Catapults were used to knock down castle walls. Most catapults were made of wood. The size of the catapult varied depending on how far the attackers wanted the boulder to go. The bigger the catapult the more powerful it would be. A catapult had a long pole laying on a stand, and some stands had wheels and were movable. On one end of the pole would be a large bowl or net to hold a boulder or stones. The other end of the catapult had a counterweight. The end of the bowl would be tied down and when the ropes were cut, the counter weight would swing down and the rock or boulder on the other end would fly into the air. The boulder would hit the castle wall. Now ground attackers could storm in the castle or more boulders would be shot to knock down the castle. The catapult was a very important weapon in the late 1200's because walls were built stronger and thicker.