John was born on the 11th of October, 1871, in Haverhill, Massachusetts with the birth name of George. He enlisted in the US Marine Corps under the name of John Adams and when he deployed to China in support of the Boxer Rebellion, he was a Sergeant when he displayed actions that would earn him the Medal of Honor. The citation reads:

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

John received his Medal of Honor one year later on the 19th of July, 1901, and reenlisted when he was in Panama on the 11th of October, 1902. The following year, he was promoted to Gunnery Sergeant. George Lawrence Day, also known as John Mapes Adams, died on the 6th of January, 1921, at the age of 49 and is buried in the Cypress Hills National Cemetery in Brooklyn, New York: Section 2, Grave 8262.