Know your siege engines

From Brian K. Davison.  The New Observer's Book of Castles.  Frederick Warne, 1979, 1986.  Line drawings by Jasper Dimond.

Ballistas shot long iron darts, and so were effectively an anti-personnel weapon.  The mangonel was a catapult that flung rocks and other heavy objects to break gates and walls.  It's power originated in a twisted skein of rope, whose effectiveness varied with humidity, making it an inaccurate weapon.  The trebuchet was the howitzer of its day, capable of hurling stones of 150 kg at least 100 meters.  A large trebuchet could throw a dead horse.  Technically, mangonels and trebuchets were classified as petraria (stone throwers) but in battle they enjoyed names such as Malvoisin, meaning "bad neighbour."