Darka will, I think.
Eston certainly had no intention of surrendering really until the last few weeks there. It just became pointless. The stalemate was broken, a duchy had seceded (and was collaborating with the enemy), and we could no longer field armies of significance. Darkan and BoM armies were no where to be found, and probably wouldn't have been able to help anyways, what with 2/3 of the island in a constant rotation sitting in Eston.
Sure, we could have slogged it out for a while longer. But all that would have done was ensure that Eston as realm truly was destroyed. The end result would have been similar, but probably without an actual Eston around any longer and with nobles ending up more scattered, etc.
The war had dragged on for so damn long, it was just time to throw in the towel one they were, ya know, TOing regions adjacent to our capital.
That pretty neatly sums up why Hammarsett surrendered.
