The Master lamented the needless destruction of the Great War. In order to avoid the self-destruction of his species, he desired to forcefully evolve humans into one race he proclaimed to be a "perfect race", removing the inequalities that are the cause of strife among humans. According to the Master's plan, if everyone could be as perfect as his super mutants, there would be no more conflict. Those who could not evolve would die. Around 2155, the Master began seeking out uncontaminated humans with which to create mutants in used the Forced Evolutionary Virus (FEV), and build his super mutant army, named the Master's Army. It was the first step of the Unity, his perfect vision of humanity.
In his attempt to become master of all humanity, the Master tried to create guardians through gene splicing, but was stopped by the Vault Dweller before he could complete his plans. However, some of his creations have outlived him and continue to roam the wasteland. These abominations include centaurs and floaters, which are often found together as though they feel some sort of kinship for another.
The Master's Army was composed of:
- 1st and 2nd generation mariposa super mutants, some brilliant and many dumb brutes.
- Nightkin, elite forces of super mutants that used Stealth Boys.
- Centaurs, creatures created with mix of humans, dogs, and other types of animals into a FEV vat.
- Floaters, mutated flatworms with FEV and Master experiment.
- Vat Team 9 sergeant
- Dog and God
- Dying mutant
- James T. Roche
- Jim Grimm
- Joe Grimm
- Lily Bowen
- Mean Sonofabitch
Master's Army appeared only in Fallout but is mentioned in all Fallout games.