Just thought of another thing. Sometimes my army gets really messed up after a fight. Instead of using my knight's healing ability and just sitting there, I'd rather be able to transfer my whole army into the city and the defending army out so that I may heal them all more quickly with the wells. Even if I had one open slot, I would have to slowly transfer units over one by one to send them all into the city.
Maybe look at the Total War series and see how they do it. It's similar with the armies and such.