Peasants are armed with pitchforks and are the weakest of seven but they are also very cheap. Macemen have light armor and are good for chasing down archers. Pikemen are slow defensemen, good for defending archers and crossbowmen. Archers are short on defensive capabilities but have a great range for mowing down light-armored troops at a distance. Crossbow men fire at a slower rate but their shots can penetrate armor.
Swordsmen are slow but strong and can hold up against archers.
Horsebacked Knights are very fast, only the crossbow can really slow them down. Before any battle you have the choice to control it or let the computer decide. This is a nice feature because if the battle if hopelessly one sided and you might not want to bother fighting it out. Sometimes in a long game you might get tired of the battles and just want to get it over with. You may want to fight even the hopeless battles if you have ranged soldiers who can be carefully positioned behind rocks or other soldiers.