In 1861, at 19, he enlisted in the Union Army at the outbreak of the American Civil War, joining Company F, 17th Illinois Infantry on May 25, 1861.

James was severely wounded in the shoulder and temporarily lost use of his left arm, but he remained in the army for over a year.

He lived in Colton, California, Helena, Montana, Pineswell, Missouri, and Newton, Kansas, before he wed the former prostitute, Nellie "Bessie" Ketchum, in April 1873.

The three younger brothers became involved in law enforcement in Tombstone, while James managed a saloon and worked in gambling houses.

On Sunday, March 19, Wyatt and James Earp accompanied Morgan's body in a wagon to Benson, where it was loaded onto a freight train for immediate shipping to Colton.

James then lived for a short time in Shoshone County, Idaho, until settling permanently by 1890 in California.