When it came to non-gunpowder machine development, the medieval period was one of the most inventive in military history. During this era, the pre-existing military-technological traditions from the ancient worlds were brought together. Three civilisations were primarily responsible for this evolution: the Late-Roman or Byzantine Empire, the Islamic World, and latterly the Mongol ‘World Empire’. This book examines the resulting stone-throwing machines from torsion ‘energy storage’ systems, to manpowered and counterbalance sling devices, rockets and others.