WEBVTT - How Do Trebuchets Work? 0:00:01.920 --> 0:00:06.640 Welcome to Brainstuff, a production of iHeart Radio, Hey brain 0:00:06.680 --> 0:00:11.320 Stuff Lauren Vogelbaum. Here. In the year thirteen o four CE, 0:00:11.440 --> 0:00:15.200 King Edward, the First of England, laid siege to Sterling Castle, 0:00:15.600 --> 0:00:19.240 home of the last holdouts of a Scottish rebellion. Behind 0:00:19.280 --> 0:00:22.720 the castle's thick walls, Sir William Oliphant and his Scottish 0:00:22.720 --> 0:00:26.920 loyalists endured months of aerial bombardment from perhaps the greatest 0:00:26.960 --> 0:00:30.760 collection of siege engines the world had ever seen. Edward 0:00:30.800 --> 0:00:34.160 had ordered all Scottish churches stripped of their lead, which 0:00:34.200 --> 0:00:37.640 was used to build powerful catapults called trebishes, the largest 0:00:37.680 --> 0:00:40.320 of which could hurl boulders weighing over three hundred pounds 0:00:40.440 --> 0:00:43.800 that's over a hundred and forty kilos. The greatest of 0:00:43.880 --> 0:00:48.920 edwards trebishes was christened Ludgar, or the war Wolf. The 0:00:48.960 --> 0:00:53.000 war Wolf required five master carpenters and fifty workmen to build, 0:00:53.360 --> 0:00:56.280 and was so terrifying in scale that Oliphant had no 0:00:56.440 --> 0:01:00.000 choice but to surrender. But not so fast, said Edward. 0:01:00.360 --> 0:01:03.440 He wanted to fire the war Wolf first, and even 0:01:03.480 --> 0:01:06.360 built a special viewing platform so ladies of his court 0:01:06.480 --> 0:01:08.919 would have a good view of the destruction it wrought. 0:01:10.200 --> 0:01:13.240 But we spoke with William Gerstell, a science journalist and 0:01:13.319 --> 0:01:17.080 author of the Art of the Catapult. He explained, Edward 0:01:17.120 --> 0:01:20.559 almost bankrupted himself building all these trebishes, and by God 0:01:20.640 --> 0:01:24.560 he was going to use them in a theatrical display 0:01:24.560 --> 0:01:27.319 of domination. Edward pulled the trigger on the war Wolf, 0:01:27.720 --> 0:01:31.240 sending its massive projectile arching through the sky and crashing 0:01:31.319 --> 0:01:34.039 through the castle's twelve ft thick walls. That's about three 0:01:34.080 --> 0:01:37.880 and a half meters of stone. The rebellion was officially over, 0:01:38.319 --> 0:01:41.319 and Edward had earned himself a new nickname, the Hammer 0:01:41.480 --> 0:01:45.800 of the Scots. Before gunpowder was popularized in the mid 0:01:45.840 --> 0:01:49.480 fourteenth century, there were no cannons to launch heavy lead 0:01:49.480 --> 0:01:53.279 balls through enemies and their walls, but that didn't stop 0:01:53.360 --> 0:01:57.000 creative warfarers from devising ways to toss stuff at each other. 0:01:57.840 --> 0:02:00.920 One of the most effective was the catapult, a device 0:02:01.000 --> 0:02:03.880 that uses a spring loaded arm or a heavy counterweight 0:02:04.080 --> 0:02:08.240 to hurl large objects over great distances. There are three 0:02:08.280 --> 0:02:11.840 general types of catapults. The first, called a ballista or 0:02:11.919 --> 0:02:15.760 tension catapult, looks like an oversized crossbow and works on 0:02:15.800 --> 0:02:18.720 the same principles generating force from the tension of the 0:02:18.760 --> 0:02:21.960 bow arms. The ballista was invented by the Greeks around 0:02:22.040 --> 0:02:26.840 three b c E. The second, known as the monitor 0:02:27.200 --> 0:02:30.639 or torsion catapult, gets its power from a ropelike bundle 0:02:30.720 --> 0:02:34.200 of animal sinew and hair. The rope is twisted tightly 0:02:34.280 --> 0:02:38.040 to create torsion, which when released, generates enough force to 0:02:38.200 --> 0:02:42.120 launch a small projectile from a catapult arm. The Romans 0:02:42.200 --> 0:02:45.200 named the monitor after a wild donkey that delivered an 0:02:45.320 --> 0:02:50.520 especially strong kick. The third type of catapult is the trebishe, 0:02:50.720 --> 0:02:54.160 perhaps the simplest yet most powerful catapult of all. The 0:02:54.320 --> 0:02:57.600 arm of a trebishe is actually a long lever that 0:02:57.760 --> 0:03:00.960 swung into motion by pulling downward with ropes or dropping 0:03:00.960 --> 0:03:04.560 a heavy counterweight. While trebishe is a French word, the 0:03:04.600 --> 0:03:07.400 technology is believed to have originated in China in the 0:03:07.400 --> 0:03:12.360 first couple of centuries c. The very earliest trebishes, unlike 0:03:12.440 --> 0:03:14.519 those first used in China and later in Europe in 0:03:14.560 --> 0:03:18.040 the early Middle Ages, were people powered, meaning the lever 0:03:18.200 --> 0:03:20.280 arm of the catapult was swung by a group of 0:03:20.320 --> 0:03:23.840 soldiers pulling on a rope. But the real innovation in 0:03:23.880 --> 0:03:27.280 trebische technology came in the twelfth century with the advent 0:03:27.360 --> 0:03:31.400 of the counterweight trebische. We also spoke with Michael Fulton, 0:03:31.560 --> 0:03:34.840 a history professor at Langara College in British Columbia an 0:03:34.920 --> 0:03:39.360 author of siege warfare during the Crusades. He explained that 0:03:39.440 --> 0:03:43.080 an elevated basket is weighted with hundreds or even thousands 0:03:43.080 --> 0:03:46.960 of pounds of rocks. That's the counterweight. When the basket 0:03:47.040 --> 0:03:49.760 is dropped, it pulls down on a rope connected to 0:03:49.760 --> 0:03:52.480 the short end of a long lever arm that swings 0:03:52.520 --> 0:03:56.040 on an axle. He said, as the short end of 0:03:56.040 --> 0:03:59.080 the lever is pulled down, the long end rises at 0:03:59.080 --> 0:04:02.160 a proportionally light or rate. When you add a sling 0:04:02.240 --> 0:04:04.400 at the end of the arm, you force the projectile 0:04:04.480 --> 0:04:07.160 to travel even farther during the same amount of time, 0:04:07.400 --> 0:04:10.760 which adds to your rate of acceleration. It's all really 0:04:10.760 --> 0:04:15.560 basic physics at a fundamental level. Gristell has built plenty 0:04:15.560 --> 0:04:18.599 of trebiches, including a d I Y design using wood 0:04:18.600 --> 0:04:22.279 and PVC that he named Little Ludgar after Edwards Trebiche. 0:04:23.040 --> 0:04:26.160 He said, the longer that lever and the heavier the weight, 0:04:26.480 --> 0:04:30.359 the farther the projectile goes. He noted that the counterweight 0:04:30.400 --> 0:04:33.360 has to weigh approximately a hundred times the object you're 0:04:33.360 --> 0:04:36.599 trying to throw. Gerstell once made a trebiche with a 0:04:36.600 --> 0:04:39.720 five pound or two hundred and twenty seven kilo counterweight 0:04:39.960 --> 0:04:43.600 that was still only powerful enough to launch a small cantelope. 0:04:45.320 --> 0:04:48.279 During the Middle Ages, the construction of fortified cities led 0:04:48.320 --> 0:04:52.080 to a new type of military campaign, the siege. Laying 0:04:52.120 --> 0:04:55.120 siege to a walled city required new war machines like 0:04:55.200 --> 0:04:59.040 battering rams for splintering thick doors and siege towers for 0:04:59.240 --> 0:05:02.680 reaching high balls, but one of the earliest and most 0:05:02.680 --> 0:05:07.160 powerful innovations was the trebishe. One of the first recorded 0:05:07.240 --> 0:05:09.679 uses of a trebische in battle was during the siege 0:05:09.680 --> 0:05:13.680 of Thessalonica in the late sixth century CE. Thessalonica was 0:05:13.720 --> 0:05:17.359 a Byzantine stronghold under attacked by the Avars, a collection 0:05:17.400 --> 0:05:20.400 of Central Asian tribes who used a people powered trebische 0:05:20.640 --> 0:05:24.960 that was likely inspired by ancient Chinese weaponry. But those 0:05:25.000 --> 0:05:29.280 primitive traction trebisches could only launch small projectiles and functioned 0:05:29.279 --> 0:05:34.359 as anti personnel weapons, not castle killers. Fulton explained traction 0:05:34.360 --> 0:05:37.760 trebishes were like an archer on steroids. You're definitely not 0:05:37.839 --> 0:05:42.039 smashing down solid walls in the early Middle Ages. That 0:05:42.200 --> 0:05:45.560 would happen in the thirteenth century, when counterweight trebishes were 0:05:45.600 --> 0:05:48.599 being built at larger and larger scales all across Europe. 0:05:49.680 --> 0:05:53.160 Those truly massive trebisches would be constructed off site and 0:05:53.200 --> 0:05:56.920 then assembled on the battlefield itself. While a counterweight trebisch 0:05:56.960 --> 0:05:59.560 a could toss a boulder over a castle wall, there 0:05:59.600 --> 0:06:02.960 were definitely trade offs. For one, it took a really 0:06:03.000 --> 0:06:06.919 long time to reload the counterweight. Fulton says that the 0:06:06.960 --> 0:06:10.360 smaller traction trebishes could fire up to four shots a minute, 0:06:10.720 --> 0:06:13.160 while the biggest trebishes were lucky to get off one 0:06:13.200 --> 0:06:18.320 shot every half hour. Catapults and trebishes were not limited 0:06:18.360 --> 0:06:23.080 to firing conventional projectiles like stones and lead balls. According 0:06:23.080 --> 0:06:26.680 to one Lurid fourteenth century account, the Mongols used their 0:06:26.720 --> 0:06:30.400 catapults to launch plague written corpses, an early type of bioweapon, 0:06:30.640 --> 0:06:34.520 into a medieval city in modern day Ukraine. Other stories 0:06:34.560 --> 0:06:37.480 tell of dead horses being slung by trebishe over castle 0:06:37.520 --> 0:06:41.400 walls to sicken the enemy with the stench. But Fulton, 0:06:41.560 --> 0:06:44.640 who has witnessed the forces unleashed during the throwing sequence 0:06:44.640 --> 0:06:47.800 of a large Trebishe is skeptical about the accuracy of 0:06:47.800 --> 0:06:51.080 such accounts. He said, if you try to put something 0:06:51.200 --> 0:06:54.280 organic into one of those slings, chances are it's going 0:06:54.320 --> 0:06:56.960 to be ripped apart before you can throw it effectively. 0:06:58.480 --> 0:07:01.080 Fulton has more confidence in the hals of human heads 0:07:01.120 --> 0:07:03.560 being logged back and forth by trebisches at the siege 0:07:03.560 --> 0:07:07.760 of Nicia in ten during the First Crusade. He said 0:07:08.279 --> 0:07:12.920 that was more psychological than biological. And when it comes 0:07:12.920 --> 0:07:16.080 to incendiary weapons like Greek fire, which was a sort 0:07:16.120 --> 0:07:19.320 of early napalm that involved pine tar, sulfur and naturally 0:07:19.320 --> 0:07:22.960 occurring petroleum, but the recipe for which is lost, Fulton 0:07:23.080 --> 0:07:25.880 says that he doubts that Edward or anyone else was 0:07:25.960 --> 0:07:30.000 launching Greek fire bombs from trebises with any regularity. It 0:07:30.120 --> 0:07:32.440 was more likely that castle defenders would try to fire 0:07:32.480 --> 0:07:35.480 incendiaries at the trebishe to burn the weapon to the ground. 0:07:37.080 --> 0:07:41.120 Though even if edwards legendary trebisch only launched rocks, there 0:07:41.240 --> 0:07:44.320 simply was no siege weapon that was as terrifying to 0:07:44.360 --> 0:07:48.560 the enemy and as entertaining to the troops. Fulton said 0:07:49.040 --> 0:07:51.480 at a fundamental level, You're not going to build these 0:07:51.520 --> 0:07:54.600 engines unless they have value, But there is value in 0:07:54.640 --> 0:07:58.440 that intimidation factor. In general, kings like to have big 0:07:58.440 --> 0:08:06.200 things they can show off. Today's episode was written by 0:08:06.280 --> 0:08:08.800 Dave Ruse and produced by Tyler Clang. For more on 0:08:08.800 --> 0:08:10.760 this and lots of other topics, visit how stuff works 0:08:10.800 --> 0:08:13.600 dot com. Brain Stuff is production of iHeart Radio. Or 0:08:13.600 --> 0:08:15.600 more podcasts from my heart Radio visit the i heart 0:08:15.640 --> 0:08:18.160 Radio app, Apple Podcasts, or wherever you listen to your 0:08:18.160 --> 0:08:18.840 favorite shows.