Here some tips for seiges before the assault.

1) Take as many units as possible (and a general).

2) Take units built in castles, units from cities are very capable at deffending cities or castles they just seem to be lacking when seigeing so take a professinal army.

3) Dont take many missle units you'll do far better with more infantry.

4) Take a mixture of infantry dont take just loads of heavey infantry take roughly 4 stacks of spearmen aswell.

5) On your way to the place you want to seige (and while seiging) keep checking what mercs you can higher if youve got the money replace some of your units with better mercs. i.e. Merc spearmen are better then english spearmen so i try and replace them.

6) Scout around the city your seiging last thing you want is to be segieing a city then for a full enemy stack to attack you from the rear. So then youll be stuck in a battle with the enemy attacking you from the rear and front (bloody hard when that happens).

Against cities without your own artillary/seige weapons

1) Build 3 seige towers and 3 battering rams.

2) Move as close as possible to the city and have you heavey infantrymen man the seige towers and anything you want to the battering rams. Have the seige towers slightly infront of the battering rams and line up the seige towers directly infront of the wall section you want to attack so they can get to that section of the wall as fast as possible. And have your battering rams directly lined up with the gate and grouped together.

3) When the assault starts firstly send in all your seige towers first the enemy ballista towers & cannon towers should direct there aim at them. Straight after you order your seige towers in order one battering ram to attack the gate and the other two to move to just infront of the gate. So then if you lose one battering ram you've always got two more there right next to the gate ready to assault.

4) Charge everyone you have towards the walls and set them to loose formation right next to the walls. The reason you do this is to stop cannon & ballista towers raping your men as they cant fire at you at close range. And you set your men to loose formation to minimise the loses from enemy missle troops on the walls. If youve got any archers with you have them fire at the men behind the walls not the men on the wall as you'll kill more men IME.

5) Move your camera to the gate and rotate it sideways so you can see whats on the other side waiting (you dont get to look in the city untill you get men on the walls or through the gate thats why i do this.). If its massed cavalary Group all you spearmen together then indavidualy move them in front of the gate and when the gate is battered down charge them through first followed up by your heavey infantry you'll massacre them doing this.

If its infantry on the other side send in your heavey infantry first then spearmen.

Tip:- Have your general not far from your men when going through the gate and keep blowing that horn to rally them. Also dont have your men in loose formation put them back into tight formation when going through the gate.

6) Now youve got a big battle going on have your cavalry grouped together and charge them through the gate you dont really want them to attack though you want them to break through the big battle at the gate. If you can get them through ride around the city taking out any loose units not in the main battle at the gate except for spearmen stay clear of them. If there are no loose units and you break through smash them into the back of the enemys units at the main battle at the gate then pull them back and do it again they'll rout realy easilly doing this.

There you go you've just won the battle with minimum loses

Note:- if any of your seige equipement goes on fire pull your men away from it as they will burn too.

Against citadels/castles without your own artillary/seige weapons

You do pretty the much the exact same thing as i suggested with the cities
although this time you can do one of two things use your cavalry to chase the enemy (none routing) through gates dont engage them so you capture the gates and your men can get through to the next ring of deffenses no problem.

Or when you get through the first wall of deffences send your heavey infantry onto the walls in one of the corners of the compound and have them work there way round onto the second wall (all the citadel walls are linked in the corners) then move them along the wall to the gate to capture it and open it for the rest of your army.

Tip:- If you've got a one on one (units i mean) going on but only somthing like 20 or so of your men are fighting and the rest are scatered behind them. Double click behind the enemy unit and all the loose men will push up and get involved in the battle.

Also if you try getting the cavalry to follow the enemy through there gates use a disaplined cavalry unit one that wont charge at the enemy without orders. The idea is you want the enemy to get through the gate and you follow through if your men attack them the gate will stay closed.

Attacking cites/citadels with seige weapons/artillary

I never bother with seige weapons or artillary myself as i find it to easy but heres what i would do.

For seige weapons just have all your men hold back out of range of cannon/ballista towers group all your seige weapons together and move them forward and make as many holes as possible in the walls were the enemy has units on the walls. You might want to stick a unit of spearmen in loose formation in front of your seige weapons aswell so the cannon/ballista towers target them first. Once youve made as many holes as possible just charge in and massacare the enemy

For artillary hold everyone back out of range and blow up all the towers first then blow up a couple of holes in the walls. Once youve done that charge in and kick arse its just so easy thats why i never use artillary or seige weapons.