United States Marine Corps

===American Civil War to World War I===
[[File:Marines01.jpg|thumb|Five USMC privates with fixed [[bayonet]]s, and their NCO with his sword at the [[Washington Navy Yard]], 1864|alt=black & white photograph of six U.S. marines standing in line, five with Civil War-era rifles and one with an NCO sword.]]

The Marine Corps played a small role in the [[American Civil War|Civil War]] (1861–1865); their most prominent task was [[blockade]] duty. As more and more states [[Ordinance of Secession|seceded]] from the [[Union (American Civil War)|Union]], about a third of the Corps's officers left the United States to join the [[Confederate States of America|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.<ref name="ChenowethNihart"/> 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|1861|6}} 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 [[Siege of Fort Pulaski|bombardment of Fort Pulaski]].<ref>{{cite web|url=http://shapiro.anthro.uga.edu/Lamar/images/PDFs/publication_127.pdf |title=Archaeological Reconnaissance at the Drudi Tract, Tybee Island, Chatham County, Georgia |publisher=LAMAR Institute Publication Series |first=Daniel T. |last=Elliott |location=Savannah, Georgia |year=2008 |page=9 |access-date=7 October 2011 |url-status=dead |archive-url=https://web.archive.org/web/20111001013945/http://shapiro.anthro.uga.edu/Lamar/images/PDFs/publication_127.pdf |archive-date=1 October 2011}}</ref> In April and May 1862, Marines participated in [[Capture of New Orleans|the capture and occupation of New Orleans]] and the occupation of Baton Rouge, Louisiana,<ref>Hoffman, Colonel Jon T., ''USMC: A Complete History'', Marine Corps Association, Quantico, VA, (2002), p. 92.</ref> 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 of the United States|Gulf Coast]].{{Citation needed|date=March 2021}}

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 [[sailing ship|sail]] to [[steamboat|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 the 19th century.<ref>{{cite web|url=http://www.mcu.usmc.mil/historydivision/pages/frequently_requested/Casualties.aspx|title=Marine Corps Casualties: 1775–2015|work=Frequently Requested|author=Reference Branch|publisher=USMC History Division|year=2016|access-date=23 April 2016|url-status=dead|archive-url=https://web.archive.org/web/20160426035939/http://www.mcu.usmc.mil/historydivision/pages/frequently_requested/Casualties.aspx|archive-date=26 April 2016}}</ref> They were called upon to stem political and labor unrest within the United States.<ref name="Ellsworth">{{Cite book |last= Ellsworth |first= Harry Allanson |title= One Hundred Eighty Landings of United States Marines 1800–1934 |publisher= History and Museums Division, HQ, USMC |year= 1934 |location= Washington, D.C.}}</ref> Under Commandant [[Jacob Zeilin]]'s tenure, Marine customs and traditions took shape: the Corps adopted the [[Eagle, Globe, and Anchor|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'').<ref name="Simmons" /> [[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 [[United States Marine Band|Marine Band]].<ref>{{Cite web |title=John Philip Sousa |url=https://www.marineband.marines.mil/About/Our-History/John-Philip-Sousa/ |access-date=2023-12-16 |website=www.marineband.marines.mil}}</ref>

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 [[Guantanamo Bay Naval Base|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 affair|Perdicaris incident]] in Morocco, [[United States occupation of Veracruz|Veracruz]], [[Santo Domingo]], and the [[Banana Wars]] in [[United States occupation of Haiti|Haiti]] and [[United States occupation of Nicaragua|Nicaragua]];{{Citation needed|date=March 2021}} the experiences gained in counterinsurgency and [[Guerrilla warfare|guerrilla operations]] during this period were consolidated into the ''Small Wars Manual''.<ref>{{Cite report|title=Report on Marine Corps Duplication of Effort between Army and Navy |publisher= U.S. Marine Corps |date= 17 December 1932}} Contains a very detailed account of almost all the actions of the Continental Marines and USMC until 1932. It is available in scanned TIFF format from the archives of the Marine Corps University.</ref>{{Better source needed|date=March 2021}}