Two of his sons were involved in multiple conflicts in Cochise County, Arizona Territory including stagecoach robbery and cattle rustling.

Newman and Mariah had five sons and two daughters: John Wesley, Phineas "Fin" Fay, Joseph "Ike" Isaac, Mary Elsie, Ester Ann, Peter Alonzo, and William "Billy" Harrison.

He tried gold mining in California[1] before relocating the family to Dallas, Texas around 1853, where they ran a ranch for a time and where their last two children, Ester and Alonzo were born.

While in Texas, both Newman and his oldest son John enlisted in the Confederate Home Guard at the outbreak of the American Civil War.

Newman returned to the Arizona Territory in 1873 to the Gila River valley, where he purchased or squatted on a large tract of land outside Camp Thomas.

[1] After leaving Camp Thomas, Newman Clanton bought land on the San Pedro River, in Lewis Springs, where he built a large adobe house.

[3] In the same year prospector Ed Schieffelin discovered silver in the hills east of the San Pedro River on a plateau known as Goose Flats, less than 15 miles (24 km) from the Clanton ranch.

[7]: 193 The Clantons were reputed to be among a group of outlaw Cowboys who crossed the Mexico–United States border, where they stole cattle and re-sold them to the hungry miners in Cochise County.

[8] The Mexican government at the time placed high tariffs on goods transported across the border, making smuggling a profitable enterprise.

[9][10] The large numbers of men required to work the fast-growing mines led to a rapid increase in the demand for beef cattle.

Johnny Ringo who had participated in the Mason County War, siding with Texas Ranger and gunman Scott Cooley, became associated with the Clantons.

While hunting the murderers, Mexican Rurales led by Commandant Francisco Neri illegally crossed the border into Arizona and were ambushed.

Two years later, in July 1881, "Curly Bill" learned that several Mexican smugglers carrying silver were heading to the United States through Skeleton Canyon.

On August 12, 1881, Clanton and six other men began a journey herding stolen cattle sold to him by Curly Bill through Guadalupe Canyon near the Mexican border.

[13] Around dawn after the first day and night on the trail, they were ambushed by Mexicans dispatched by Commandant Felipe Neri,[14]: 110  in what was later dubbed the Guadalupe Canyon Massacre.

They moved it to the Boot Hill cemetery in Tombstone, where he was re-interred alongside his youngest son, Billy Clanton, who had been killed two months after his father's death, in the gunfight at the O.K.

In the summer of 1887, Ike Clanton was indicted for cattle rustling and was killed resisting arrest in a gunfight with law enforcement officers.

[22] In Call of Juarez: Gunslinger, Old Man Clanton is seen welding a Gatling gun and is killed by the bounty hunter Slias Greaves.