Tom Horn was a civilian scout in the Apache Wars (between 1849 and 1886), in Arizona. He saw heavy action in numerous fights with Apache warriors. He eventually rose to the position of Chief of Scouts. Tom Horn was also present at Geronimo's final surrender at Skeleton Canyon, Arizona, on September 4, 1886, acting as an interpreter. Geronimo was said to have been so impressed by his knowledge of the Apache language that he gave Tom Horn an Apache medicine bag with rocks, small bones and other sacred objects. Tom Horn had the contents up until his hanging and he never let people touch them. Geronimo, still a prisoner of war in 1903, later heard about Tom Horn's unfair hanging and commented that Tom Horn had been a great warrior, and he also believed him innocent.
After the Apache Wars, Tom Horn used his Chief of Scouts earnings to build his own ranch in the Galiuro Mountains near Aravaipa Canyon in Arizona. Cattle thieves robbed and burned his ranch one night. This led to his extreme hatred of cattle thieves in Wyoming.
Contrary to the statement at the beginning of the film, Geronimo never was captured. Geronimo surrendered and met with United States Military officers, surrendering to General Miles on September 4, 1886 at Skeleton Canyon, Arizona. A pile of stones still marks the site of Geronimo's surrender. Tom Horn personally escorted Geronimo to the train station at Bowie Arizona that transported the Apache captives into exile in Florida. Tom Horn had much admiration for the old Apache war leader and never tarnished or defamed Geronimo's exploits.
William Goldman wrote a full-length feature film script, intended to be a cinema release starring Steve McQueen and directed by Don Siegel. McQueen fell out with both men and made his film with others - "Tom Horn" was finally released, after many delays and changes of personnel, in 1980. Goldman's script was converted into this two-part TV movie, with many alterations of which Goldman disapproved.
Tom Horn arrived in Arizona Territory in 1881. There is some debate whether he was a hired gun or killer for hire in The Pleasant Valley War (a range war fought in Pleasant Valley, Arizona in the years 1882-1892). The Pleasant Valley War had the highest number of fatalities of such range conflicts in United States history, with an estimated total of 38 to 64 deaths, and the near destruction of the males of the two quarreling families. The war was fought between two feuding families, the ranchers Tewksburys and Grahams. Army quartermaster records show that Tom Horn was first employed in September 1881 as a teamster at Whipple Barracks, near Prescott Arizona. Some say that Tom Horn had killed at least three men, but nothing is confirmed. Both sides of the feud suffered abounding murders to which no suspect was ever identified. In his autobiography, Tom Horn writes: "Early in April of 1887, some of the boys came down from the Pleasant Valley, where there was a big rustler war going on and the rustlers were getting the best of the game."