[It's Hal who answers.]

Over a decade ago there was a schism. Elder Lyons thought that the Brotherhood should work with the local people of the Capitol, help them. The Outcasts thought that this was a violation of the codex and refused to obey. Then it got messy. Outcasts and non-Outcasts were killing each other over it.

My dad was killed in one of the skirmishes.

So Elder Maxson ending that civil war...it was a big deal.