James Calhoun was a soldier in the United States Army during the American Civil War and the Black Hills War. He was the brother-in-law of George Armstrong Custer and was killed along with Custer in the Battle of the Little Bighorn. His brother-in-law Myles Moylan survived the battle as part of the forces with Major Marcus Reno and Captain Frederick Benteen.

The Battle of the Little Bighorn, known to the Lakota and other Plains Indians as the Battle of the Greasy Grass, and commonly referred to as Custer's Last Stand, was an armed engagement between combined forces of the Lakota Sioux, Northern Cheyenne, and Arapaho tribes and the 7th Cavalry Regiment of the United States Army. The battle, which resulted in the defeat of U.S. forces, was the most significant action of the Great Sioux War of 1876. It took place on June 25–26, 1876, along the Little Bighorn River in the Crow Indian Reservation in southeastern Montana Territory.