Caleb Hammer first appeared in 1980's Marvel Premiere #54. He remained in obscurity until 2000 when he was one of the characters featured in Blaze of Glory. In the mini-series he chases after Kid Colt, later teaming with him and other Western heroes to defend the town of Wonderment, Montana. During the battle the bounty hunter Gunhawk shoots Kid Colt in the back despite also agreeing to put aside his chase of the Kid to defend Wonderment. Hammer strongly disagrees with this action and ends up killing Gunhawk.
X-Force #37 featured the death of Caleb Hammer. In a flashback in that issue one of the Externals named Absalom remembered shooting an elderly Hammer in the back after Caleb refused to participate in a duel with the young outlaw.