Site of Kikuchi Castle
Kikuchi Castle was a large hilltop fort built by the Yamato court in the late seventh century as part of a network of fortifications established to protect Japan from invasion by Tang China and the kingdom of Silla on the Korean Peninsula. Far from any potential front lines, the fort is thought to have been a supply base and training facility from which materials and manpower could be drawn in times of need. The garrison may also have been used to guard against the Hayato people of southern Kyushu, who resisted Yamato rule until the early eighth century.
The Yamato court feared an imminent attack from the continent after the year 663, when the Tang-Silla alliance subjugated the Korean kingdom of Baekje, a longtime Yamato ally, leaving Japan exposed to the might of Tang China. Baekje officers and engineers who had fled across the Sea of Japan were recruited to construct Korean-style forts in Kyushu and along the shores of the Seto Inland Sea—the likely route the enemy would take toward the capital of Asuka (present-day Nara Prefecture).
Kikuchi Castle was one of the strongholds designed with earthen and stone walls by Baekje refugees. It overlooked the fertile Kikuchi Plain, from which large quantities of food and other supplies could be sourced to be stockpiled in storehouses on the hill. The 55-hectare central area where these storehouses, watchtowers, and the garrison were located was heavily fortified, accessible only through gates in three narrow valleys. The foundations of 72 structures have been discovered at the site, which extends across a total of 120 hectares.
The dreaded Tang-Silla invasion never came, and Kikuchi Castle was gradually converted into a peacetime storage facility, remaining in use until the mid-tenth century. The fortress site is now a park with reconstructed buildings, including a grain warehouse, a barracks, and an octagonal drum tower. A lookout point provides an overview of the grounds, and visitors can learn more about the fort’s history at the Onkosouseikan Museum.