The Ballista

The ballista belongs to the catapult family, like the trebuchet, and dates from the 12th century. It consists of a lever arm with a receptacle at the end that holds the projectiles. It was operated by pulling on the end of the lever arm, with traction being facilitated by the addition of a counterweight. This formidable device was thus able to project one 10 to 30 kg boulder a minute.

This ballista could have fired rocks, rotting carcasses or Greek fire. Greek fire was a mixture of saltpetre, sulphur, resin and other fusible materials that would stick to objects and burn them, and was much feared in the Middle Ages. Water was unable to extinguish it and only sand or wet earth had any effect. Large ballistae were assembled and disassembled on site. Some were developed to fire arrows.