Sunday, June 17, 2018

Ohara Castle -Castle at valley of gold sand and iron sand-

Ohara Castle

-Castle at valley of gold sand and iron sand-



Name: Ohara castle (Ohara-jo)
Alias: Yamabuki-jo (Yamabuki-castle)
Place: Ohara Daito-cho Ichinoseki city, Iwate
Location: 39.01939480517768, 141.39409101821394
Type: Hill Castle
Built: 14th century
Remaining remnants: Clay walls and dry moats 

Brief History

Ohara castle (大原城) spreads over a hill of about 50 meter height from hillside, which spreads from Hayama-yama mountain at the north of former Daito town. Daito area is a small basin of about 10 kilometer long and 5 kilometer wide between Kitakami-gawa river and Kitakami Mountains, at the midst of current Ichinoseki city and Rikuzen Takata city.

Daito area is a basin formed by Satetsu-gawa river, a tributary of Kitakami-gawa river which was a name of “iron sand” river. As this river erodes Kitakami mountains, which was formed by the activity of volcano of deep sea and emerged to the terrain by land rise, plenty of iron sand and gold sand were found along this river. 

Origin of Ohara clan and Ohara castle

Before the arrival of mining technology, iron and gold were acquired only by the sand, and iron sands around this area supported the prosperity of Oshu Fujiwara clan, which had main base at Hiraizumi area at 20 kilometer west from castle site and once dominated north half of Tohoku region in 12th century. Fujiwara clan also grew casting of iron items utilizing iron sand of this area, later turned to famous Nanbu iron products.

Precise year is unknown but Ohara castle was built by local lord Ohara clan in 14th century. Ohara clan was a descendant of Chiba clan, a strong samurai group originally spread around current Chiba city. Chiba clan served as a commander at the battle of Kamakura Shogunate against Oshu Fujiwara clan, and acquired former territory of Oshu Fujiwara clan as a reward.

At this time Kasai clan, which was originally the lord of Kasai castle at current Kasai area of Tokyo metropolis, seized Hiraizumi area which was the main base of Fujiwara clan then became the supervisor of Tohoku region. Chiba clan acquired Pacific Ocean side areas, and placed their branch families at each area. Ohara clan was one of such descendants of Chiba clan.

Largest retainer of Kasai clan

After the fall of Kamakura Shogunate, Kasai clan lost its power among the conflict between the South Court and Muromachi Shogunate at Tohoku region, and Muromachi Shogunate sent their relative Osaki clan and Mogami clan as the supervisor of the region. Furthermore, at the middle part of Tohoku region, Date clan gradually grew the strong warlord, and Kasai clan lost its position as the supervisor of region.

However, Kasai clan proceeded into the east half of Osaki plain along with Kitakami-gawa river, including sea ports such as Kesennuma area or Ishinomaki area. Utilizing the river transportation of Kitakami-gawa river and Marine transportation of Sanriku area, Kasai clan grew their power as a major lord of the area…

Under Kasai clan, Ohara clan also grew to the largest retainer of Kasai clan. In addition to minerals produced in the territory, it was an important connection of Osaki plain where Teraike castle, the main base of Kasai clan exists, Kitakami basin and coastal area of Sanriku coast. Ohara castle might be expanded along with the grow of Ohara clan.

Structure of Ohara castle

Ohara castle is built over a slightly curved ridge of the hill toward east and west. Central area of the castle is a roughly oblong shaped one of about 100 meter long and 30 meter wide, which has a basement of main building at its eastern line. The western line is well shaped into sheer wall, and there might also be a turret.

Secondary area is a square shaped one of about 80 meter at the east of central area, ahead of dry moat. Ahead of secondary area, a small area and dry moat protected the eastern edge of the castle, and backside gate is built with small buffer area.

On the opposite, third area covers the western edge of the castle, along with another terrace ahead of dry moat. Southern slope of the hill faces castle town is separated into numerous terraces, to prepare camping site of soldiers and prevent the climbing of enemies. Total size of the castle is about 500 meter long and 300 meter wide, and its size and remnants well shows the power of Ohara clan.

Struggle against difficulty of master

Since the latter half of 15th century, Kasai clan started to decline because of internal and external problems. Kasai clan became hostile with Osaki clan which held the western half of Osaki basin, and allied with Date clan to compete with Osaki clan which was supported by its relative Mogami clan.

But alliance with stronger Date clan brought intervention from Date clan, and along with occurring internal conflict of Date clan divided Kasai clan. Retainers at distant Sanriku area such as Hamada clan and Kumagai clan left the control of weakened Kasai clan, and Nanbu clan which had the north half of Kitakami basin started to advance southward.

Among such situation, Ohara clan consistently supported Kasai clan as a pillar of northward. Ohara clan crushed internal conflict of Kumagai clan at Kesennuma area, also ruined Hamada clan revolted against Kasai clan at Rikuzen Takata area. As a highest retainer, Ohara clan desperately supported declining Kasai clan.

Sudden end of Ohara clan and afterward

However, in 1590, Kasai clan did not visit the siege of central ruler Hideyoshi Toyotomi (1537-1598) toward Hojo clan, because of consideration to Date clan and fear of revolt. But because of this absence Kasai clan was confiscated its territory, and Ohara clan also lost their land. Next year Ohara clan participated in the revolt of former retainers of Kasai clan and Osaki clan against Hideyoshi, and their family was extinguished at this battle.

After the crush of this rebellion, Toyotomi government abolished many castles at this area but decided to remain Ohara castle as a regional base. Mitsunari Ishida (1560-1600), later chief administrative staff of Toyotomi government, reformed Ohara castle into modern castle having main tower and Masugata style combined gate, then left it to Date clan moved to former territory of Kasai clan and Osaki clan.

Date clan used Ohara castle as a branch castle, but it was abolished under Ikkoku Ichijo Rei (one castle and one domain rule). But the importance of Ohara area did not change thus an administrative office of Date clan was built at hillside of the castle, where might be former residence of the lord. Even now at the both side of Satetsu-gawa river there is an administrative area and commercial area, both stem from past castle town.

Now all building was lost but structure of the castle well remain on the hill. As the castle slightly curves, central area seen from the south edge of secondary area has a powerful exterior curving up to the peak. Even though not so well known, but its structure and purpose is clear and worth to visit along with neighbor sightseeing spots such as Hiraizumi ruins or Geibikei valley. 


40 minutes drive from Tohoku Jidoshado Expressway Ichinoseki interchange.

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Pictures (click to enlarge)

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