Slightly off-topic but in one assault on a wooden fort, I mis-clicked, thinking I'd ordered a bunch of peasant to move to a position inside (ie click on the ground, or drag out a formation), expecting them to march in through the broken gate and then form up. To my surprise, they marched up to the wall (straight-line route-plotting algorithm at work) and they began their 'attacking' animation. I got busy with other goings on but, after a minute or so, I heard a crashing noise and turned to see the wall falling down and my peasants merrily marching in through a BIG hole in the wall.

Just goes to show you don't actually need siege gear to break into the wooden forts...

My siege battles have a nasty tendency to cause the PC to reboot itself so I autocalc most of them now, which is a pity since I've recently put the VI expansion in place and the sieges are supposedly far more deadly on your assaulting troops now. Autocalc seems to let them get off lightly, if you use enough of them.