Following the Battle of Sekigahara in 1600, Horio Yoshiharu and his son Tadauji were allocated Izumo and Oki domains. At first, they based themselves in Gassantoda Castle, however, the mountain castle was considered too far east to effectively control the new domain, so construction of a new castle in Matsue, a major land and water transportation hub central to their territory, was planned. Matsue was started in 1607 and completed over four years. The 28.4m high Mt. Kameda was chosen as it was surrounded by natural defenses including the Ohashi River and Lake Shinji to the south, and muddy fields and marshes to the east and north. The only surviving tenshu in Japan’s far western San’in region, the four level, fi ve-story tenshu was constructed with warfare in mind and features 94 covered sama gun-port hatches around the walls, and a water well inside the tenshu basement in case of attack. In 2012, the traditional dated invocation plaque offered on completion was rediscovered and Matsue was designated the fifth National Treasure keep.