After making it through the two gates for a siege (outer and inner gate) the defenders form a shield wall behind the inner gate.
Lift up your shield and politely side-step to the right or left of the shield wall. Say "excuse me good sir" for good measure.
Run to the back of the shield wall they've made.
Repeatedly stab then all in the back, quite literally. Repeat this process until they are all gone or retreating.
So long as there are still some of your troops at the gate, the entire shield wall AI will ignore your existence as you massacre them all. Occasionally, the one you stab will turn around, but then go back to their shield wall as if nothing happened.
Lift up your shield and politely side-step to the right or left of the shield wall. Say "excuse me good sir" for good measure.
Run to the back of the shield wall they've made.
Repeatedly stab then all in the back, quite literally. Repeat this process until they are all gone or retreating.
So long as there are still some of your troops at the gate, the entire shield wall AI will ignore your existence as you massacre them all. Occasionally, the one you stab will turn around, but then go back to their shield wall as if nothing happened.