Wednesday, October 21, 2020

Ichinoseki Castle -Barrier, bridgehead or bridge point-

Ichinoseki Castle

-Barrier, bridgehead or bridge point-



Name: Ichinoseki Castle (Ichinoseki-jo)
Alias: Tsuriyama-jo (Tsuriyama castle)
Place: Tsuriyama Ichinoseki city, Iwate
Location: 38.924792516844654, 141.12851432805041
Type: Mountain Castle
Built: 16th century?
Remaining remnants: Clay walls and dry moats 

Brief History

Ichinoseki castle (一関城) is located over Tsuriyama-hill, one of about 70 meter height from hillside at the southwest of current Ichinoseki city central. Ichinoseki city stands at the south edge of Kitakami basin and Iwate prefecture, and at the middle of Sendai city and Morioka city and also at the middle of whole part of Tohoku region.

Kitakami-gawa river which runs straightly from the north part of current Iwate prefecture turns eastward before the hill area at the border of Miyagi prefecture and Iwate prefecture, then runs through the narrow valley toward south and heads to Ishinomaki area. Ichinoseki area is a meeting point of Kitakami-gawa river and Iwai-gawa river which runs westward to the curving point of Kitakami-gawa river.

As the hills at the border is not so high, Oshu Kaido road which connected Sendai area and Morioka area directly passed the hills from Ishinomaki area and arrives at Ichinoseki area just at the north of the hill. Even today major roads and railways passes Ichinoseki city and connect with east and westward traffic.

Usage as barrier and bridgehead

Because of its geographical condition at the south edge of Kitakami basin, castle site both worked as the barrier of Kitakami basin toward south and bridgehead of external power toward basin. It is said that this place is at first used as the camp of Tamuramaro Sakanoue (758-811), an excellent general of the Imperial Household who conquered Kitakami basin from the end of 8th century to the beginning of 9th century.

250 years after that, Abe clan which became a semi-independent power of Kitakami basin, and Abe clan built a fort at Tsuriyama hill then placed their relative Ieto Abe (?-?) as the commander of the fort. At 2 kilometer west there might be Komatsu-saku fort which was the large base of Abe clan, and Tsuriyama hill might be use as a watching place attached to Komatsu-saku fort.

In 1062, Yoriyoshi Minamoto (988-1075) who was the military noble of the Imperial Household and ancestor of Minamoto clan attacked Abe clan in the battle of Zen-Kunen. At this battle Yoriyoshi Minamoto might capture Tsuriyama hill and used as a bridgehead toward Abe clan.

20 year s after that Yoshiie Minamoto (1039-1106), son of Yoriyoshi Minamoto, intervened to the internal conflict of Kiyohara clan that seized Kitakami basin after the fall of Abe clan. At this time Yoshiie Minamoto also captured Tsuriyama hill and used as a bridgehead toward Kiyohara clan.

Hold by Kasai clan and Onodera clan

Oshu Fujiwara clan which established hegemony at Kitakami basin after the fall of Kiyohara clan placed their main base at Hiraizumi area just at the north of Ichinoseki area then they might use Tsuriyama-hill as their final defense line but there is no such record. After the fall of Oshu Fujiwara clan in 1189, Kamakura Shogunate placed their retainer Kasai clan as the lord of north part of Miyagi prefecture and south edge of Iwate prefecture including Ichinoseki area.

Kasai clan mainly resided at Ishinomaki area at the mouth of Kitakami-gawa river. Surrounding its main territories, Kasai clan placed their relatives and retainers from inland area to coast area throughout their territory. As the territory of Kasai clan spread toward current Mizusawa area and Iwayado area, Ichinoseki area was an important bridge point of territory and was governed by Okita clan or Takasaki clan.

In the former half of 16th century, Kasai clan moved their main base from Ishinomaki area to Teraike castle of Tome area. This might be done to strengthen the control of retainers which became independent from Kasai clan, and to compete with Osaki clan which was the lord at inland area next to the territory of Kasai clan.

As the Tome area was governed by important retainer Onodera clan, Kasai clan moved Onodera clan to Ichinoseki area. As a base of important retainer of Kasai clan, Ichinoseki castle might be improved into large medieval castle at this point. Onodera clan participated in the battle between Kasai clan and Osaki clan as the general of Kasai clan.

Structure of Ichinoseki castle

The shape of Tsuriyama hill is like a scissor f crab consists of two lines of ridges. Central area of the castle is a rectangular shaped one of about 80 meter long and 40 meter wide has a small basement at its west side and gate area at its northeast corner. At the south of central area, there are several terraces protected the backside of the castle.

At the north of central area, there is a secondary area now used as a garden and from that narrow terraces spreads along with two ridge lines. Between two ridges there are five terraces toward the hillside, but these terraces are too much clearly shaped and easy to climb thus they might be added at the time of construction of Tsuriyama park.

East line of the castle is protected by layers of narrow corridor areas on that the remnants of fences are found. West line of the castle is a sheer cliff faces the river and no need to protect, but east line needed protection and well kept the shape of the period of Onodera clan. Total size of the castle is about 400 meter long and 200 meter wide and suitable as a main base of Onodera clan.

End of Onodera clan

In 16th century, the main family of Kasai clan significantly lost its power among the conflict with strong retainers and subordinated to Date clan. In 1590, Kasai clan did not visit the headquarter of central ruler Hideyoshi Toyotomi (1537-1598) at Odawara campaign, and the territory of Kasai clan was confiscated along with Osaki clan. Kasai army resisted against the expedition army of Toyotomi government but was broken.

But after the return of Toyotomi army, former retainers of Kasai clan and Osaki clan including Onodera clan rebelled against Toyotomi government, under the support of Date clan. Next year Hideyoshi sent a large army to Tohoku region again to suppress rebels by ruined local lords throughout the region.

After the cease of the rebel, Masamune Date (1567-1636), the leader of Date clan, gathered survived generals of rebelled army and killed to erase the involvement of Date clan for the rebel. Dosho Onodewa (?-1591), the leader of Onodera clan, was killed at this time then the history of Onodera clan had ended.

Branch fort of Sendai domain and afterward

Territories of former Kasai clan and Osaki clan were given to Masamune Date, along with the confiscation of original territories such as Date area of Yonezawa basin. Ichinoseki castle was at first given to Masakage Rusu (1549-1607), the uncle of Masanume Date, and next Munekatsu Date (1621-1679), the 10th son of Masamune Date held Ichinoseki castle as the lord of branch domain of Sendai domain.

But in 1671 Munekatsu Date was expelled being blame for “Date Sodo”, an internal conflict of Sendai domain, then Ichinoseki castle was directly managed by Sendai domain again. Finally in 1682, Tamura clan which was the descendant of the lord of Miharu castle (Fukushima prefecture) and the house of Lady Mego (1568-1653), the formal wife of Masamune Date, was appointed as the lord of Ichinoseki domain.

Ichinoseki domain was the largest branch domain of Date clan, but Ichinoseki castle was not approved as a castle from Edo Shogunate thus was treated as a fort. Usage of mountain castle was prohibited, then Tamura clan built their residence at the east side of the hill now used as a ground of court. Tamura domain managed Ichinoseki area by the end of Edo era.

Today no building remains but structure of the castle roughly remain over the mountain, in spite of destructions at park construction. From the top of the castle hill, the scenery of south edge of Kitakami basin including traffic into Kitakami basin is clearly seen. Not so much recorded in the history, but this scenery certifies Ichinoseki castle had worked as barrier, bridgehead-and bridge point at Ichinoseki area.


20 minutes drive from Tohoku Jidoshado Expressway Ichinoseki interchange to parking of Tsuriyama Park. 

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Pictures (click to enlarge)

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