Brotherhood of Steel (Chicago detachment)

The Chicago detachment of the Brotherhood of Steel, also known as the Eastern Brotherhood of Steel, is a rogue chapter of the larger Brotherhood, who by 2254 had fallen off of the radar of the organization's other chapters.

Background
The Chicago detachment's origins lie in the airship dispatched by the New California Brotherhood, to track down the remaining super mutants of the Unity. While the majority of these airships were destroyed or scuttled, one crash landed near the ruins of Chicago. The survivors initially organized themselves into a new chapter, but by 2254 they had gone rogue, cutting all contact with the larger Brotherhood. The expedition that would become the Brotherhood's Eastern Division attempted to restore contact during their journey to the Capital Wasteland, but failed, and by 2287 records of their status were in dispute.

Appearances
The Chicago detachment of the Brotherhood of Steel is mentioned only in Fallout 3 and Fallout 4.

Behind the scenes
This faction is all that remains from Fallout Tactics. Fallout 3 explicitly retconned nearly the entire game, while Todd Howard explained in a related interview that as far as Bethesda is concerned, neither Fallout Tactics nor Fallout: Brotherhood of Steel happened.