Book excerpt: The necessity to defend territory from strong points has been a fact of life since mankind first settled into agricultural communities. Sidney Toy traces the development of the art of fortification from the period of earliest historical examples down to the forts designed for defense by artillery, noting the salient features of the military works as well as the siege operations mounted against them. The castle is considered in its military aspect, as a fortress, and its domestic arrangements only in so far as they are ancillary to its function as a fortification and are necessary in its residence. This book is a product of a lifetime of travel, exploration and architectural study. The author himself surveyed most of the places described, and has drawn clear and fascinating ground maps and cross sections. There are also 200 superb photographs, maps and plans.