Drawbridge — Middle Ages

The story behind the answer

Castles often spanned their moats with a hinged wooden bridge that could be hauled up by chains and winches to seal the entrance. Raising it removed the only approach across the ditch and turned the gateway into a sheer wall, stranding attackers under arrows and “murder holes.”

Used alongside a portcullis (a vertical gridded gate) and protected by the gatehouse, it formed part of a layered defense system. The mechanism relied on counterweights and pivot pins, allowing a few guards to operate it quickly during alarms. The idea outlived the Middle Ages, appearing at fortified manors and later on canal bridges; the “draw” simply means to pull it up.