This legendary fortress city in Asia Minor had recently been a prized possession of Byzantine Emperor Alexius. Now that it was in their hands, the Turks were convinced that they were destined to take over the rest of the shrinking Byzantine Empire too. It was a kind of Moorish manifest destiny that even the Pope in Rome couldn’t seem to stop.
Pope Urban II was losing his mind over the fact that the Holy Land was under Muslim control. He practically screamed at everyone to kick them out. A bunch of enthusiastic peasants, led by a guy named Peter the Hermit, got so fired up that they set off on foot from northern France for a Christian crusade. They actually made it all the way to Asia Minor, but their luck ran out when they reached Nicaea.
Back in its prime, Nicaea had hosted two major ecumenical councils that shaped early Christian teachings. But unfortunately for Peter’s followers, the Turks weren’t interested in discussing theology. On November 21, 1096, a Turkish army caught up with Peter’s ragtag group at the Dracon passage and, in a brutal massacre, took them down without mercy.
Fast forward six months later, and the ground at the Dracon Passage was still scattered with their bleached bones. In May of 1097, a huge wave of Christian Crusaders showed up and laid siege to the city. The Turks inside felt secure behind Nicaea’s thick walls, thinking they could hold their ground against the Europeans. Little did they know, they were in for a shock. While they listened nervously, the sound of carpenters and engineers working on some serious weaponry filled the air as the Crusaders prepared for battle.
Out of nowhere, massive rocks were flying through the air, crashing into the city’s walls and towers, freaking everyone out. After taking down two Turkish relief groups in some brutal close combat, the Crusaders cranked up the horror even more. To the shock of those trapped inside, a bunch of severed heads started dropping onto the defenders of Nicaea. The Crusaders had chopped off the heads of the Turkish bodies piled up around the city and were now tossing them over the walls. By June 19, completely shaken by everything that had happened, the Turks gave up. They were so scared that they actually asked to hand the city back to the Byzantines instead of facing the terrifying Crusaders head-on. For the Turks at Nicaea, just dealing with the medieval catapult—the most powerful weapon from Europe—was already too much.
From Onager to Catapult
When it comes to siege weapons, the catapult (which comes from the Greek word “Katapultos,” meaning shield piercer) that scared the defenders of Nicaea was actually a pretty weak version of a much better and more precise ancient weapon called the onager. This Roman invention was made entirely of wood and had a four-wheeled base with a long arm and a big sling at the end.
The throwing arm of the onager was sandwiched between thick ropes that were twisted together to create a lot of rotational force. They used a winch and ratchet to tighten the ropes, and then a windlass (plus some serious muscle) pulled the arm back until it was almost parallel to the ground. Once it was locked in place with a slip hook, they loaded the sling—usually with a hefty rock. When they released the slip hook, the energy burst sent the arm flying back up while the sling launched the projectile toward its target. The name “onager” actually means donkey in Latin, which is fitting because the device would often kick up its back end when fired.
After the Roman Empire fell and the Dark Ages rolled in, the glory days of the onager came to a sudden stop. It wasn’t until the early Middle Ages that European feudal lords tried to bring back this technology, inspired by the ancients. Unfortunately, they couldn’t make ropes as strong and durable as the Romans did. Their ropes, made from tightly wound leather, animal hair, or hemp called skeins, were super sensitive to moisture. If they got wet—even just a little—they would loosen up and render the whole machine useless. This was a major headache not only in the rainy weather of Western Europe but also in the Middle East, where Crusader armies often found their siege engines completely out of commission after an unexpected rainstorm.
In this illustration from the 13th century, you can see a trebuchet attacking the fortress at Acre during the Third Crusade. One big issue with this medieval weapon was that it needed a lot of upkeep. You had to have a skilled technician around to keep tightening the ropes and making sure everything was balanced so it could hit its target. Doing that would be tough enough in peaceful times, but trying to do it in the chaos of battle? Even trickier! Plus, if the soldier operating the machine got hurt or killed, there might not be anyone else around who knew how to fix it, which would take the weapon out of commission. On top of that, they switched out the sling at the end of the arm for a much crappier wooden scoop, which messed up its accuracy. Because of all this, the onager from the early medieval days, also called a mangonel (or nag), didn’t really hold up well compared to other weapons. Still, it did leave us with a bit of a legacy: the term “mangonel” comes from the Latin word for war engine, and it was often called the “gonne,” which is where we get the modern word “gun.”
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The Trebuchet
So, back in the late 12th century, during the peak of the Crusades, medieval military engineering really leveled up with the creation of the trebuchet, a kind of counterweight siege weapon. While it’s thought that the Chinese might have come up with a smaller version of it way back in 300 BC, the exact origins of the medieval trebuchet are still a bit of a mystery. The term “trebuchet” comes from the Old French word “trabucher,” which means to tip over or fall.
The way trebuchets worked was pretty cool – they were like giant seesaws. They had a big wooden frame, and the throwing arm was attached so it could pivot about a quarter of the way down. On the shorter end, there was a heavy counterweight that could weigh up to 10 tons. The longer end had a sling attached to it. When you pulled the long end down, it lifted the counterweight high up. Once everything was set, the sling was stretched out, and a hefty projectile (often a stone weighing over 300 pounds) was placed inside. When the counterweight dropped, the arm shot up with a ton of force, launching the stone in a big arc towards its target.
With that kind of power, it wasn’t uncommon for castle walls to be smashed down in just one shot. For example, during the Crusaders’ attack on Acre in 1191, a massive trebuchet called “Bad Neighbor” wrecked large sections of the city walls with each hit. The defenders of Castle Naudry faced a similar fate when the Occitanians laid siege to them in 1211. They recorded their experience, noting how the first shot took down a tower, the second destroyed a chamber right in front of everyone, and by the third shot, the stone shattered but not before causing serious injuries to those inside the town.The most legendary trebuchet has to be the gigantic siege weapon called the Warwolf, which was used to crush the Scots during the siege of Stirling Castle back in 1304. Legend has it that King Edward I of England had 50 carpenters working around the clock to build this beast, and when they were done, they basically created the medieval version of a hydrogen bomb.
Now, let’s talk about how these bad boys worked. The early trebuchets either had a fixed counterweight or one that could pivot, but later models featured a counterweight that could slide up and down the arm. This allowed the operator to tweak the range. The trajectory depended mainly on how heavy the projectile was and the angle at which it was released from the arm. If you changed the weight of what you were launching, you’d change the trajectory too. So, the crew was always fiddling with the release angle or the sling length. A shorter sling meant the arm swung faster, leading to a higher launch, while a longer sling slowed things down, resulting in a flatter shot.
However, there were some downsides. These machines had a slow firing rate and weren’t exactly mobile. They were so huge and heavy that you couldn’t move them easily, so they had to be built right where the siege was happening. To solve this, smaller versions called traction trebuchets were created. These used lighter projectiles that could take out rows of archers. Instead of heavy counterweights, they relied on a team of up to 12 guys pulling ropes attached to the throwing arm. This made them quicker to fire and easier to transport, kind of like how modern artillery works.Back in the day, when things were peaceful, trebuchets were used to toss roses at the ladies during tournaments. But their more notorious use was definitely what went down at Nicaea. As a weapon of fear, they were unbeatable. They didn’t just launch severed heads; they also flung hostages, captured prisoners, useless negotiators, lepers, plague victims, dead bodies, sick animal remains, barrels of poop, and all sorts of creepy crawlies over castle or city walls to force surrender.
Trebuchets became such a staple in warfare that they stuck around for centuries, only fading out when cannons powered by gunpowder took over. The last time they were used was in 1521 in the New World, when Spanish conquistadors led by Hernan Cortes laid siege to the Aztec capital of Tenochtitlan, which is now Mexico City.
