Doing the Istania, Empire declares war on me, quest. Destroyed the Northern Empire prior to this beginning... At the start after they declared war I would have 30 or more lords prisoner in one town. I would go to the closest settlement to get more troops, return immediately (less than 1 day) and 5 of the lords would be gone, with no messages about escapes or ransoms paid. Because of this, I would also find that every day an army of 400-500 would attack the town, many times with the lords I captured a couple days ago.
Finally, I decided to start executing them because it was a losing battle with me losing 10 troops I didn't have time to replace before they returned with 500 they could easily replace. Now their armies still attack regularly, but maybe 1/2 as often and with an average of maybe 200-250 troops. I've probably executed over 100 lords and destroyed a number of (mostly small) clans now. Honestly, it shouldn't be this hard to make progress on easiest setting.
I like to play my games as a good guy. In this game I think of myself as someone trying to unite all the kingdoms, end the wars, and make things safer for the general populace. I can't picture myself that way and it makes it less fun when the only way to win is to execute everyone you meet.