Any hints please on how to capture a leader so you can ransom him back for that large amount of florins you get for the ransom?

Just started a new Campaign on Expert playing the Byzantines for the first time. Trying to follow Katank's suggestion to trap and ransom the Egyptian Sultan in Antioch. Well, I have him trapped in the Antioch fort but I cannot capture him, he gets killed every time - eventually!

I have re-played this siege battle several times now. If I command it myself, I always kill the Sultan so there goes the ransom , he never gets captured. If I autocalc the siege battle, the Sultan always seems to be captured and I get all the florins I need to build up my provinces for many years to come - which then takes away much of the challenge !

Is this a bug or is there a trick to capturing a leader like this without auto-calcing? I hasten to add the Sultan dies in melee fighting, not by an arrow.

I do not want to autocalc a battle just to get a particularly favourable result when I intend to play the whole campaign fighting battles myself. Seems like cheating to me. Not saying autocalc generally is cheating as the strategy part of the game, rather than the battles, is what some people play MTW for, especially for a fast campaign. Just don't want to have to autocalc a battle just to get a particular result, ie the ransom!

Tomcat