I don´t agree with you sir_schwick. Strenght of knights lay in their horses. Those horses were heavy, medium fast and not very manouvarable. Knights were armed with lances, which were quite long. Now imagine a clash of a third of a metric ton against a man. No matter how armed you are or how big is your shield, you won´t be able to stay on your feet after the clash. But if unmounted, knights were too heavy with their armor manouver in infantry-like fashion. They were probably very good in man-on-man combat but as I said they were very slow and not trained to be infantry. In 1302 Philip IV the Fair was defeated in Flanders at the Battle of the Golden Spurs. He had 2500 knights, Flames had non. In 1320 Philip V the Tall fought and lost a battle agains Flames in which he dismounted his knights hoping he won´t repeat Philip the Fair´s defeat. I just want to point out that mounted units are good only in certain circumstances, and these don´t include siege.