United States Marine Corps

===World War I===
[[File:Scott Belleau Wood.jpg|thumb|alt=monochromatic artwork of marines fighting Germans in a forest|Georges Scott, [[Battle of Belleau Wood|''American Marines in Belleau Wood'']], 1918]]

During [[World War I]], Marines served as a part of the [[American Expeditionary Forces|American Expeditionary Force]] under General [[John J. Pershing]] when [[American entry into World War I|America entered into the war]] on 6 April 1917. The Marine Corps had a deep pool of officers and [[non-commissioned officer]]s 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.<ref>{{cite web|title=History of Marine Corps Aviation – World War One |publisher=AcePilots.com |url=http://www.acepilots.com/usmc/hist2.html |url-status=dead |archive-url=https://web.archive.org/web/20060111063805/http://www.acepilots.com/usmc/hist2.html |archive-date=11 January 2006}}</ref> African-Americans were entirely excluded from the Marine Corps during this conflict.<ref>Chad L. Williams, ''Torchbearers of Democracy: African American Soldiers in the World War I Era.'' Chapel Hill, North Carolina: University of North Carolina Press, 2010; p. 6.</ref> [[Opha May Johnson]] was the first woman to enlist in the Marines; she joined the [[Marine Forces Reserve|Marine Corps Reserve]] in 1918 during World War I, officially becoming the first female Marine.<ref name="History">{{cite book|last=Hewitt|first=Linda J.|title=Women Marines in World War I (1974)|year=1974|publisher=United States Marine Corps History and Museums Division|url=https://archive.org/details/WomenMarinesInWorldWarI|access-date=31 December 2014|archive-url=https://web.archive.org/web/20160315070622/https://archive.org/details/WomenMarinesInWorldWarI|archive-date=15 March 2016|url-status=live}}</ref> From then until the end of World War I, 305 women enlisted in the Corps.<ref>{{cite web |url=http://www.usmcpress.com/heritage/women_marines.htm |title=Women Marines |publisher=Usmcpress.com |access-date=11 August 2015 |archive-url=https://web.archive.org/web/20150819072746/http://www.usmcpress.com/heritage/women_marines.htm |archive-date=19 August 2015 |url-status=live}}</ref> During the [[Battle of Belleau Wood]] in 1918, the Marines and U.S. media reported that Germans had nicknamed them ''<!--Do not use a spell checker here-->Teufel Hunden,<!--Look at the hyperlink, before correcting the word, it is supposed to be misspelled--->'' meaning "[[Devil Dog]]s" 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.<ref>{{cite magazine |magazine=Life |title=Teufel-Hunden |year=1918 |first=John Ames |last=Mitchell |volume=72 |url=https://books.google.com/books?id=qahGAQAAIAAJ&pg=PA759 |page=759 |access-date=7 October 2011 |archive-date=26 October 2021 |archive-url=https://web.archive.org/web/20211026212033/https://books.google.com/books?id=qahGAQAAIAAJ&pg=PA759 |url-status=live }}</ref>

[[Interwar period|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 Ellis|Earl Hancock "Pete" Ellis]], foresaw a war in the Pacific with [[Empire of Japan|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.<ref name="Ballendorf">{{Cite book
 |last= Ballendorf
 |first= Dirk Anthony
 |title= Pete Ellis: an amphibious warfare prophet, 1880–1923
 |publisher= Naval Institute Press
 |year= 1997
 |location= Annapolis, Maryland
}}</ref>