United States Navy

===Relationships with other service branches===
====United States Marine Corps====
{{main|United States Marine Corps}}
[[File:F-18A Hornet VMFA-451 USS Coral Sea 1989.jpeg|thumb|A [[United States Marine Corps|Marine]] [[F/A-18]] from [[VMFA-451]] preparing to launch from {{USS|Coral Sea|CV-43|6}}]]

In 1834, the [[United States Marine Corps]] came under the Department of the Navy.<ref>{{cite web |url=http://www.lejeune.usmc.mil/2dfssg/med/files/102.htm |title=Navy and Marine Corps History, Customs, and Courtesies – Fundamentals |website=[[Marine Corps Base Camp Lejeune]] |publisher=[[United States Marine Corps]] |archive-url=https://web.archive.org/web/20120314062316/http://www.lejeune.usmc.mil/2dfssg/med/files/102.htm |archive-date=14 March 2012}}</ref> Historically, the Navy has had a unique relationship with the USMC, partly because they both specialize in seaborne operations. Together the Navy and Marine Corps form the Department of the Navy and report to the Secretary of the Navy. However, the Marine Corps is a distinct, separate service branch<ref name=NSA1947sec606>{{cite web |url=http://global.oup.com/us/companion.websites/9780195385168/resources/chapter10/nsa/nsa.pdf |title=National Security Act of 1947 (As amended 3 August 2007), (50 U.S.C. 426) |date=26 July 1947 |at=§606.(9) p. 69 |access-date=20 June 2015 |archive-url=https://web.archive.org/web/20150213062458/http://global.oup.com/us/companion.websites/9780195385168/resources/chapter10/nsa/nsa.pdf |archive-date=13 February 2015 |url-status=live}}</ref> with its own uniformed service chief – the Commandant of the Marine Corps, a four-star general.

The Marine Corps depends on the Navy for medical support (dentists, [[Medical doctor|doctors]], nurses, medical technicians known as [[Hospital corpsman|corpsmen]]) and religious support (chaplains). Thus, Navy officers and enlisted sailors fulfill these roles. When attached to Marine Corps units deployed to an operational environment they generally wear Marine camouflage uniforms, but otherwise, they wear Navy [[dress uniform]]s unless they opt to conform to Marine Corps grooming standards.<ref name=":0" />

In the operational environment, as an expeditionary force specializing in amphibious operations, Marines often embark on Navy ships to conduct operations from beyond territorial waters. Marine units deploying as part of a Marine Air-Ground Task Force (MAGTF) operate under the command of the existing Marine chain of command. Although Marine units routinely operate from amphibious assault ships, the relationship has evolved over the years much as the Commander of the Carrier Air Group/Wing (CAG) does not work for the carrier commanding officer, but coordinates with the ship's CO and staff. Some Marine aviation squadrons, usually fixed-wing assigned to carrier air wings train and operate alongside Navy squadrons; they fly similar missions and often fly sorties together under the cognizance of the CAG. Aviation is where the Navy and Marines share the most common ground since aircrews are guided in their use of aircraft by standard procedures outlined in a series of publications known as [[NATOPS]] manuals.

====United States Coast Guard====
{{main|United States Coast Guard}}
[[File:Flickr - Official U.S. Navy Imagery - U.S. Coast Guard helicopters land aboard USS Wasp..jpg|thumb|right|A U.S. Coast Guard helicopter preparing to land on the flight deck of the amphibious assault ship {{USS|Wasp|LHD-1|6}}]]

The [[United States Coast Guard]], in its peacetime role with the [[Department of Homeland Security]], fulfills its law enforcement and rescue role in the maritime environment. It provides [[Law Enforcement Detachments]] (LEDETs) to Navy vessels, where they perform arrests and other law enforcement duties during naval boarding and interdiction missions. In times of war, the Coast Guard may be called upon to operate as a service in the Navy.<ref>{{cite web |url=https://www.law.cornell.edu/uscode/text/14/3- |website=[[Legal Information Institute]] |publisher=[[Cornell University Law School]] |title=14 USC 3. Relationship to Navy Department |access-date=28 July 2013}}</ref> At other times, Coast Guard [[Port Security Unit]]s are sent overseas to guard the security of ports and other assets. The Coast Guard also jointly staffs the Navy's naval coastal warfare groups and squadrons (the latter of which were known as harbor defense commands until late-2004), which oversee defense efforts in foreign littoral combat and inshore areas.