Skeleton 150 in his grave at Stirling Castle. (© Crown Copyright HES. Used with permission)

Some seven centuries ago, a man in Scotland had a terrible, horrible, no-good, very bad day indeed.There he was, going about the business of living, when something interrupted.Something that slammed into him from behind with such tremendous force that it shattered his skeleton in more than 160 places.Now, scientists think they know what hit him: a projectile hurled by a medieval siege engine.The most likely culprit? A trebuchet – a formidable weapon that used a falling counterweight to hurl heavy projectiles at enemy fortifications.If they're right, the young man's remains, known as Skeleton 150, represent the first known evidence of trebuchet trauma in the archaeological record."His death would, fortunately, have been essentially instantaneous," bioarchaeologist Dr Jo Buckberry of the University of Bradford in the UK told ScienceAlert."The worst fractures are to the back of the head on the right side, and the right shoulder, and these came from behind. While the left shoulder is also impacted, it is less fragmented, suggesting a slightly lower force there."A 3D reconstruction of Skeleton 150's skull reveals extensive fracturing. (Dr Jo Buckberry/University of Bradford, supplied)Stirling Castle sits atop a high crag in Stirling, overlooking the River Forth – a site strategically chosen for maximum visibility and minimum pregnability. It's been around since at least the early 12th century, the seat of many generations of Scottish monarchs.During the late 13th and early 14th centuries, it became both strategically important and a potent symbol in the Wars of Scottish Independence between Scotland and England – a rich prize the English wanted to take and the Scottish, understandably, wanted to keep.The battles over the castle were fierce and bloody, and it changed hands repeatedly as the wars dragged on. Skeleton 150 was one of several individuals whose remains are associated with this violent period of history.