Doniphon was a planet in the Outer Rim's Kwymar sector, in the system of the same name. Doniphon was invaded by the Galactic Empire in 17 BBY, during the Empire's suppressions of rebel activity in the sector. An Imperial platoon succeeded in rooting out Doniphon's dissidents, although promising stormtrooper commander Beilert Valance suffered grave wounds in the process.
During the Imperial Period, Doniphon became a hotspot of combat, as one of the worlds caught up in the Imperial campaign known as the Kwymar Suppressions. Along with several of its Kwymar sector neighbors, Doniphon became the site of violent battle between local rebels and Imperial forces led by an ambitious young stormtrooper commander named Beilert Valance. During the assault on Doniphon, Valance and his crew cleared a rebel outpost near the Pyrand River in brutal close-quarters fighting, advancing from there to move on fighters dug into the Selpathian Hills the next day.
Although the Imperials were jamming their transmissions, the rebels managed to get a transmission through to compatriots in the town of Damatua, who sent starfighters that strafed Valance's platoon. Although the Selpathian rebels were soon terminated, the squad sustained 21 casualties, Valance among them. Although the commander survived, the Imperial assault on Doniphon proved to be Valance's last mission with the Empire, as his extensive injuries forced him to be relocated to Anglebay Station on Telos IV, where he was rebuilt with cyborg parts.
Although Doniphon appears in a flashback in the Marvel comic, the site of Valance's injuries went unidentified until 2004, when author Jason Fry gave it the name "Doniphon" in the Star Wars Miniatures scenario Mission 2: Destroying the Past. According to his endnotes, the name is a reference to the 1962 western The Man Who Shot Liberty Valance. Fry believed that Goodwin named Beilert Valance as a reference to the film, and in turn named Doniphon after a character in that film, Tom Doniphon.