John Loomis Chamberlain (January 20, 1858 – November 14, 1948) was career officer in the United States Army.

[1] He served at Fort Alcatraz, California from November 1881 to December 1882, when he began attendance at the Willets Point, New York Torpedo School.

[1][b] Chamberlain served again at Fort Alcatraz from June to October 1883, then was posted to the Presidio of San Francisco, where he remained until July 1884.

[1] He was then assigned to the Washington Navy Yard, where John T. Thompson and he studied and experimented with artillery design and construction.

[1] He was then assigned to Battery D, 1st Artillery and served at Fort Sheridan, Illinois and Washington Barracks, District of Columbia from October 1896 to July 1897.

[1] During the Spanish–American War, Chamberlain returned to the United States and performed recruiting in New York City from June to July 1898.

[1] In July, he was promoted to temporary major and assigned as adjutant and ordnance officer for the Siege Artillery Train organized in Tampa, Florida and intended for service in Cuba.

[1] From January to March 1912, Chamberlain attended a special course at the Fort Leavenworth, Kansas School of the Line (now the United States Army Command and General Staff College.

[1] From June to October 1920, Chamberlain served in Europe, where he performed post-war inspector general duties for American Forces in Germany, graves registration, and other activities within the purview of the United States Department of War.

[1] From July to November 1921, Chamberlain was on an extended leave of absence while he conducted observation tours of several countries on behalf of the War Department, including all of the Balkan States, Turkey, Syria, Palestine, and Egypt.

[1] He was awarded the Army Distinguished Service Medal, the citation for which reads: The President of the United States of America, authorized by Act of Congress, July 9, 1918, takes pleasure in presenting the Army Distinguished Service Medal to Major General John Loomis Chamberlain, United States Army, for exceptionally meritorious and distinguished services to the Government of the United States, in a duty of great responsibility during World War I.