The work crew heaves on ropes to lift the trebuchet's 13,000-pound arm, cocking it like an enormous wooden trigger. Twelve men yank on the firing pin to release it, but it doesn't budge. When they finally yank it free, the giant trebuchet swings, launching the stone ball like a mechanical pitcher lobbing a giant stone softball.
With terrifying majesty, the ball arcs and then lands 40 yards short of the castle wall. The trebuchet works.