John Coleman was born on October 9, 1847, in County Cork, Ireland, and later immigrated to the United States. He enlisted in the U.S. Marine Corps on January 26, 1870, in Brooklyn, New York, and served aboard the steam screw frigate USS Colorado during the Korean Expedition in 1871. Then Private Coleman was awarded the Medal of Honor on February 8, 1872, for his actions aboard the USS Colorado during the Battle of Ganghwa in June 1871. He retired from the Marine Corps on August 31, 1893, and died on October 30, 1904.

His Medal of Honor Citation reads:

On board the U.S.S. COLORADO in action at Korea on 11 June 1871. Fighting hand-to-hand with the enemy, COLEMAN succeeded in saving the life of Alexander McKenzie.