United States Marine Corps

===United States Army===
[[File:CSA-2006-01-12-095303 M249SAW.jpg|thumb|A soldier from the [[1st Infantry Regiment (United States)|1st Infantry Regiment]] provides security for a joint Army-Marine patrol in [[Rawa (Iraq)|Rawa]] in 2006. The [[shoulder sleeve insignia]] has the logo of the [[2nd Marine Division (United States)|2nd Marine Division]].]]

The Marine Corps capabilities overlap with those of the United States Army, historically creating competition for funding and missions. The competition 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. In the aftermath of World War II, Army leadership made efforts to restructure the American defense establishment including the dissolution of the Marine 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 [[Chief of Staff of the United States Army|Army Chief of Staff]] [[George C. Marshall]].<ref name="Krulak"/> The [[Goldwater-Nichols Act]] significantly reshaped the services roles and relationships with each other, enforcing more joint decision making.<ref>{{cite web|title=Goldwater-Nichols Act |url=https://history.defense.gov/Portals/70/Documents/dod_reforms/Goldwater-NicholsDoDReordAct1986.pdf|website=DOD|accessdate=30 December 2021}}</ref> Department of Defense Directive 5100.01 tasks both the Army and Marine Corps with expeditionary and amphibious operations.<ref>{{cite web|title=DODD 5100.01 |url=https://www.esd.whs.mil/Portals/54/Documents/DD/issuances/dodd/510001p.pdf|website=DOD|accessdate=30 December 2021}}</ref> With most of the 2000s spent in operations in Afghanistan and Iraq, Secretary of Defense [[Robert Gates]] voiced concerns that the Marine Corps are becoming a "second Army".<ref name="2ndarmy">{{cite web |author=Kevin Baron |title=Gates: Time has come to re-examine future of Marine Corps |date=12 August 2010 |url=http://www.stripes.com/news/gates-time-has-come-to-re-examine-future-of-marine-corps-1.114465 |access-date=20 September 2010 |archive-url=https://web.archive.org/web/20100916071214/http://www.stripes.com/news/gates-time-has-come-to-re-examine-future-of-marine-corps-1.114465 |archive-date=16 September 2010 |url-status=live}}</ref> Since these comments, the Marine Corps has shed its main battle tanks, reduced its size, and focused more on operations in littoral areas where the Army is not explicitly tasked to operate.<ref>{{cite web|title=Marine Corps Restructure |url=https://www.businessinsider.com/marines-are-joining-the-army-as-corps-sheds-tank-battalions-2021-4|website=Business Insider|accessdate=30 December 2021}}</ref>

The Army maintains much larger and diverse combat arms, special operations, and logistics forces. The Army has much lighter and expeditionary forces in its infantry and airborne infantry brigade combat teams. The Army also maintains heavier and more logistically taxing armored brigade combat teams.<ref>{{cite web|title=FM 3–96|url=https://armypubs.army.mil/epubs/DR_pubs/DR_a/ARN31505-FM_3-96-000-WEB-1.pdf|website=DA Pubs|accessdate=30 December 2021}}</ref> The Marine Corps, in comparison, maintains forces between these two extremes of mobility and protection. The Marine Corps organizes much smaller deployable units with integrated aviation support. The Marine Corps was historically hesitant to provide forces to U.S. Special Operations Command, instead making specialty units available to its division commanders. The Army has maintained Special Forces, Rangers, civil affairs, psychological operations, special operations aviation, and special missions units for decades. In 2003, the Marine Corps<ref name="Donald Rumsfeld">{{cite news |author= Bradley Graham |title= Elite Marine Unit to Help Fight Terrorism |newspaper= [[The Washington Post]] |date= 3 November 2005 |url= https://www.washingtonpost.com/wp-dyn/content/article/2005/11/01/AR2005110102069.html |access-date= 17 September 2017 |archive-url= https://web.archive.org/web/20170525191505/http://www.washingtonpost.com/wp-dyn/content/article/2005/11/01/AR2005110102069.html |archive-date= 25 May 2017 |url-status=live |df= dmy-all}}</ref> created the present-day successors to the [[Marine Raiders]] and provided them to [[United States Special Operations Command|Special Operations Command]] starting with the establishment of [[Det One|MCSOCOM Detachment One]]. The modern Marine Raider training pipeline was based on input from U.S. Army Ranger and Special Forces units.<ref name="Priddy">{{cite news|last= Priddy |first= Maj. Wade |title= Marine Detachment 1: Opening the door for a Marine force contribution to USSOCom |journal=Marine Corps Gazette |volume= 90|issue=6 |pages= 58–59 |publisher=Marine Corps Association |year= 2006}}</ref>

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 its own [[List of United States Marine Corps acronyms and expressions|unique vernacular]]. As the Army Reserve and Army National Guard is much larger than the Marine Corps's Reserve, many more former active duty marines continue their service in the Army's reserve components.<ref>{{cite web|title=Marine to Guard|url=https://www.nationalguard.com/m2gl|website=National Guard|accessdate=30 December 2021}}</ref> The Army does not require transfers from the Marines, [[Air Force Security Forces]], or special operations of any branch to attend Army Basic Combat Training.<ref>{{cite web|title=Go Army|url=https://www.goarmy.com/careers-and-jobs/current-and-prior-service/continue-serving/transitioning-services/inter-service-transfer-program.m.html|website=Go Army|accessdate=30 December 2021}}</ref> Due to the requirement that all inter-service transfers attend Marine Corps Recruit Training, very few former soldiers serve in the Marine Corps.