The medieval period was one of the most inventive in military history when it came to non-gunpowder machine development. During this period, the pre-existing military-technological traditions from the ancient worlds were brought together. Three civilisations; Graeco-Roman World, Persia, India, and China, 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 that used assorted power sources from torsion ‘energy storage’ systems, to manpowered and counterbalance sling devices, rockets et al.