In ancient and medieval sieges, how were weapons such as catapults, ballistae, and trebuchets used? Were they used to break the walls, as in movies, or were they more used for wearing down the population in side by raining down destruction from above?

There were basically three types of missile hurling siege weapons pre-cannon; each is described by its method of propulsion. First there were the tension weapons, the ballista is the most well-known of these and worked by utilizing the stored energy from (usually) twisted ropes (it should be noted that the Romans did have a torsion version). The energy from one of these missiles could easily send a large bolt through multiple human targets. Second there were the torsion weapons; these are what most consider being the ubiquitous catapult. These work by forcing a plank over a fulcrum and then using that stored energy to hurl the missile through the air in an arc over the field of battle. Finally we have the counterpoise or counterweight engines; these are your trebuchet style missile hurlers. These were the ones which could toss the largest items the furthest distances.

Now that we have an idea of what kinds of pre-cannon projectile weapons were available we can look at their uses. Ballistae were best suited as castle defense, or anti-personnel because their bolts, no matter how large or well made, were not likely to do much damage to stone walls. Catapults could be utilized to send projectiles against fortified walls, though I would think their use against the walls of a full scale stone fortress would be limited. Trebuchets were the big boys, and they first made their appearance in the Mediterranean sometime during the 12th century. These things were most definitely utilized in the battering of walls and other defenses. These things were also used as defensive weapons as well. If a besieging army is camped outside of your walls, it’s great to have a weapon which can toss large balls of love at them while they are sleeping or to break up any advancement towards the walls.

Siege weapons such as these did not just toss boulders at walls though; they had other ammunition as well. It is well known that crusaders used trebuchets to hurl the heads of their defeated enemies over the walls of Nicea. There are other examples of entire bodies being tossed over as a way to spread disease within the walls of the keep. Fire was also another useful tool in the arsenal of both the aggressor and defender. Greek Fire is notorious as a sort of incendiary bomb which could be utilized not only to burn down a town or castle, but as a terror weapon as well.

I hope this at least gives you an idea what these things were used for and capable of. I’m afraid this isn’t my real area of expertise, but luckily I do have a few reference books on the subject I could answer you with. If anyone else wants to chime in with better or more up to date information I certainly won’t be offended.

References:

Medieval Siege Warfare

The Knight in History

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