I've had generals sallying during a siege battle trying to take on the rams/cannon etc that can take down the walls, problem is the gates are open and if they try to disengage I send in my troops behind them .... makes for an easy entrance.

I have had about 2 or 3 of these missions in my English campaign, against the spainish (was at war with them too), byzantians and some one else. The Kings may have become paraniod due to my suicide 1 - 3 skill level assassins trying to take him out every turn for 10 turns hehe.