Sieges were the predominant form of warfare across the medieval world and siege methods and technology developed alongside improvements in defence. This book goes back to the original sources to present a comprehensive view of the whole subject, tracing links across continents and analysing the relationship with changes in the design of town and castle defences, and linking contemporary historical accounts with archaeological studies. It considers the most important questions raised by siege warfare: who designed, built and operated siege equipment? How did medieval commanders gain their knowledge? What were the roles of theoretical texts and the developing science of siege warfare? How did nomadic peoples acquire siege skills? Were castles and town walls built purely of a military purpose, or did they play a symbolic role also? The first volume begins in 450 AD with the replacement of the western Roman empire by barbarian successor states, but also examines the development of the Byzantine Empire, the Muslim Caliphate and its successors, and the links with China, through to the early thirteenth century. The second continues with the Mongol conquests in Asia and Europe and the thirteenth-century apogee of pre-gunpowder siege warfare, before examining the slow impact of guns and the cumulatively massive changes in attack and defence of the fifteenth century.