John Mapes Adams (October 11, 1871 – January 6, 1921) was an American Marine who received the Medal of Honor for valor during the Boxer Rebellion.

[1] His birth name was George Lawrence Day, but he served in the Marine Corps under the alias of John Mapes Adams.

[3] On July 13, 1900, while a sergeant in the United States Marine Corps he "distinguished himself by meritorious conduct" in battle at Tianjin, China (then Tientsin).

As of May 20, 1903 he had been promoted to the rank of gunnery sergeant and was hospitalized in Washington, D.C.[4] Adams was buried at the Cypress Hills National Cemetery in Brooklyn, New York.

Citation: In the presence of the enemy during the battle near Tientsin, China, 13 July 1900, Adams distinguished himself by meritorious conduct.