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Meet the only known trebuchet casualty in history
“It highlights the brutality of medieval warfare,” said paleopathologist Jo Buckberry.
During a medieval siege, a trebuchet scored a chance hit on an unlucky defender. A small boulder slammed into his upper back at close to 300 kilometers an hour, smashing bones and crushing him beneath its weight.
The man’s skeleton lay beneath the chapel of Scotland’s Stirling Castle, along with the remains of several other people who had clearly died violent deaths. But this one, known to us only as Skeleton 150 (or as “trebuchet guy” in your faithful correspondent’s notes), stood out even among that battle-damaged crowd because most of his upper body had been shattered. According to University of Bradford paleopathologist Jo Buckberry, who presented her research at the 25th European Meeting of the Paleopathology Association last week, Skeleton 150 is the only known trebuchet casualty in history.
Skeleton 150 was in terrible shape, even for a dead guy. The man’s skull had broken in 61 separate places, and another 60 jagged bits of bone were distributed across his ribs. His right shoulder was broken, and his right leg above the knee was basically shattered.
Buckberry and her colleagues threw everything they could, metaphorically speaking, at the jigsaw puzzle of broken bones: forensics, microscopes, X-rays, and micro-CT scans. All of those results pointed to a single moment of crushing impact by something heavy and fast-moving. The pattern of the injuries suggests that the man’s right shoulder and the back of his head caught the brunt of the impact, while his ribs probably cracked under the weight of something heavy slamming him into the ground and pinning him there.
The bones had broken when they were fresh, so it was clearly not a case of “oops, we dropped a big rock on the corpse.” And the amount of force required to do so much damage in a single, shattering blow ruled out several messy possible ways to die during a medieval siege: Skeleton 150 hadn’t been trampled by a horse or run over by a cart, for example. Even if he had fallen from the castle walls, he probably wouldn’t have landed with enough force to do all of that, and the angle would have been all wrong.
“The most similar cases I was finding were car crashes and people hit by trains,” Buckberry told Science.org’s Andrew Curry. Assuming Stirling Castle hadn’t been attacked by time travelers, though, that raised new questions. “What is large and moving very quickly in 1304?”
A trebuchet works a bit like the world’s deadliest seesaw; at the long end of the seesaw is the sling that holds the projectile, and at the shorter end is a counterweight (a box of rocks or lead, 10 to 100 times heavier than the projectile). When the counterweight drops, its momentum raises the other end of the seesaw, tossing the sling up in a big arc. And when the sling reaches the end of its length, it stops—but the projectile keeps flying until it hits something.
A typical trebuchet of the time could launch a 90-kilogram projectile (typically a big rock) a few hundred yards. According to this handy medieval trebuchet calculator, that means the projectile would have smashed into Skeleton 150 at somewhere between 200 and 300 kilometers per hour, depending on the exact weight of the projectile and the trebuchet’s counterweight, the length of the sling, and the airspeed velocity of an unladen swallow. That’s an impact with a little over 200 kilojoules of energy.
Trebuchets and other siege engines (we will, under no circumstances, be delving into the distinctions between the different types of catapults) were meant to take out walls and other fortifications. They weren’t anti-personnel weapons; people undoubtedly got injured by flying debris or collapsing structures, but medieval engineers weren’t aiming their catapults at individuals. Skeleton 150 just got terribly unlucky.