Genko borui (Genko [Mongol invasion attempts against Japan]) (borui [fort to prevent enemys attack]) (元寇防塁)
Genko borui is the fort constructed with stone along the coast area of Hakata Bay in Kitakyushu in the Kamakura period. It was constructed to prepare for Mongol invasion attempts against Japan (Genko). It was designated as a national historical site in 1933.
Genko borui' was named by Heijiro NAKAYAMA, but its original name is stone tsuiji (a mud wall with a roof).
Plan
In 1274, Yuan (Dynasty) (a dynasty nation at that time, which corresponds to present Mongol) conducted the first expedition (Bunei War) to Japan which had refused its repeated requests for commerce. Although Japan avoided Yuan's expedition by its retreat, it is said Japan could only manage defense in the battle. The Kamakura bakufu (Japanese feudal government headed by a shogun), which took hard-line measures in the negotiation after the war, such as killing of the envoys, started full-fledged guard against foreign countries. In the following year, 1276, the bakufu planned the dispatch of troops to Goryeo, and at the same time constructed stone tuiji.
Construction
The construction zone was designated in each province. According to the Stone Tsuiji Fueki (slave labor) Document of Osumi Province, stone tuiji labor was imposed at the rate of 1 sun (old unit of length,) per tan (old unit of land) of rice field, whether it belonged to the territory of samurai families or honjo ichienchi (over the territory of the Imperial court). Part of stone tsuiji was completed by the second expedition (Koan War) in 1281. It is said giving up landing in Hakata, the Yuan force berthed its fleet in Shikanoshima Island. The guard system against foreign countries lasted after the discontinuation of Yuan expedition to Japan, and the construction work and repair of damaged parts were imposed. The construction continued until 1332, one year before the fall of the Kamakura bakufu. Stone tsuiji at the time of construction is depicted in "Moko Shurai Ekotoba" (picture scrolls of Mongol invasion attempts against Japan) which Suenaga TAKEZAKI, a shogunal retainer in Kyushu, ordered to paint.
Structure
The height and width was two meter on average. It is generally believed the total length was about 20 km from Imazu, Nishi Ward, Fukuoka City in the west to Kashii, Higashi Ward, Fukuoka City in the east. With the inside filled with pebbles, the land side was built on slant, while the sea side upright. Shields were lined up, flags were placed on the tuiji, and piles were fixed at river mouths and shorefronts.
Borui Existing in Nagasaki Prefecture
The borui remains as it was in ancient times along 40 to 50 km of the coastline from Hoshika-cho, Matsuura City, Nagasaki Prefecture to Tabira-cho, Hirado City. There are a number of remains related with Genko in this area, which has not been much industrialized, as well as place names, such as '火立場,' '血田,' and 'Oidashi,' and old legends which are believed to be associated with it. They should be investigated in detail.
After Genko
Genko borui was constructed along the coastline from Imazu to Kashii, but when Fukuoka-jo Castle was built in the Edo period, most of borui was lost, because it was used as stones for the stone wall. The existing borui is the parts that miraculously survived, without being affected by it.
Existing Genko Borui
Presently, the borui has been weathered, and much of it has been buried in the ground, because the coastline has extended more offshore than in the Kamakura period due to land filling, etc. However, the borui in Imazu area (Nishi Ward, Fukuoka City), Iki-no-matsubara (Nishi Ward), Nishijin (Momochi) Area (Sawara Ward), Jigyo Area (Chuo Ward, Fukuoka City), and others has been maintained as a national historical site, and is kept exposed.