Saturday, October 17, 2020

Iwayado Castle -Castle reflects long term history of Esashi area-

Iwayado Castle

-Castle reflects long term history of Esashi area-



Name: Iwayado Castle (Iwayado-jo)
Place: Esashi-Iwayado-Tateshita, Oshu city, Iwate
Location: 39.198257139923626, 141.1804727681007
Type: Mountain Castle
Built: 14th century?
Remaining remnants: Gate (moved), clay walls and dry moats 

Brief History

Iwayado castle (岩谷堂城) is located at Tateyama hill, one of about 70 meter height from hillside at the northeast of Iwayado town. Castle site is at the end of the hill spreads westward from Kitakami-Kochi height toward Kitakami-gawa river. The southward of the hill is vertically cliff eroded by Hitokabe-gawa river like an artificial canal, it is a suitable place to control the watershed of Hitokabe-gawa river and protect itself.

Kitakami basin which forms major part of current Iwate prefecture consists of Kitakami-gawa river, the main stream flows southward like a backbone and tributaries flows horizontally to Kitakami-gawa river like ribs. Important place of this area has been placed at the merging point of Kitakami-gawa river and tributaries, including current capital Morioka city.

Entrance of cetnral Dynasty into Esashi area

Iwayado area itself is a meeting point of Hitokabe-gawa river and Kitakami-gawa river, and also close to the meeting point of Izawa-gawa river and Kitakami-gawa river. Izawa-gawa river is a route toward Yokote basin across Oshu Sanmyaku mountains, and Hitokabe-gawa river was also a route toward Tono area or Rikuzen-Takada area.

As the traffic of Kitakami basin was strongly affected by rivers, Esashi area which Iwayado area belongs had been most important area in Kitakami basin during ancient era. In 802, Tamuramaro Sakanoue (758-811), a great general of the Imperial Household, built Izawa castle which was the first large size castle at Kitakami basin at 3 kilometer west of Iwayado area opposite of Kitakami-gawa river.

Isawa castle had been the center of administration and military of central government at Kitakami basin throughout 9th century. Before the arrival of Tamuramaro Sakanoue, Aterui (?-802) who was the leader of local resident resided at Izawa area fought with the Imperial Household army and once broke it at the battle of Subushi, but was broken by Tamuramaro Sakanoue.

Period of Abe clan and Kiyohara clan

In 10th century, Abe clan which might be also the leader of local residents grew their power and managed whole part of Kitakami basin from its main base Toyominosaki fort, also at 3 kilometer west from Iwayado area but at the north of Isawa-gawa river opposite of Isawa castle.

Abe clan became semi-independent power from central government and once broke the Imperial Household army at the battle of Onikiribe in 1051, but was attacked by an alliance of Yoriyoshi Minamoto (988-1075) who was the leader of Minamoto clan and Kiyohara clan that was the lord of Yokote basin then was ruined in the battle of Zen-Kunen (former nine years).

Instead of ruined Abe clan, Kiyohara clan grew its power at Yokote basin and succeeded the former territory of Abe clan. But as a result of internal conflict for successor, Kiyohira Fujiwara (1056-1128), who was the son of Tsunekiyo Fujiwara (?-1062) that accompanied with Abe clan and was killed after the battle of Zen-Kunen.

Period of Oshu Fujiwara clan

Survived Kiyohira Fujiwara was adopted by Kiyohara clan and became one of the successors, but a conflict aroused against real son of Kiyohara clan then asked support to Yoshie Minamoto (1039-1106). Yoshiie and Kiyohira ruined Kiyohara clan at the battle of Go-Sannen (later three years), then Kiyohira Fujiwara became the lord of Kitakami basin.

Kiyohira Fujiwara placed its main base at Toyodanotachi fort, about 1 kilometer south of Iwayado castle, where was originally the residence of Tsunekiyo Fujiwara. It is said that Iwayado castle was the residence of Kiyohira Fujiwara but considering other castles of Abe clan or Kiyohara clan built at river terrace, Iwayado castle might not be the residence but there could be an evacuation or watching fort at this place.

In 1099, Kiyohira Fujiwara moved its main place from Toyodanotachi fort to Hiraizumi area at the south edge of Kitakami basin, but Toyodanotachi fort was kept as one of the major five fort of Oshu Fujiwara clan. After one century in 1189, Oshu Fujiwara clan was ruined by Yoritomo Minamoto (1147-1199), the founder of Kamakura Shogunate and a formal descendant of Yoshiie Minamoto who helped the rise of the clan.

Origin of Kasai clan and Esashi clan

After the fall of Oshu Fujiwara clan, Yoritomo Minamoto gave the north edge of current Miyagi prefecture and south edge of Iwate prefecture to Kasai clan, which was originally a local lord of Kasai area at Tokyo metropolis. Kasai clan was also appointed as the general commander of Mutsu province and governor of Hiraizumi area.

As Iwayado area was close to the border between Kasai clan and Waga clan, Kasai clan placed their relative to Esashi area to protect north edge of the territory, and they renamed as Esashi clan. At first Esashi clan resided at the next of the border, but later moved to Iwayado area where was suitable to manage whole part of Esashi providence.

Esashi clan might build Iwayado castle utilizing remnant of the fort of Oshu Fujiwara clan. Same as other clans, Esashi clan placed their relatives and retainers throughout Esashi area, such as Hitokabe clan of Hitokabe castle (Iwate prefecture) at the upstream of Hitokabe-gawa river, or Oikawa clan at Nodesaki castle (Iwate prefecture).

Turbulent history of Esashi clan

After the fall of Kamakura Shogunate in 1333, Tohoku region was involved into the conflict between Muromachi Shogunate and the South Court. Among the conflict Kasai clan separated and struggled each other then declined. Furthermore, Muromachi Shogunate which broke the South Court sent their relative Shiba clan as the general governor of Kitakami basin then Kasai clan had to compete with it.

Among such situation, Esashi clan served as the guard of north border of Kasai clan, along with Kasuyama clan at the west of Kitakami-gawa river. In the end of 15th century Esashi clan rebelled against the main family of Kasai clan but was broken, then Kasai clan against sent their relative as the leader of Esashi clan. 

Since the beginning of 16th century, Nanbu clan which was originally the lord at the border of current Iwate prefecture and Aomori prefecture expanded their territory toward south, to the south edge of Iwate prefecture. Without reinforcement army from Kasai clan, Esashi clan barely protected themselves from Nanbu clan. Reflecting severe situation Iwayado castle might be expanded at this time.

Structure of Iwayado castle

Central area of the castle is a roughly oblong shaped one of about 100 meter long and 30 50 meter wide, which has a clay wall at its north end and south end but formerly might be wholly surrounded by clan wall. The north half of the area currently used as a ground of shrine and hall might be used for main residence, and it has a main gate at the middle of western line.

Central area of the castle is surrounded by layer of corridors area and dry moats. Terraces spread toward southeast ahead of dry moat, toward the lowest terrace currently used as a parking. At the west of central area, two terraces are built separated by dry moat, and at the side of these areas there was a former main gate of the castle.

At the west of these two areas, there is a huge secondary area that is about 150 meter long square formerly used as a ball field. Originally it has a masugata-style buffer area of main gate at the middle of south line but it disappeared by construction of the ground. But clay wall, and water moat of main gate still exist with slightly remained remnant of stone wall.
Total size of the castle is about 400 meter long and 200 meter wide, and relatively large one at the area. Considering the shape of the hill, formerly the outer line might be built at the whole part of the hill at the south of saddle point, including residences of the retainers spread at the south of castle area to the south edge of the hill.

Fall of Esashi clan and rebel against central authority

In 1590, Kasai clan was expelled by not visiting the headquarter of central ruler Hideyoshi Toyotomi (1537-1598) at Odawara campaign. Esashi clan was also expelled along with its master Kasai clan, then Esashi clan became the retainer of Nanbu clan and survived.

Hideyoshi Toyotomi appointed his retainer Yoshikiyo Kimura (?-1598) as the lord of former territories of Osaki clan and Kasai clan. Yoshikiyo Kimura placed his retainer Geki Mizoguchi (?-1590) as the commander of Iwayado castle. But due to opposition to the policy of Hideyoshi and Yoshikiyo, former retainers of Osaki clan and Kasai clan rebelled against Kimura clan after the return of the army of Hideyoshi. 

Rebel army broke the army of Yoshikiyo Kimura around the territory and Geki Mizoguchi died in the battle. Next year in 1591 the rebel was suppressed by second time expedition of Toyotomi army, and Masamune Date (1567-1636) was appointed as the lord of former Osaki and Kasai territory. 

Iwayado fort under Sendai domain and afterward

Masamune Date placed his important retainer Masanaga Kori (1561-1593) as the commander of Iwayado castle, but Masanaga soon died in ill. After that Iwayado castle was directly managed by Date clan and the commanders of the castle changed in short term. Under Ikkoku Ichijo Rei (one domain one castle rule), Iwayado castle was not a formal castle but continued as local fort of Sendai domain.

As a fort, central area of the castle was disposed then secondary area was used as the center of the castle. In 1659, Munenori Date (1643-1685) who was the relative of Date clan was appointed as the lord of Iwayado fort, and continued by the end of Edo era. Finally Iwayado fort was abolished at the time of Meiji Revolution.

Today no building except for transferred one gate remains but structures of the castle well remain on the hill except for broken main gate at secondary area. Curved clay wall and dry moat are the structure of medieval era, and remnant of stone wall was the feature of early modern period. 

At the opposite of Hitokabe-gawa river, there is a theme park of the period of Oshu Fujiwara clan originally built as a location set of TV drama. The scenery of Tateyama hill reflects the long history of Esashi area and Kitakami basin, from the prosperous ancient era to turbulent medieval era and steadily developed early-modern period.


20 minutes drive from Tohoku Jidoshado Expressway Mizusawa interchange to parking of Tateyama Historical Park. 

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Pictures (click to enlarge)

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