The battering ram was used during a siege to break down the castle gate—but could be brought in to smash the walls as well. The ram was housed inside a timber carriage, called a penthouse (and nicknamed the “cat”), to protect the footsoldiers from the onslaught of arrows and crossbow bolts. Wet hides were fixed to the outside of the roof to prevent it from being set alight. Under the roof, a thick tree trunk was suspended on chains or ropes from the frame. The front end was tapered to a blunt point and reinforced with iron. The soldiers then swung the ram backwards and forwards against the target with as much force as they could muster. Once the gatehouse entrance was destroyed, the attackers could swarm inside the castle.

Filling in the moat

Before a battering ram could be wheeled up to the castle gatehouse, the moat had to be filled in. The drawbridge would have been pulled up, so the attackers needed a new bridge for their weapon. In order to get men close enough to complete this essential task, another wooden penthouse or "cat" was needed to give them protection.

Under cover of the penthouse's sturdy roof, the men dropped earth, rubble and fascines (bundles of sticks), out of the front of it into the moat, creating a temporary bridge for the battering ram to make its approach.