His brothers Virgil and Newton also enlisted. The 17th regiment was organized and armed at Alton, Illinois. On October 31, 1861, the unit fought Missouri State Guard forces near Fredericktown, Missouri. Over 60 troops were killed or wounded. 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 was discharged on March 22, 1863, as disabled.[1] Newton and Virgil served until the end of the war.[3]
For some time thereafter, he worked in a saloon in Wichita, Kansas, and then in 1876 as a deputy marshal in Dodge City, Kansas, under Marshal Charlie Bassett, who had replaced Ed Masterson after Masterson's murder.[3] From there he worked in Missouri, Arkansas, and Texas, working in saloons or as stage and wagon driver.[4]
In December 1879, he and his wife moved to Tombstone, Arizona Territory, along with his brothers Wyatt and Virgil. Their brothers Warren and Morgan and his wife Louisa joined them there in late 1880. The three younger brothers became involved in law enforcement in Tombstone, while James managed a saloon and worked in gambling houses.[5]
He was not present at the Gunfight at the O.K. Corral on October 26, 1881.[3] On December 28, 1881, his brother Virgil Earp was ambushed, shot two times with a shotgun. He survived, but only two months later on March 18, 1882, his brother Morgan Earp was assassinated in a billiard parlor.
The New Mexico and Arizona Railroad ended about 25 miles (40 km) away in Benson, Arizona. 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. Morgan's wife was already in Colton, where she had traveled for safety before her husband was killed. James Earp and two or three close friends accompanied the body to California.[4][6] Virgil and his wife Allie Earp followed the next day on a passenger train.
Morgan was buried in Colton, California. James then lived for a short time in Shoshone County, Idaho, until settling permanently by 1890 in California. James Earp died of natural causes in San Bernardino, California, on January 25, 1926. He is interred there at the Mountain View Cemetery.[4]