Blackfoot

The Blackfoot were a tribe from Arizona. It was the first of the tribes that Caesar took control of and forged into his Legion.

Background
At some point in 2247, Mormon missionary Joshua Graham, as well as two Followers of the Apocalypse - Bill Calhoun and Edward Sallow, the young man later known as Caesar, were captured by the Blackfoot tribe for ransom. At the time the tribe was at war with seven other tribes, a war they were inevitably going to lose. Unwilling to be destroyed along with them, and against the wishes of his companions, Caesar chose to use his knowledge to train the Blackfoot tribe in the art of warfare after witnessing their lack of knowledge first hand. He showed them how to clean and maintain guns, operate with small unit tactics, create their own explosives and to strike at their weakest enemies first; divide et impera - divide and conquer (Latin). He quickly impressed them enough to the point where he was made their leader.

He soon introduced the concept of total war to the tribes around them - Caesar knew that though the tribes had always fought each other via occasional skirmishes, he considered them to only be "playing at war" having never seen warfare at its most destructive and barbaric. They defeated the weakest of their enemies first and enslaved many of the able-bodied survivors but Caesar had the rest, including women and children, killed and their remains piled high. When they confronted the next tribe, they brought an emissary back to view the carnage. The concept of total war was an entirely new, and terrifying, facet to his strategy that they had never confronted before and would form the core of the Legion's tactics and outlook.

Joshua Graham decided to join Caesar as his right-hand man, now known as the Malpais Legate. While Calhoun was sent back to the Followers to inform them of what he was doing. Caesar formed his Legion out of the tribes that had either been conquered or had chosen to capitulate to avoid total destruction. Caesar chose the concept of the Roman Empire to model the Legion after because of its parallels to what he considered the status-quo of the post-apocalyptic world. Ideologically, the Roman Empire was also appealing to him for its ability to assimilate those it conquered, the destruction of such "tribal" identities a key goal to the Legion's long-term strategy of unification. He intended to erase their individual identities and replace them all with a single, monolithic culture - the Legion - where individuals have no value outside of what they offer the greater whole; long term stability at all costs.

If the Courier speaks with Canyon Runner, he mentions being a former member of the tribe, and that they were the first conquered by the Legion.

Appearances
The Blackfoot are mentioned in Fallout: New Vegas and its add-on Honest Hearts.