John of Barsoom was an officer in "King" Geoffrey's army during the Detinan Civil War. He commanded a brigade in the Army of Franklin. Like many of his colleagues, he chafed under the command of General Bell, who gave reckless orders and then blamed his subordinates for their failure. After being accused of cowardice by Bell before the Battle of Ramblerton, John of Barsoom sought to redeem himself by not shying away from danger, and as a result, he was killed.
John of Barsoom is based on Confederate general John C. Carter. John Carter is also the name of the narrator of Edgar Rice Burroughs' A Princess of Mars and of some of its sequels. In the books, Carter travels to the planet Mars and learns that people who live there call it Barsoom. Incidentally, the fictional John Carter was also a Confederate veteran.