|The following is based on Fallout Tactics and some details might contradict canon.|
Gammorin's Army is one of the two most important offshoots of the Master's Army, along with the Attis Army, initially led by a super mutant called Gammorin, and later by ex-Brotherhood of Steel Paladin Latham, who took Gammorin's name as his own.
Some time after their departure, Gammorin's mutants were pursued by Brotherhood of Steel airships. While most of them ended up in the vicinity of Chicago, far from Gammorin's forces, one of the zeppelins crashed north of the mutant encampment. The leader, Paladin Latham, challenged Gammorin to a single unarmed combat and, to surprise of everyone, killed the mighty mutant. As he defeated the previous chieftain, the super mutants expected him to become the new leader of their army. Latham suffered a head injury during the combat, and throughout the years, he grew more and more insane, even though he managed to organize the mutant forces into an army nearly as powerful as they had been during the Master's reign. He begins to see the super mutants as his own people, however, he hasn't forgotten the Brotherhood and his past.
When Latham's forces encountered Calculator's robots from Vault 0, he swore an oath to destroy the cybernetic menace. By that time, he assumed the name "Gammorin", after the mutant chief he had killed. Gammorin's mutant scientist ran extensive research in order to find a cure to super mutant sterility. However, his laboratory in Jefferson City was taken or destroyed by a splinter faction of the Brotherhood of Steel from the Chicago area, who believed it to be a weapons manufacturing plant. Eventually, Latham and his forces were defeated by the Brotherhood. When he was encountered by the Warrior and his squad, he comments on the elder's foolishness and blindness to a new menace from the west, which only his mutants are able to fight. Being engaged in combat and wounded, he shouted that all he has done was stop the menace, and then died. After the defeat, many mutants were, however, allowed to join this Brotherhood to fight against the robots. The Brotherhood tried to continue the work on the cure to super mutant sterility, but they were unsuccessful.
Gammorin's Army appeared only in Fallout Tactics