Torsion siege engine

A torsion siege engine is a type of siege engine that utilizes torsion to launch projectiles. They were initially developed by the ancient Macedonians, specifically Philip II of Macedon and Alexander the Great, and used through the Middle Ages until the development of gunpowder artillery in the 14th century rendered them obsolete. Greek and Roman artillery Preceding the development of torsion siege engines were tension siege engines that had existed since at least the beginning of the 4th century BC, most notably the gastraphetes in Heron of Alexandria's Belopoeica that was probably invented in Syracuse by Dionysius the Elder. Though simple torsion devices could have been developed earlier, the first extant evidence of a torsion siege engine comes from the Chalcotheca, the arsenal on the Acropolis in Athens, and dates to c. 338 - 326 BC. It lists the building's inventory that included torsion catapults and its components such as hair springs, catapult bases, and bolts. The transition from tension machines to torsion machines is a mystery, though E.W. Marsden speculates that a reasonable transition would involve the recognition of the properties of sinew in previously existing tension devices and other bows. Torsion based weaponry offered much greater efficiency over tension based weaponry. Traditional historiography puts the speculative date of the invention of two-armed torsion machines during the reign of Philip II of Macedon circa 340 BC, which is not unreasonable given the earliest surviving evidence of siege engines stated above. The machines quickly spread throughout the ancient Mediterranean, with schools and contests emerging at the end of the 4th century BC that promoted the refinement of machine design. They were so popular in ancient Greece and Rome that competitions were often held. Students from Samos, Ceos, Cyanae, and especially Rhodes were highly sought after by military leaders for their catapult construction. Torsion machines in particular were used heavily in military campaigns.