Thanks for the replies guys - I was actually on the defensive when the besiged force sallied forth.

Akka - you are correct. I started a new campaign and in a few siege battles I threw all my men into the breach. Was interesting as I could actually watch the ebb and flow as the enemies initial charge was slowed, stopped and then reversed as I brought more men into the fray.

I think your point about the extra movement is also valid as the cav on both sides seem to be moving quite oddly in these big all in brawls. Still not sure what to make of them as they are hardly tactically interesting but actually quite fun to watch now I know to throw everybody into the mix. Although I did have time to pull some men from one flank to the other to shore up a hole that was forming which was a pleasing result.

Coming from MTW I held my troops in reserve and used them to plug gaps when the line got thinned. That’s what was getting me killed in M2TW.

I still think bridge battles are a bit silly but again I think I am better off to let the enemy spill out off the bridge and trap them as per suggestions above – this should negate their “push” effect I hope.

Thanks for the advice - I've started a new campaign but I may go back to an earlier save in the previous campaign to try a what if scenario.

Cheers