Sunday, May 13, 2018

Obata Castle -Castle like artificial dungeon-

Obata Castle

-Castle like artificial dungeon-



Name: Obata castle (Obata-jo)
Place: Obata Higashi-Ibaraki town, Ibaraki
Location: 36.266835964879725, 140.40214970852418
Type: Hill Castle
Built: 15th century
Remaining remnants: Clay walls and dry moats 

Brief History

Obata castle is located at a small height of about 10 meter height formed by Kansei-gawa river, a tributary of Hinuma-gawa river in the middle part of Ibaraki prefecture. Kansei-gawa river merges with Hinuma-gawa river at the east of the castle and flows into Hinuma march, the one of about 5 meter long known for its diversified ecosystem.

Middle part of current Ibaraki prefecture consist of several plateaus separated by rivers and marshes. Obata castle stands at the north edge of the height prolongs from Ishioka city toward east, being separated from Mito area at northward by Hinuma-gawa river and Tsuchiura area at southward by Koise-gawa river.

Local powers of Hitachi province

Hitachi province (Ibaraki prefecture) of Sengoku era is often grasped as the territory of Satake clan, but Satake clan seized the whole part of Hitachi province only at the final 10 year of the era. Satake clan was the governor of the province and leader of local lords but the province was separately held by local lords stayed at each plateau.

In the middle of 15th century, Satake clan only held the northernmost area of the province including current Hitachi Ota city and Naka area. Current Mito area including Mito castle was held by Edo clan, insisted as an descendant of ancient military noble Hidesato Fujiwara (?-?) and held their territory around current Naka-gawa river. 

Edo clan once lost its power during the conflict between the North Court and the South Court in 14th century, but barely survived people recovered their power in 15th century. On the other hand, current Ishioka area was reigned by Daijo clan, another traditional clan stem from Taira clan once spread in Hitachi province in 10th century.

Obata castle between Daijo clan and Edo clan

Ishioka area had been the center of Hitachi province from ancient era to medieval era, being centered at the middle of Tsuchiura area and Mito area and had a good access of marine transportation from Lake Kasumigaura. Province office was built at Ishioka area, and Daijo clan had a high authority as an assistant of province office.

Formerly Daijo clan had both of current Ishioka area and Mito area. But being involved in the revolt of Zenshu Uesugi (?-1417) against Kamakura Kubo highness, Daijo clan lost Mito castle and fell into a small local lord of Ishioka area, then had to face the pressure of Edo clan which seized Mito area instead of Daijo clan.

It is said that Obata castle was built by Daijo clan in around 1420, probably a connecting point of Ishioka area and Mito area. The sight of castle is also an entrance into a long plateau continues to Namekata area and Kashima area, and it might be built to manage the local communication.

However, as Daijo clan lost Mito area, Obata castle became the front fort of Daijo clan against Edo clan. In spite of resistance, Daijo clan also lost Obata castle by the end of 15th century, and Obata castle turned to the bridgehead of Edo clan against Daijo clan. In the middle of 16th century, Edo clan significantly reformed Obata castle as a front fort to attack Fuchu castle, the main base of Daijo clan at Ishioka city.

Structure of Obata castle

Obata castle is built on the edge of peninsular like plateau spread toward east, being surrounded by deep marsh. Expected front line of the castle is the western line where current Higashi-Kanto Jidoshado Expressway runs, but the plan of castle expects the attack from four direction.

Central area of the castle is a square shaped area of 100 meter long, which is encircled by tall clay wall and deep dry moat with its front gate at the middle of southern line. Encircling this central area, large five areas all exceeds 100 meter long and also protected by the line of deep dry moat are built, with the basement of turret built at critical area.

The characteristic feature of Obata castle is its dry moats not only deep and wide but also complexly folded like a maze. The depth of these moat exceeds 10 meter, piling up the sands achieved by digging dry moat into the clay wall. The enemy soldier had to proceed the bottom of this deep moat to approach to central area, and were exposed by attack of guardians from upside.

Dry moats of the castle had several diverging point like a dungeon, to separate the enemy and got lost. If the intruder chose wrong way, they might exit the castle without any achievement. Even now visitors can get lost without detailed map, and under the confusion of the battle it could easily occur.

Rise of Satake clan

In the latter half of 16th century, Satake clan significantly grew their power then both of Daijo clan and Edo clan had to subordinate to Satake clan. Edo clan was supreme to Daijo clan, but considering the relationship with Satake clan, Edo clan could not ruin Daijo clan by the end.

In addition to this, Satake clan itself had to face with Hojo clan, the large warlord of Sagami province (Kanagawa prefecture) which aimed the unification of Kanto region. Under Satake clan, Edo clan and Daijo clan fought against Hojo clan or Oda clan of Oda castle subordinated to Hojo clan at different place.

In 1590, this subtle situation became a sudden end. Hojo clan was ruined by central ruler Hideyoshi Toyotomi (1537-1598), and Satake clan which cooperated with Hideyoshi and participated in the campaign was approved as the governor of whole part of Hitachi province. On the other hand, both of Edo clan and Daijo clan could not accompany with Satake clan to restrain the other.

Fall of two clans and afterward

Utilizing this as an opportunity, Satake clan ruined remaining local powers including both of Edo clan and Daijo clan then captured whole part of Hitachi province. Under Satake clan Obata castle was used as a local fort and managed by its retainer of Wada clan, but along with the transfer of Satake clan after the battle of Sekigahara in 1600 Obata castle was finally abolished.

Today no building was lost but the structure of the castle nearly completely remain in the wood, except for outer barrier disappeared by the construction of highway. There are many castles in Hitachi province that have excellent clay walls and dry moats built by both of Satake clan and Hojo clan, but the completeness of Obata castle is ahead of other castles. 

Minowa castle (Gunma prefecture), Kozukue castle (Kanagawa prefecture) or Masuyama castle (Toyama prefecture) are regarded as castles having powerful and well remaining dry moats, and Obata castle is equivalent to these castles. Being located at a bit inconvenient area only arrived by car but it is worth for visiting.


15 minutes drive from Joban Jidoshado Expressway Iwama interchange.

Related Castles


Pictures (click to enlarge)

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