|The following is based on Van Buren and has not been confirmed by canon sources.|
In the year 2231, he was leading a thriving Brotherhood of Steel, and decided that it was time to expand the Brotherhood's operations into the east. He sent an expeditionary force composed of five paladins to confirm the location of Peterson's bunker. The expedition leader, Andrea Brixley, discovered the bunker, disabled its security, and opened it for habitation. For over a decade, she and her fellow paladins explored the east and forged relationships with many of the tribes that inhabited the area.
In the year 2242, Jeremy Maxson renamed the bunker after his famous ancestor, Roger Maxson. He then sent a full compliment of troops for occupation. Andrea Brixley was promoted to Elder, given the rank of General, and placed in charge. The remainder of her exploratory team was given the title of Elder as well. It was not long afterward that the war with the New California Republic was announced.
Jeremy Maxson does not appear in any game. He was only ever mentioned in Van Buren design documents, but wasn't going to appear in the game itself. According to Van Buren, he was the leader of the Brotherhood of Steel at the time of Fallout 2.