Siege weaponry and technology deteriorated during the Dark Ages. However, the invention of the trebuchet in the 12th century reversed that trend. The trebuchet represented a leap forward in siege engineering. Instead of throwing missiles purely through torque, as the catapult did, the trebuchet used a sort of see-saw motion, with a heavy counterweight opposite the launching end to accurately throw rocks and other missiles great distances. Some trebuchets were even adjustable, so their force, arc, and range could be changed by the crew without moving the contraption itself.