Why did the Recluce marines attack Lerris and Tamra at the end of The Death of Chaos? Lerris had literally just defeated the attacking Hamorans, so I can’t really follow the reasoning.

Earlier in the book there are sections mentioning Heldra and the black squads. They were opposed to Lerris coming to Recluce in the first place, and they believed, accurately, that even if Lerris prevailed, Recluce would be devasted (and they’d lose everything, which they pretty much did). So it’s not surprising that they attacked at the end.