Milton Duffield was a seasoned gunman, claiming his first victim in 1854. That reputation must have helped him in some ways; in 1863, he was appointed the first US marshal for Arizona Territory, a post he held for two years.
He later turned to mining. In 1874, both Duffield and James Holmes claimed ownership of the Brunckow Cabin, near modern day Tombstone. Holmes was in the building when Duffield showed up, shouting and waving his arms. Holmes killed him with a shotgun blast. Holmes escaped before doing jail time. Duffield was buried at the site.