The first proper fortifications in Japan began to develop with the appearance of the first emperors around 250. Although initially fortifications were simply wooden constructions, as internal strife became a way of life in Japan, more and increasingly elaborate fortifications were built. This book not only studies the entire period of Japanese castle development from the very first fortifications, through to the sophisticated structures of the 16th and 17th century and beyond to the 19th century, but also covers the castles built to control Korea during the brief samurai invasion in the late 16th century and the development of fortified temples and monasteries in Japan.