Born ca. 1846 in Waukesha, Wisconsin
Committed suicide at Columbia Barracks, Ohio.
Enlised 17 April 1871 in the 7th U.S. Cavalry. Was a corpral in Co. F commanded by George Yates at the time of the Battle of the Little Big Horn. Rankin was on detached duty at Powder River Depot.
Prior to enlisting in the 7th he had been a farmer. He had a wife named Mary and two sons.