The trebuchet was a siege weapon similar to a catapult. It used a weight or was pulled to launch a projectile.
A trebuchet was usually wooden and rather large, which was necessary to create the best balance of ease of use and force. There were two types of trebuchet: the traction trebuchet, operated by the pulling of several soldiers on a rope, and the counterpoise trebuchet, which operated by a heavy weight.
Both kinds of trebuchet were composed of a rectangular wooden base, a pivot, an arm (usually a strong, square beam), and a sling at one end of the arm. On the other end of the arm was the counterbalance (usually a large quantity of wood bound together) or the rope, depending on the type of trebuchet.
The counterpoise design was operated similarly to the catapult: the sling end of the arm was pulled back and down, the projectile was loaded, and it was released. The traction trebuchet did not launch until pulled by the men.