Though only a teenager at the time, Billy the Kid wounds an Arizona blacksmith who dies the next day. He was the famous outlaw’s first victim.

Just how many men Billy killed is uncertain. Billy himself reportedly once claimed he had killed 21 men—“One for every year of my life.” A reliable contemporary authority estimated the actual total was more like nine: four on his own and five with the aid of others. Other western outlaws of the day were far more deadly. John Wesley Hardin, for example, killed well over 20 men and perhaps as many as 40.

Having fled from his home in New Mexico after being jailed for a theft he may not have committed, Billy became an itinerant ranch hand and sheepherder in Arizona. In 1877, he was hired on as a teamster at the Camp Grant Army Post, where he attracted the enmity of a burly civilian blacksmith named Frank “Windy” Cahill. Perhaps because Billy was well liked by others in the camp, Cahill enjoyed demeaning the scrawny youngster.

On this day in 1877, Cahill apparently went too far when he called Billy a “pimp.” Billy responded by calling Cahill a “son of a bitch,” and the big blacksmith jumped him and easily threw him to the ground. Pinned to the floor by the stronger man, Billy apparently panicked. He pulled his pistol and shot Cahill, who died the next day. According to one witness, “[Billy] had no choice; he had to use his equalizer.” However, the rough laws of the West might have found Billy guilty of unjustified murder because Cahill had not pulled his own gun.

Fearing imprisonment, Billy returned to New Mexico where he soon became involved in the bloody Lincoln County War. In the next four years, he became a practiced and cold-blooded killer, increasingly infatuated with his own public image as an unstoppable outlaw. Sheriff Pat Garrett finally ended Billy’s bloody career by killing him on July 14, 1881.