Revolutionizing Castles: Nobunaga’s Vision in Warriors Building Castles

The concept of castle changed with Nobunaga.

“Castles” are popular. There was a time when it was referred to as a trend, but events like the “Castle EXPO,” held annually in Yokohama, draw nearly 20,000 fans, showcasing its enduring appeal. Numerous books about castles have been published, most of which focus on the structures of fortifications, making them somewhat inaccessible to beginners. Historian Atsushi Kawai has released a book titled “Warlords Build Castles” (Poplar Shinsho), which takes a unique approach by discussing the charm of castles from the perspective of the warlords who built them. What were the thoughts behind the construction of these castles? What kind of warlords were considered masters of castle building? I spoke with Kawai.

Since ancient times, structures resembling castles have existed to protect living spaces, such as the moated settlements of the Yayoi period. In ancient times, there were also water castles in Dazaifu and mountain castles (Korean-style), and the residences of armed samurai can be considered, in a sense, castles. During the Nanboku-chō period of unrest, many mountain castles were built throughout the country, and during the Sengoku period, various daimyō constructed numerous fortifications within their territories. However, a person who significantly changed the concept of castle during the late Sengoku period was Oda Nobunaga. The characteristics of castles that began with Nobunaga and were inherited by Toyotomi Hideyoshi are said to be threefold.

“Firstly, the impressive stone walls, exemplified by Azuchi Castle, were constructed entirely of stone. Secondly, when building structures, they shifted from using post-and-beam construction to using large foundation stones to support the pillars. Thirdly, while buildings were previously thatched with reeds, they transitioned to tiled roofs.

On the other hand, some experts argue that Nobunaga was revolutionary in that the main keep and his residence were placed at the top of a hierarchical arrangement of his retainers’ houses. In any case, it’s undeniable that Nobunaga had a significant impact on the history of castles.”