggressor) training. Marine Helicopter Squadron One (HMX-1) operates the VH-3D Sea King and VH-60N Whitehawk helicopters in the VIP transport role, most notably Marine One, but are due to be replaced. A single Marine Corps C-130 Hercules aircraft, "Fat Albert", is used to support the U.S. Navy's flight demonstration team, the "Blue Angels".

McDonnell Douglas F/A-18 Hornet of Marine Fighter Attack Squadron 212 (VMFA-212) over the South China Sea

Assault Amphibious Vehicles approaching the well deck of USS Bonhomme Richard

The Marine Corps's counterpart under the Department of the Navy is the United States Navy. As a result, the Navy and Marine Corps have a close relationship, more so than with other branches of the military. Whitepapers and promotional literature have commonly used the phrase "Navy-Marine Corps Team",[162][163] or refer to "the Naval Service". Both the Chief of Naval Operations (CNO) and Commandant of the Marine Corps report directly to the Secretary of the Navy.

Operationally, the Marine Corps provides the Fleet Marine Forces for service with the Navy's fleets, including the forward-deployed Marine Expeditionary Units embarked aboard Navy amphibious warships. The Corps also contributes some Marine Aviation fixed-wing fighter/attack assets (aircraft squadrons and related aircraft maintenance augmentation units) as part of the Carrier Air Wings deployed aboard aircraft carriers. The Marine Corps Security Force Regiment provides infantry-based security battalions and Fleet Anti-terrorism Security Team companies to guard and defend high-priority and overseas Navy bases. Security for the Presidential Retreat located aboard the Naval Support Activity Thurmont, viz., Camp David is provided by the Marine infantry battalion stationed as part of the garrison aboard Marine Barracks Washington.

Cooperation between the two services includes the training and instruction of some future Marine Corps officers (most are trained and commissioned through Marine Corps OCS), all Marine Corps Naval Aviators (aircraft pilots) and Naval Flight Officers (airborne weapons and sensor system officers), and some Navy and Marine Corps enlisted personnel. The Corps receives a significant portion of its officers from the United States Naval Academy (USNA) and Naval Reserve Officers Training Corps (NROTC). USNA and NROTC staff and faculty includes Marine Corps instructors. Marine Corps aviators and flight officers are trained in the Naval Air Training Command (NATRACOM) and are designated, or winged as Naval Aviators or Naval Flight Officers. The Marine Corps provides flight instructors to the Naval Air Training Command as well as drill instructors to the Navy's Officer Candidate School. Many enlisted Marines, particularly those in the aviation maintenance specialties, are trained at Navy technical training centers. The Marine Corps also provides ground combat training support to various Navy field medical (Hospital Corpsmen), Naval Construction Force (Seabee), and Navy Expeditionary Warfare personnel, units, and commands.

A Marine and sailor training with rifles in Iraq

Training alongside each other is viewed as critical, as the Navy provides transport, logistical, and combat support to put Marine units into the fight, such as maritime prepositioning ships and naval gunfire support. Most Marine aviation assets ultimately derive from the Navy, with regard to acquisition, funding, and testing, and Navy aircraft carriers typically deploy with a Marine squadron alongside Navy squadrons. Marines do not recruit or train noncombatants such as chaplains or medical/dental personnel; naval personnel fill these roles. Some of these sailors, particularly Hospital corpsmen and Religious program specialists, generally wear Marine uniforms emblazoned with Navy insignia. Conversely, the Marine Corps is responsible for conducting land operations to support naval campaigns, including the seizure of naval bases. Both services operate a network security team in conjunction.

Marines and sailors share many naval traditions, especially terminology and customs. Marine Corps Medal of Honor recipients wear the Navy variant of this and other awards;[24] and with few exceptions, the awards and badges of the Navy and Marine Corps are identical. Much of testing for new Marine Corps aircraft is done at Naval Air Station Patuxent River. The Navy's Blue Angels flight demonstration team is staffed by both Navy and Marine officers and enlisted men.[24]

In 2007, the Marine Corps joined with the Navy and Coast Guard to adopt a new maritime strategy called A Cooperative Strategy for 21st Century Seapower that raises the notion of prevention of war to the same philosophical level as the conduct of war.[164] This new strategy charts a course for the Navy, Coast Guard and Marine Corps to work collectively with each other and international partners to prevent regional crises, man-made or natural, from occurring or reacting quickly should one occur to avoid negative impacts to the United States.

A soldier from the 1st Infantry Regiment provides security for a joint Army-Marine patrol in Rawa in 2006. The shoulder sleeve insignia has the logo of the 2nd Marine Division.

The Marine Corps combat capabilities overlap with those of the United States Army, the latter having historically viewed the Corps as encroaching on the Army's capabilities and competing for funding, missions, and renown. The attitude dates back to the founding of the Continental Marines, when General George Washington refused to allow the initial Marine battalions to be drawn from among his Continental Army. Most significantly, in the aftermath of World War II, Army efforts to restructure the American defense establishment included the dissolution of the Corps and the folding of its capabilities into the other services. Leading this movement were such prominent Army officers as General Dwight D. Eisenhower and Army Chief of Staff George C. Marshall.[68] Nonetheless, during the Korean War, the Marines received the admiration of such Army officers as General Douglas MacArthur and Major General Frank E. Lowe. More recently, with most of the 2000s spent in operations in Afghanistan and Iraq, Secretary of Defense Robert Gates voiced concerns that the Marines are becoming a "second Army".[31]

Doctrinally, the Marine Corps' focus is on being expeditionary and independent, and places emphasis on amphibious mobility and combined arms; these make it a much lighter force than many units of the Army. However, the Army maintains much larger and diverse combat arms (infantry, armor, artillery, special operations), ground transport, and logistics, while the Marines have a more diverse aviation arm (which constitutes a larger percentage of forces) and is usually organic to the MAGTF. Marines operate as expeditionary units and are completely amphibious. The Marine Corps focus is on standardized infantry units with the other arms in support roles, as the "Every Marine a rifleman" creed shows. This commitment to standardized units can be seen in the short-lived experiment of the Marine Raiders. Widely known as the first American special operations unit, created during World War II (February 1941[165]), was seen as controversial, because the thought of ‘an elite unit, within an elite unit’ was not in the Marine Corps interest.[166] While the U.S. Army's 75th Ranger Regiment, also created in World War II (December 1941), enjoys high prestige to this day because of its continuous service. In2003 the Marine Corps, by the insistence of Secretary of Defense Donald Rumsfeld,[167] were to create the present-day successors to the Marine Raiders and join them to Special Operations Command starting with the establishment of MCSOCOM Detachment One.[104]

Culturally, Marines and soldiers share most of the common U.S. military slang and terminology, but the Corps utilizes a large number of naval terms and traditions incompatible with army lifestyle, as well as their own unique vernacular. Many Marines regard their culture to have a deep warrior tradition, with the ethos that "Every Marine a rifleman" and emphasis on cross-training and combat readiness despite the actual military occupation, be it infantry or otherwise. Doctrinally, Marines tend to decentralize and push leadership to lower ranks, while fostering initiative to a greater degree.[168]

Marines unloading CH-46 Sea Knight helicopters from an Air Force C-5 Galaxy

While some of Marine Corps Aviation assets ultimately derive from the Navy, a large amount of support is drawn from the United States Air Force. The Marine Corps makes extensive use of the USAF Air Mobility Command to airlift Marines and equipment, along with utilizing close air support from the Air Force. The Air Force may also attach Tactical Air Control Party units to conventional Marine ground forces to provide coordination for close air support.[169]

The Air Force traditionally provides the Joint Force Air Component Commander (JFACC) who controls "sorties for air defense, and long range interdiction and reconnaissance" while the MAGTF commander retains control of the Marines' organic aviation assets, however Marine Aviation missions not directly in the support of the MAGTF will be typically controlled by the JFACC.[170][171][172]

The Marine Corps shares a sphere of operation with units of the United States Coast Guard, including operation of the Joint Maritime Training Center (JMTC) (previously known as the Special Missions Training Center (SMTC)), a joint Coast Guard, Navy, and Marine Corps training facility located on the Marine Corps Base Camp Lejeune in Camp Lejeune, North Carolina.