How do you defend in sieges?

[Dayve]

I was waiting in a Southern Empire city (I am a vassal of them) with my army of 50 men. The city got sieged. I can see the siege of the city happening on the map. My only options are to sally out or break out. Where is the option to man the walls and defend the city?

[Archaist]

you wait. The enemy hasn't attacked yet, they need to build their siege camp first. Once the camp is built they can attack with ladders, but thats suicide so they'll probably wait untill they have a siege tower or battering ram and then attack.