steel knee capsPoleyns emerged in the second half of the 13th century and were the earliest type of plate armor added to a knights equipment. Worn over chainmail chausses, poleyns provided an extra layer of protection for the vulnerable knees. For armed cavalry, the legs were always a particularly exposed area. The development of poleyns coincided with the introduction of the shorter heater shield or knights shield, which replaced the older, taller kite shields