Friday, October 14, 2016

Iwakiri Castle -Bitter experience-

Iwakiri Castle

-Bitter experience-



Name: Iwakiri castle (Iwakiri-jo)
Alias: Takamori-jo (Takamori-castle)
Place: Iwakiri-iriyama Miyagino-ku Sendai city, Miyagi
Location: 38.31367633874967, 140.94044397485746
Type: Mountain Castle
Built: 13th century?
Remaining remnants: Clay walls and moats 

Brief History

Iwakiri castle (岩切城) is built around the peak of Takamoriyama mountain, one of about 100 meter height from hillside at the north edge of current Sendai city. Castle site is at the south edge of Matsushima height which runs east and west ward then separates Sendai plain into south half and north half, and also at the corner of cliff which is formed by Nanakita-gawa river and Sunaoshi-gawa river.

Today castle site is deep inside of flat land, but in medieval era coast line was much insider than now thus castle site was at the next of narrow lowland. As Sendai plain was the northernmost good and safe port with flat land and entrance into the north half of Tohoku region along with Kitakami-gawa river, Yamato dynasty built Tagajo castle at the hill next to Takamoriyama mountain as a vice capital at Tohoku region. 

Because of this, Oshu Kaido road which connected central area and Tohoku region ran between Tagajo castle and Takamoriyama mountain, and because of it location and shape of the mountain protected by sheer cliffs, Iwakiri castle had been an important point to control the communication at Sendai plain and protect Tagajo castle.

Origin of Iwakiri castle and Rusu clan

In the north and middle part of current Miyagi prefecture, unlike south part and other provinces at Tohoku region, there was almost no large medieval mountain castle except for Iwadeyama castle or Sendai castle built at later period. Terrain of these areas are mainly flat land or height, and the situation had been relatively stable under Osaki clan and Kasai clan throughout Muromachi era, in spite of decline of both clans. But Iwakiri castle was an exceptionally large mountain castle at this area.

Iwakiri castle was built by Rusu clan around the beginning of 13th century. Rusu clan was said as a descendant of central noble Fujiwara clan, and originally named as Izawa clan. In the latter half of 12th century, Iekage Izawa (?-1221) became the retainer of Yoritomo Minamoto (1147-1199). the founder of Kamakura Shogunate.

As a descendant of central noble, Izawa clan had a skill in documentation and administration, then Yoritomo Minamoto who established Kamakura Shogunate thought important of the talent of Iekage Izawa for administration. After the extinction of Oshu Fujiwara clan which dominated north half of Tohoku region as a half independent power over 100 years, Yoritomo appointed Iekage as a position of Rusu-shoku which was a chief administrative staff of Tagajo castle.

High class administrative staff of Tohoku region

Based on this position, Izawa clan had a command to other neighbor retainers of Kamakura Shogunate then had a high position at this area. Later Izawa clan changed their surname to Rusu clan based on their position, and also built Iwakiri castle at the next of Tagajo castle as their main base. 

Rusu clan kept their power throughout Kamakura era, but after the fall of Kamakura Shogunate in 1333, they were involved in disturbance. Emperor Godaigo (1288-1339) who beat Kamakura Shogunate in cooperation with Takauji Ashikaga (1305-1358) sent Prince Norinaga (1328-1368, later Emperor Gomurakami) and his brilliant general Akiie Kitabatake (1318-1338) to Tagajo castle to reign Tohoku region.

At first Rusu clan belonged to Akiie and was appointed as an administrative staff. When Takauji left Emperor Godaigo and established his own Muromachi Shogunate, Akiie made a long expedition toward Kyoto city to beat Takauji and once expelled Takauji from Kyoto city. But after the return of Akiie, Takauji restored his power at Kyushu island then returned to Kyoto city defeating Emperor side generals. Emperor Godaigo left Kyoto city and opened South Court at Yoshino area.

Bitter experience

Looking at this situation, Rusu clan turned to Takauji Ashikaga and became the retainer of Muromachi Shogunate. Shogunate sent Takakuni Hatakeyama (1305-1351) as the general lord of Tohoku region, but when internal conflict of Muromachi Shogunate between Takauji and his younger brother Tadayoshi Ashikaga (1306-1351) occurred, Takakuni who belonged to Takauji and his colleague Sadaie Kira (?-?) supported Tadayoshi became opponent.

Rusu clan belonged to Takakuni, but in 1351, Rusu clan was attacked along with Tadakuni Hatakeyama at Iwakiri castle by Kira Sadaie. Iwakiri castle fell by Sadaie, then leader of Rusu clan died in the battle and Rusu clan once declined. After the defeat of Tadayoshi Ashikaga Rusu clan revived, but had to subordinate to Osaki clan which was a relative of Muromachi Shogunate and appointed as the general governor of Tohoku region.

In 15th century, Osaki clan gradually lost their power along with their source of the power Muromachi Shogunate, and Date clan which was originally a traditional but small local lord at the north edge of current Fukushima prefecture gradually grew their power beating surrounding lords. 

South part of current Miyagi prefecture including Iwakiri castle became a disputed area of Osaki clan and Date clan, and Rusu clan itself had a conflict with Kokubu clan at current Sendai city area, since the former battle of Iwakiri castle. Under such circumstance, Rusu clan expanded and strengthened Iwakiri castle for survival.

Structure of Iwakiri castle

Iwakiri castle spreads over "m" letter shaped ridges of Takamoriyama mountain. Central area of the castle is a roughly oblong shaped area of 80 meter long and 20 meter wide, at the root of middle line. At the south of central area, there are several terraces such as secondary area and third area stand in line. Eash area is well shaped as flat and separated by height gap, and the lowest area is surrounded by clay wall.

At the western line which is connected with gentle slope to the hillside, there is a long and narrow straight line of many small terraces separated by dry moats and clay walls to prevent the intrusion of the enemy. At the tip of this straight line, there might be a guarding turret over the clay basement. Each edge of this line is also protected by dry moats, especially at the east side which faces core area of the castle.

On the other hand, eastern part of the castle is a wide and gentle space suitable to build a residence. At the center of eastern part, there is a large flat area of 80 meter long equips L shaped clay wall, which might be the ground of residence of the lord. There are numerous terraces built at three ridges spread from this central part, and each end was also protected by clay walls and dry moats. Total size of the castle reached to 600 meter long and 400 meter wide, and extraordinary a large one around this area.

Being suffered from internal conflict, Rusu clan continued its history based at Iwakiri castle. But pressure from Date clan became stronger and stronger, in 1500, Rusu clan adopted the people of Date clan as their leader then subordinated to Date clan. Since then Rusu clan became a major retainer of Date clan and expanded their power under Date clan.

Trusted relative of single-eyed dragon

In 1567, Masakage Rusu (1549-1607), son of Harumune Date (1519-1578) who was the leader of Date clan, was adopted by Rusu clan as a leader again. Muraoka clan which was an important retainer of Rusu clan opposed to this adoption and revolted in 1569, but Masakage suppressed this rebellion and united the clan. 

Masakage Rusu who surpassed this revolt changed his main base from Iwakiri castle to Rifu castle which was originally the main base of Muraoka clan. Iwakiri castle was surely a secure castle protected by cliffs, but structurally tend to be divided at the siege by enemy. Rifu castle spreads over single lined hill and was easy to control soldiers uniformly. Iwakiri castle was abolished at the time of this moving.

After the move to Rifu castle, Masakage Rusu activated at many battles supporting his elder brother Terumune Date (1544-1585) and his nephew Masamune Date (1567-1638) who was praised as a single-eyed dragon, and contributed to the expansion of Date clan. When Masamune Date subordinated to central ruler Hideyoshi Toyotomi (1537-1598), the territory of Rusu clan was confiscated but Rusu clan kept as an important retainer of Date clan.

Afterward of castle

At the time of the battle of Sekigahara in 1600, Masakage was sent as a reinforcement to Yoshiaki Mogami (1544-1614), who was an uncle of Masamune and attacked by Kagekatsu Uesugi (1556-1623). Masakage chased Uesugi army which head the result of the battle of Sekigahara and retreated, and gave damage to them. After the battle Masakage Rusu was appointed as the commander of Ichinoseki castle, then Rusu clan moved to the lord of Mizusawa castle and continued by the end of Edo era.

Now all building was lost but clay structures of the castle well remain over the mountain. Even though mainly consist of simple terraces, well shaped layers of terraces are magnificent by themselves different from neighbor castles. Iwakiri castle also is valuable by keeping medieval shape, as it was not used as a branch castle of Sendai remain unlike other large medieval castle at Miyagi prefecture. 

The size and security of the castle shows bitter experience of Rusu clan, once pushed Rusu clan to the corner of extinction but urged them to had a secure castle and supported to continue under tough situation. Today castle site become a part of Takamoriyama park, and covered by cherry blossoms in spring.


40 minutes walk from JR East Tohoku-Honsen line Iwakiri station. 15 minutes drive from Tohokudo Expressway Izumi interchange to Takamoriyama park.

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Pictures (click to enlarge)

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