How Do Trebuchets Work?

collection of siege engines the world had ever seen. Edward had ordered all Scottish churches stripped of their lead, which was used to build powerful catapults called trebishes, the largest of which could hurl boulders weighing over three hundred pounds that's over a hundred and forty kilos. The greatest of edwards trebishes was christened Ludgar, or the war Wolf. The war Wolf required five master carpenters and fifty workmen to build, and was so terrifying in scale that Oliphant had no

choice but to surrender. But not so fast, said Edward. He wanted to fire the war Wolf first, and even built a special viewing platform so ladies of his court would have a good view of the destruction it wrought. But we spoke with William Gerstell, a science journalist and author of the Art of the Catapult. He explained, Edward almost bankrupted himself building all these trebishes, and by God he was going to use them in a theatrical display

of domination. Edward pulled the trigger on the war Wolf, sending its massive projectile arching through the sky and crashing through the castle's twelve ft thick walls. That's about three and a half meters of stone. The rebellion was officially over, and Edward had earned himself a new nickname, the Hammer

of the Scots. Before gunpowder was popularized in the mid fourteenth century, there were no cannons to launch heavy lead balls through enemies and their walls, but that didn't stop creative warfarers from devising ways to toss stuff at each other. One of the most effective was the catapult, a device that uses a spring loaded arm or a heavy counterweight to hurl large objects over great distances. There are three

general types of catapults. The first, called a ballista or tension catapult, looks like an oversized crossbow and works on the same principles generating force from the tension of the bow arms. The ballista was invented by the Greeks around three b c E. The second, known as the monitor or torsion catapult, gets its power from a ropelike bundle of animal sinew and hair. The rope is twisted tightly to create torsion, which when released, generates enough force to

launch a small projectile from a catapult arm. The Romans named the monitor after a wild donkey that delivered an especially strong kick. The third type of catapult is the trebishe, perhaps the simplest yet most powerful catapult of all. The arm of a trebishe is actually a long lever that swung into motion by pulling downward with ropes or dropping

a heavy counterweight. While trebishe is a French word, the technology is believed to have originated in China in the first couple of centuries c. The very earliest trebishes, unlike those first used in China and later in Europe in the early Middle Ages, were people powered, meaning the lever arm of the catapult was swung by a group of soldiers pulling on a rope. But the real innovation in trebische technology came in the twelfth century with the advent

of the counterweight trebische. We also spoke with Michael Fulton, a history professor at Langara College in British Columbia an author of siege warfare during the Crusades. He explained that an elevated basket is weighted with hundreds or even thousands of pounds of rocks. That's the counterweight. When the basket is dropped, it pulls down on a rope connected to the short end of a long lever arm that swings on an axle. He said, as the short end of the lever is pulled down, the long end rises at

a proportionally light or rate. When you add a sling at the end of the arm, you force the projectile to travel even farther during the same amount of time, which adds to your rate of acceleration. It's all really basic physics at a fundamental level. Gristell has built plenty of trebiches, including a d I Y design using wood and PVC that he named Little Ludgar after Edwards Trebiche. He said, the longer that lever and the heavier the weight,

the farther the projectile goes. He noted that the counterweight has to weigh approximately a hundred times the object you're trying to throw. Gerstell once made a trebiche with a five pound or two hundred and twenty seven kilo counterweight that was still only powerful enough to launch a small cantelope. During the Middle Ages, the construction of fortified cities led

to a new type of military campaign, the siege. Laying siege to a walled city required new war machines like battering rams for splintering thick doors and siege towers for reaching high balls, but one of the earliest and most powerful innovations was the trebishe. One of the first recorded uses of a trebische in battle was during the siege

of Thessalonica in the late sixth century CE. Thessalonica was a Byzantine stronghold under attacked by the Avars, a collection of Central Asian tribes who used a people powered trebische that was likely inspired by ancient Chinese weaponry. But those primitive traction trebisches could only launch small projectiles and functioned as anti personnel weapons, not castle killers. Fulton explained traction trebishes were like an archer on steroids. You're definitely not

smashing down solid walls in the early Middle Ages. That would happen in the thirteenth century, when counterweight trebishes were being built at larger and larger scales all across Europe. Those truly massive trebisches would be constructed off site and then assembled on the battlefield itself. While a counterweight trebisch a could toss a boulder over a castle wall, there were definitely trade offs. For one, it took a really

long time to reload the counterweight. Fulton says that the smaller traction trebishes could fire up to four shots a minute, while the biggest trebishes were lucky to get off one shot every half hour. Catapults and trebishes were not limited to firing conventional projectiles like stones and lead balls. According to one Lurid fourteenth century account, the Mongols used their catapults to launch plague written corpses, an early type of bioweapon,

into a medieval city in modern day Ukraine. Other stories tell of dead horses being slung by trebishe over castle walls to sicken the enemy with the stench. But Fulton, who has witnessed the forces unleashed during the throwing sequence of a large Trebishe is skeptical about the accuracy of such accounts. He said, if you try to put something organic into one of those slings, chances are it's going to be ripped apart before you can throw it effectively.

Fulton has more confidence in the hals of human heads being logged back and forth by trebisches at the siege of Nicia in ten during the First Crusade. He said that was more psychological than biological. And when it comes to incendiary weapons like Greek fire, which was a sort of early napalm that involved pine tar, sulfur and naturally occurring petroleum, but the recipe for which is lost, Fulton says that he doubts that Edward or anyone else was

launching Greek fire bombs from trebises with any regularity. It was more likely that castle defenders would try to fire incendiaries at the trebishe to burn the weapon to the ground. Though even if edwards legendary trebisch only launched rocks, there simply was no siege weapon that was as terrifying to the enemy and as entertaining to the troops. Fulton said at a fundamental level, You're not going to build these engines unless they have value, But there is value in

that intimidation factor. In general, kings like to have big things they can show off. Today's episode was written by Dave Ruse and produced by Tyler Clang. For more on this and lots of other topics, visit how stuff works dot com. Brain Stuff is production of iHeart Radio. Or more podcasts from my heart Radio visit the i heart Radio app, Apple Podcasts, or wherever you listen to your favorite shows.