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Trebuchets in action at a siegeTrebuchets in action at a siege During the Middle Ages, the trebuchet was one of the largest and most powerful weapons in a siege army's armoury. It was a huge catapult, capable of flinging objects with great force and deadly accuracy from distances of up to 300 metres (1000 feet). As well as hurling rocks at the castle walls, it could also lob various other sorts of missiles into the castle itself, including firepots, dead animals or even human heads. Rocks could cause severe damage, but the others could harm or kill people inside the castle, start fires or even spread diseases.

A trebuchet is prepared for firing. A trebuchet is prepared for firing.

How it worked

The trebuchet was usually erected on-site and at some distance from the castle, before being brought up closer. A screen, made of wooden mantlets, was erected in front of it to protect the operators from arrows.

The trebuchet had a long arm with a sling at one end and a heavy counterweight at the other. Turning the winding gear lowered the sling end of the arm while operators loaded the sling with ammunition. The arm was locked in place at ground level by a trigger.

When the trebuchet was ready to fire, another operator released the trigger by striking it with a heavy mallet. The counterweight dropped rapidly, causing the arm to fly upwards. The missile, contained by a guide chute to stop it falling out of the sling, was hurled on its way.Fire! The trebuchet launches its missile.Fire! The trebuchet launches its missile.
Ammunition for use in a trebuchetAmmunition for use in a trebuchet


The largest trebuchets could fling rocks weighing up to 1500 kg (3300 lb), although the average weight of missiles was normally between 50 and 100 kg (110–220 lb).
