What was the purpose of a ballista in Medieval warfare?

August 10, 2017 7:40 AM

I watched this previous week's game of thrones and my wife and I had a discussion of what the actual use of a ballista was in warfare of the Middle Ages. I have to admit I don't really get the use case. A Catipult could send huge stones to destroy walls and infrastructure and, of course, kill people in its path. Grape shot is like being able to fire numerous sling bullets. But I can't quite picture the use case of a ballista. Was it to fire at infantry? If so why was it better than other tools?
posted by ArthurBarnhouse to Society & Culture (4 answers total)

Best answer: It was primarily an anti-personnel device used by both sides in siege warfare, fired against fixed targets or defending them against massed attack. In its heyday (Punic Wars through Roman Empire) the ballista provided more accuracy at longer ranges (up to about 500 yards) than other weapons (though with a lighter projectile).

By the Middle Ages, it was supplanted by more powerful anti-fortification weapons like the trebuchet, as well as more powerful/flexible ranged weapons like the crossbow and longbow.

Depictions of warfare in shows like Game of Thrones often have anachronisms like ballistas alongside trebuchets alongside longbows that conform to audiences' expectations. When the ballista was in vogue, castles and stone walls as we expect them to look in medieval times didn't exist, and it would have been firing against comparably softer fortifications.
posted by AndrewInDC at 7:59 AM on August 10, 2017 [16 favorites]

They were much smaller and portable than catapults or trebuchets. You could put them in towers or wagons as they do not create a large moment that would tip these things over. They could be easily operated by one person. They were also more repeatable, accurate and quicker than stone projectile devices, although they could be used for stones as well. They are better for taking out small buildings or wagons or carts, or hitting a target through an opening in a wall or tower.
posted by Short End Of A Wishbone at 8:10 AM on August 10, 2017 [2 favorites]

When the ballista was in vogue, castles and stone walls as we expect them to look in medieval times didn't exist, and it would have been firing against comparably softer fortifications.

Indeed. Roman legionnaire fortifications, for instance, largely consisted of earthen berms and wooden palisades. Only long-term military settlements would have used stone fortifications.
posted by tobascodagama at 8:38 AM on August 10, 2017 [1 favorite]

they were much smaller than the device on GoT for starters. Very long range and able to pierce shields and wooden fortifications. It the era of chariots and phalanx they were highly disruptive weapons.

Think of them more as a sniper rifle less as a cannon.

GoT is very anachronistic about tech, by example by the time the real world had glorious armor like we see in the show, it also had early firearms/cannon and other basic chemically powered weapons.
posted by French Fry at 8:42 AM on August 10, 2017 [8 favorites]