A civilian contractor, Custer served as forage master for his brother George's U.S. 7th Cavalry Regiment in the 1874 Black Hills expedition.

Hearing from a messenger that Lt. Col. Custer had requested ammunition for an impending fight, they quickly left the pack train.

The pair passed by Frederick Benteen's detachment and joined Custer's main column as it moved into position to attack a sprawling Indian village along the Little Bighorn River.

Though originally buried on the battlefield, Autie Reed and Boston Custer's remains were exhumed, the only exceptions to the rule that only commissioned officers would be shipped home for reburial.

Boston Custer was portrayed by actor Patrick Johnston in the TV miniseries Son of the Morning Star (1991).