Unpaid military service, usually of forty days' duration, owed to lord or king in return for tenure of land. (Frame, Robin. Colonial Ireland, 1169-1369, 144) Related terms: Knight's Fee / Knight

tenure by the duty of providing a knight or knights to fight for an overlord in time of war or man his castles in time of peace.

Initially the knights rewarded with grants of land had to perform knight service to the king and his barons but over a few generations this military service was separated from the holding of land and the military service was commuted to a money payment known as “shield money” (scutage) and with these fees the king was able to pay fighting men.