Christopher Duffy 
Siege Warfare [PDF ebook] 
The Fortress in the Early Modern World 1494-1660

This classic text is the first integrated survey of the phenomenon of siege warfare during its most creative period. Duffy demonstrates the implications of the fortress for questions of military organization, strategy, geography, law, architectural values, town life and symbolism and imagination. The book is well illustrated, and will be a valuable companion for enthusiasts of military and architectural history, as well as the general medievalist.