It happens sometimes that the enemy thinks you are dead and you are not taken prisoner. Most of the time you get captured though... Lords with high honour and a high relation rating towards you may also let you go when you lose a battle.
GenericSoldierX 说:
I had a 170 man army, and was attacking some 60 man Nord army, I randomly got knocked out, lost my entire army and got taken prisoner, the auto-resolve system is a ****ing joke.
That´s why you need companions at the bottom of your list with First Aid skills.
Or better, wait a few weeks till we get mods that let the battle continue after a knockout...