In medieval Europe, when besieging a castle there was a variety of siege engines, from battering rams to ballistas. The engines usually are classified into two types: projectiles and other. The most common types of projectiles are the mongrel (a type of catapult that gets its power from twisted ropes), the trebuchet (which gets its power from a heavy counter weight) and the ballista (which is a giant form of crossbow that could also fire stones). The most common other types of siege engines are the battering ram used to smash corners and burst through gates, the belfry, a siege tower used to get people onto the walls with archers on the top to give cover fire, and the cat, a type of cover that people used to protect themselves when filling in the moat or mining at the walls [sapping]. The cat is also is called a rat or tortoise. Which one, do you think, was the most effective when attacking a castle?