it is a machine used in the 13th century to destroy castle walls. the used huge stones (250-300lbs) to break down the walls and hopefully hurt the enemy. they also heaved dead horses to spread diseases to the enemy. it is a machine used in the 13th century to destroy castle walls. the used huge stones (250-300lbs) to break down the walls and hopefully hurt the enemy. they also heaved dead horses to spread diseases to the enemy.