The Earp Vendetta Ride was a deadly search by a federal posse led by Deputy U.S. Marshal Wyatt Earp for a loose confederation of outlaw "Cowboys" they believed had ambushed his brothers Virgil and Morgan Earp, maiming the former and killing the latter. The two Earp brothers had been attacked in retaliation for the deaths of three Cowboys in the Gunfight at the O.K. Corral on October 26, 1881. From March 20 to April 15, 1882, the federal posse searched southeast Cochise County, Arizona Territory for the men they believed were responsible for the attacks on Virgil and Morgan. Several suspects had been identified and were charged, but were soon released by the court, owing in some cases to legal technicalities and in others to the strength of alibis provided by Cowboy confederates. Wyatt hoped that the legal system would bring the Cowboys to justice, but after suspects in both ambushes were freed, Wyatt resolved to take matters into his own hands.
On March 20, two days after Morgan's murder, Wyatt, his brothers Warren and James, Doc Holliday, and two other deputies were escorting Virgil and his wife Allie to a California-bound train in Tucson.