|The following is based on Fallout Tactics and some details might contradict canon.|
Osceolla was the main base of operations of Gammorin's (Paladin Latham's) super mutant army. It was a military compound constructed near the place where part of the Brotherhood of Steel Air Convoy crashed. Gammorin himself, as well as High Inquisitor Toccomatta was stationed here. Roshambo could be found in the ruins of the airship. The Brotherhood of Steel squad under the leadership of the Warrior came here to assassinate Gammorin and save General Simon Barnaky who was presumably kept here. They succeeded in their first objective, but the General was already captured by the Calculator's robot army. A letter to his wife, Maria, and a nuke control device, which could be useful with the nuke from Kansas City, were also retrieved.
The mission in Osceolla is to kill the Brotherhood traitor, Paladin Latham and to find General Barnaky.
Osceolla appears only in Fallout Tactics.