There has been some debate about this, but I think it is reasonable to assume that without an alliance, combat does not end until only one side's units occupy a hex, even if warlords are present. Therefore, when attacking, in order to take a hex (or zone thereof), you must either a) slaughter or b) turn/capture all enemy units. The enemy units retreating is not an option, since they have no move on your turn.
We also know from klog #12 that "Turned and captured units have notoriously low loyalty to their new side, unless you put a spell on them. Capturing is usually reserved for valuable Casters"
As has been discussed before, this means that when one side conquers another, it does so by killing ~99.9% of the conquered troops
. Yeah Ansom, real noble.
We also know two more relevant items:
1. Parson is having serious issues with leading slaughters.
2. Units can be loyal even without a high Loyalty stat, based on their own psychology and humanlike motivation (Wanda's dedication to Stanley in pursuit of her prophecy, Vinnie's dedication to Ansom, Jillian's obsession with Wanda and love for Ansom).
Now...again going to Romance of the Three Kingdoms, there's an interesting mechanic that was present, at least in the older games. When you captured an enemy general, you had three options: Recruit, Execute, or Free. Most of the time if you did Recruit, the general had very low loyalty until you bribed the boop out of them (aside from story-related stuff that made certain generals like certain rulers), which took multiple turns and a lot of cash. But on the other hand, if you selected Free, the general would be a free agent just floating around the map, moving from province to province each turn. If you, on your first turn, sent a high-charm emissary to visit them, they'd normally join you at normal to high loyalty
(again, outside of story reasons making certain generals hate certain rulers). A great, low risk, bribery-free way to get good generals that simulates gracious capture, mercy, and fair "employment" offers.
So, there's a prediction in here, right?
Parson will have a side completely defeated, including killing the overlord. But instead of then slaughtering the remaining enemy units he withdraws, turning the city neutral. Next, he sends diplomacy units in to offer "turn or be neutral", rather than "turn or die"
. No one has ever considered mercy of this degree before, since everyone always wants to capture cities rather than just neutralize threatening sides. Shocked (and previously wondering who was going to pay their upkeep), the units all agree to turn, and are extremely loyal to Parson (and not necessarily his overlord) despite having low Loyalty stats because he offered both mercy and a "job".
(This would work even better by simply withdrawing and granting true freedom, then making the offer to turn a turn or two later, except the "time freezes until attacked" mechanic for neutral cities also explained in klog #12 screws that up. True freedom isn't an option when it means time freezes for you. What would allow this to happen is if Parson could hold all but one zone, and not be forced to take the whole hex before ending turn, but we don't know if that's possible. Ansom rushed the last GK zone in the same turn.