How can you clear a wildland without killing the boss?

It's been my experience in FE that to clear a wildlands you have to kill the boss, clear all the goodie huts, and kill all of the wandering monster armies from that wildland, even if they have wandered out.  But with LH I was able to clear one of the wildlands by clearing all the goodie huts and beating the boss, even though one of the monster armies was still alive.  So I'm not entirely understanding the rules, but I thought that you at least always had to beat the boss.

Edit: Note that there was also a bug in FE where if you saved the game after you had started the wildlands quest, quit the game, then restarted the game and loaded the save, the wildland could never be cleared.  In other words once you started it you had to clear it without leaving the game.  I don't know if that bug still exists in LH.

Yeah, I've ended up fighting wildland monsters (not bosses) in every game I've played. Seemed to be normal behavior as addressed earlier in this thread.

The wildland I couldn't clear was the poisoned swamp. The quest said to 'heal the diseased land', but I couldn't see any way to do that, and had killed all the monsters and looted all the huts. The spell that I thought might do the trick couldn't be cast in their territory.

So, how are you supposed to claim those wildlands?

Chances are it was a runaway monster. I spent a lot of time waiting at the swamp edge, chasing off anyone who got too close, while I researched troops strong enough to survive. I had fenced off the south area, but it's possible that someone wandered north and out of reach. What confused me was that the quest text said that I had to heal the land, but I couldn't see any way to do it, and I had killed the main monster. Killing all the little monsters as well doesn't seem to connect.

I had one of my first FE games post release ended by a stack of wildland trolls which crossed a wildland border and crushed my only city at about turn 15. Not fun!

Stardock at least needs to make sure high level mobs (obsidian golems, troll warriors) don't wander. These creatures cause too many problems and I see nothing added to the game by having a pair of obsidian golems wandering at turn 1.

Ive nothing against creatures like shrills, darklings or ice wargs wandering out though, provided they aren't part of the clearing conditions.