Shimizuyama Castle

In detail

Shimizuyama Castle was a long, narrow stronghold built in the late sixteenth century along the ridge of Mt. Shimizu above what is now the town of Izuhara. The fortress was likely intended to complement the defenses of Kaneishi Castle at the foot of the mountain in the event of a visit by the warlord Toyotomi Hideyoshi (1537–1598), who was planning to invade the Korean Peninsula at the time.

By the early 1590s, Hideyoshi had defeated all his domestic rivals and unified Japan, after which he planned the conquest of Ming China by way of Korea. The invasion forces were to depart from Iki and Tsushima, and Hideyoshi ordered his lieutenants to establish footholds on the islands to accommodate a force of 150,000. Each of these bases was to include a castle from which Hideyoshi could personally oversee the campaign. In Izuhara that would have been Kaneishi Castle, the stronghold of the So family, administrators of Tsushima.

Shimizuyama Castle was built to overlook Kaneishi Castle. It consisted of three enclosures built on flattened terraces—two along the mountain’s ridge and one on the 206-meter-high summit—and a connecting corridor that spanned a length of 500 meters. The terraces were reinforced with stone ramparts. The first and third enclosures have been relatively well preserved, and the ruins of their entrances and walls are clearly visible on the mountain. Both are accessible via a hiking trail that ascends to the third enclosure and follows the ridge from there. The site of the third enclosure (sannomaru), around 100 meters above sea level, provides a view over the modern town and port of Izuhara.