Endemic warfare during the Middle Ages forced knights to live in fortified castles. The castle served as a base of operations from which the knight could defend his land and people. The castle builders gave every detail a defensive purpose.
Castles developed slowly during the Middle Ages. The Normans developed the first castles in the 10th and 11th centuries. The simple design consisted of wooden blockhouses surrounded by a palisade on top of a huge mound of earth. In the 12th century castles developed into elaborate stone fortresses with many clever defensive features.
Built against the wall, the castle's spiral staircase curved in a clockwise direction going up and counter-clockwise going down. A person going up stairs supported himself with his right hand while the person going down supported himself with his left.
Most knights and soldiers in the Middle Ages carried their weapons in their right hands. The design of the staircases gave the defenders the advantage by keeping their right hands free to wield their weapons as they came down the stairs while attackers were forced to simultaneously handle a weapon and support themselves with their right hand.