In-game, Beaumont wields two long knives in combat.
Beaumont is mentioned to have been a member of the New Orleans aristocracy at one point, but he left the city for the less luxurious life of a trapper, prospector, and hunter. A senior member of the Circle of Ossus, Beaumont uses his knowledge of the wilderness to the Circle's advantage.
During the Mexican-American War, Beaumont and a party of armed men were forced to flee northward, to the shelter of an American fort. When the fort was besieged by the Mexicans, he assisted its commander, Major Cooper, and entrepreneur Amelia Black in defending it. Discovering Amelia's status as a member of the Black family, the Circle's enemies, Beaumont devises a trap for her in an old mine. Failing, he flees, but arranges Major Cooper's murder at a later time. However, his various attempts to kill Amelia or to thwart her plans fail.
Traveling to the Circle's Havana stronghold, he orchestrates the Circle's defenses against Amelia's incursions into their territory. Finally, she arrives in Havana, with American and Spanish government support, and attacks the Circle's stronghold. Beaumont survives the stronghold's fall and ambushes Amelia and her Iroquois great-uncle, Kanyenke, as they enter through a gate. Kanyenke prevents him from killing Amelia, who shoots Beaumont.