The torsion catapult is a siege weapon from the Middle Ages. It will be one of the weapons of William the Conqueror
Description
The torsion catapult consisted of a large frame placed on the ground (or sometimes with wheels) with an axle running between the sides of the frame. A vertical arm is attached to the axle, with torsion springs around its base. The arm typically had a bowl-shaped bucket on the end.
Use
To fire the torsion catapult, the arm is drawn back with a windlass, with a pin preventing it from being flung forward by the torsion springs. A large rock or another heavy object was placed in the bucket and the pin is struck, the torsion springs throwing the arm forward and propelling the object. This siege engine was originally developed by the Romans and remained in use until the advent of the cannon.