Ballista

A large ancient siege weapon that used twisted cords to store torsional energy and launch heavy bolts or stones at distant targets.

Torsion siege engine: A siege weapon that stores energy by twisting cords or sinew to propel a projectile. The ballista is one of the most recognizable weapons in this broader mechanical family.
Gastraphetes: An ancient Greek belly-bow that used a sliding stock and mechanical tensioning to launch arrows. It is an early mechanical predecessor in the development of Greek artillery.
Siege warfare: Military operations to capture or defend fortified places through investment, assault, or bombardment. Ballistae supported attacks on fortifications and helped defenders keep attackers at distance.
Catapult: A device that launches a projectile using stored mechanical energy. The ballista belongs to the broader family of projectile-throwing machines.
Torsion spring: An elastic element that stores energy when twisted and releases it as torque. Twisted skeins supplied the stored energy that drove the ballista’s arms.
Dionysius I of Syracuse: The ruler of Syracuse from 405 to 367 BCE, who expanded the city’s military power and siege technology. His military workshops are associated with the early development of Greek siege artillery.
Roman legion: The principal military unit of the Roman Republic and Empire, composed of several thousand soldiers. Legions deployed artillery as part of organized field operations and siege trains.
Mangonel: A medieval traction or counterweight-powered engine that hurled stones from a throwing arm. Its throwing arm and later power systems differ from the ballista’s torsion-driven paired arms.
Sinew: Strong connective tissue made of collagen fibers, historically used in bows and torsion engines. Sinew was among the materials used to make resilient torsion bundles.
Philo of Byzantium: A Greek engineer and writer whose surviving work describes ancient mechanical and military technology. His technical writing preserves evidence about the design tradition behind torsion artillery.

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