Wednesday, August 5, 2020

Tsukuroumi Castle -History of peninsular brave (4) sea port of active Satomi navy-

Tsukuroumi Castle

-History of peninsular brave (4) sea port of active Satomi navy-

造海城, 百首城


Name: Tsukuroumi castle (Tsukuroumi-jo)
Alias: Hyakusyu-jo (One hundred poem castle)
Place: Takeoka Futtsu city, Chiba
Type: Mountain Castle
Built: Around 1500?
Remaining remnants: Stone walls, clay walls and moats 

Brief History

Continued from Part 3

Tsukuroumi castle spreads over Shiroyama mountain, one of about 100 meter height from hillside at the mouth of Byakko-gawa river in the south part of Futtsu city. Castle site faces Uraga-Suido straight, the one between Miura peninsula and Boso peninsula that length and width is about 15 kilometer and 10 kilometer, at the mouth of Tokyo bay.

Uraga Suido straight is a critical sea area where hundreds of large ships toward and from Tokyo and Yokohama port sails each day. Horizontal sail between two coast line significantly decreased due to the construction of undersea Tokyo-wan Aqua-line tunnel, but even now Tokyo-wan Ferry connects both side of the straight between Kanaya port and Kurihama port.

Coast people of Tokyo bay

Japanese medieval navy grew mainly at island area such as Setonaikai-Sea or Ise-Shima area or bay area such as Suruga-wan bay or Tokyo-bay, as they emerged from coast people who engaged in coastal marine transportation then armed for self-defense. At straight coast line there is no opponent to trade by small ships, then except for intentional growth by warlords there was no navy at such area.

Uraga Suido straight was ideal area for such medieval navy, even though having no island but closeness of two rich areas across narrow straight brought prosperity of coastal marine trade at this area. Even before the development of Edo city, there are many ports around Tokyo bay, and inner bay transportation was connected to outer marine transportation at the straight.

During 15th century, apart from the conflict of land power such as Kamakura Kubo or Kanto Kanrei at west coast of Tokyo bay, east coast of the bay was comparably apart from the conflict then coast people gathered and turned into local lords of their port such as Anzai clan or Masaki clan.

Rise and fall of Mariyatsu Takeda clan

In the latter half of 15th century, Koga Kubo Highness sent Mariyatsu Takeda clan and Satomi clan to Kazusa province (middle part of Boso peninsula) and Awa province (south edge of Boso peninsula) respectively, to cope with Uesugi clan which was at Kanto Kanrei position and held Miura peninsula including Kamakura city.

By the end of 15th century, Mariyatsu Takeda clan and Satomi clan seized Kazusa province and Awa province. As Tsukuroumi castle was at the south border of Kazusa province toward Awa province, Mariyatsu Takeda clan built the castle both for the seize of marine transportation at Takeoka port at the next of the castle and preparation toward Satomi clan at Awa province.

Mariyatsu Takeda clan had many castles such as Mariyatsu castle, Otaki castle, Kururi castle or Sanuki castle at Kazusa province and experienced peak period under its leader Jyokan Mariyatsu (?-1534). But Oyumi Kubo which was supported by Mariyatsu Takeda clan reversely suppressed Mariyatsu Takeda clan, and both of Oyumi Kubo and Mariyatsu Takeda clan suffered fatal damage at the defeat of the first battle of Konodai in 1538.

Fall of Tsukuroumi castle at internal conflict

Before the defeat of the battle, Mariyatsu clan fell into severe internal conflict between Nobutaka Mariyatsu (?-1551) who was close to Hojo clan and Nobumasa Mariyatsu (1515-1552) who was assisted by Satomi clan. Nobutaka Mariyatsu who resided Minegami castle which was close to Tsukuroumi castle placed his son Nobumasa Mariyatsu (?-1552) at Tsukuroumi castle.

Before the attack of Satomi clan, Nobutaka Mariyatsu opened Minegami castle and ran to Tsukuroumi castle. But Tsukuroumi castle was heavily surrounded by Yoshitaka Satomi (1507-1574) in 1537, thus Nobutaka Mariyatsu told Satomi army to open Tsukuroumi castle in exchange of 100 Japanese poems, and receiving so Nobutaka left Tsukuroumi castle then ran into Hojo clan.

After the battle of Konodai, Hojo clan which won the battle placed Nobutaka Mariyatsu at Shiizu castle (Chiba prefecture) at the north edge of Kazusa province. But Yoshitaka Satomi ruined both of Nobutaka Mariyatsu and Nobumasa Mariyatsu who left Satomi clan and agreed with Nobutaka Mariyatsu, then the history of Mariyatsu Takeda clan as an independent warlord had ended in 1552.

Masaki clan as commander of Satomi navy

Yoshitaka Satomi who seized south half of Kazusa province placed Masaki clan at Tsukuroumi castle and Kanaya castle, the front line toward Uraga straight. Masaki clan is said as a descendant of Miura clan prospered at Miura peninsula opposite of Uraga straight, and originally a local lord of Kamogawa area at east coast of Boso peninsula.

Masaki clan was a core of Satomi navy throughout 16th century. Originally Satomi clan landed to the south edge of Boso peninsula from sea and expanded its territory throughout Awa province, Satomi clan was close to local navy such as Anzai clan at west coast and Masaki clan at east coast.

In 1516, Soun Hojo (1456-1519) who entered Kanto region from Izu province (Izu peninsula) ruined Miura clan which prospered at Miura peninsula after three year siege. Miura clan had strong navy and navy base such as Misaki castle or Uraga castle (Kanagawa prefecture), and Miura navy was lost during the battle.

Active attack of Satomi navy

Looking at the disappearance of good counterpart, Satomi navy that felt antipathy against Hojo clan attacked the town of Hojo clan at Miura peninsula. Hojo clan ruined many local navy of Izu peninsula and Miura navy, and tried to construct Hojo navy gathering remaining Izu navy or Miura navy and called Kajiwara clan from Kumano navy but it took time.

Furthermore, in 1524, Hojo clan captured Edo castle (Tokyo metropolis) and Shinagawa port, the most important port of inner part of Tokyo bay. As weat coast of Tokyo bay was seized by Hojo clan, the interest of local navy at east coast of Tokyo bay might be seriously injured. From this situation Satomi clan became to hostile to Hojo clan even land territory was still apart.

In 1526, Satomi navy crossed Uraga straight in a body and raided Miura peninsula. Satomi army landed to Jogashima island at the side of Misaki port, then captured Misaki castle and Arai castle from the sea. Next Satomi army proceeded to Kamakura city and plundered at Kamakura city.

Failure of Satomi navy

But during this battle, Tsurugaoka Hachimangu Shrine which was the highest shrine among the samurais of Kanto area had burnt down. Frightened Satomi army turned to Tamanawa castle (Kanagawa prefecture) at neighbor place but was broken by counter attack of Hojo army then finally retreated from Miura peninsula.

The demolition of Tsurugaoka Hachimangu Shrine was a fatal mistake of Satomi clan, and increased the authority of Hojo clan promptly decided to rebuild it. Satomi army could not keep Kamakura city only saw it, and finally Yoshitoyo Satomi (?-1534) who was the leader of Satomi clan at this assault was ruined by the coup d’?tat by Yoshitaka Satomi.

As Anzai clan which resided at west coast of Boso peninsula declined among this internal conflict, Yoshitaka Satomi placed Masaki clan which was close to Yoshitaka and held navy at east coast at Tsukuroumi castle and Kanaya castle, where directly faces Hojo navy at Miura peninsula. 

Yoshitaka won the internal conflict under the support of Hojo clan but soon broke with Hojo clan and attack their territory, thus Hojo clan made counter attack to east coast of peninsula by Hojo navy gradually expanded. Uraga Straight became the battlefield of both navy, and Tsukuroumi castle was strengthened as sea port of Satomi navy and watching place for Uraga Straight.

Structure of Tsukuroumi castle

Tsukuroumi castle is roughly “T” letter shape, which consists core areas spreads east and westward along the mountain and entrance from backside mountain at southward. Four areas are built in a line at the peak of mountain digging the rock into flat terrace, and corridor area are built at north slope of the mountain that faces the straight.

At the center of corridor area at north slope, there is a large hollow built by digging the rock. It is said as water moat, but there is no reason to build water moat at this place thus it might be a water source for the castle. At the west edge of the mountain, there is a large flat space facing the straight which was used as cannon place at the end of Edo era.

Southward of castle is naturally connected by narrow ridge to backside mountain. At the entrance of Torozaka Daishi temple on this backside mountain, huge hand built tunnel of over 10 meter height between fault exist and becomes photogenic sightseeing spot. Total size of the castle is 300 meter long and 50 meter wide, and relatively large one considering navy port castle.

Afterward of castle

Hojo clan and Satomi clan engaged in fierce battles from 1540’s to 1570’s at both of land and sea. At land Satomi clan had small territory and totally outnumbered by Hojo clan, but being supported by Satomi navy which made guerilla attack to Hojo army or town around Tokyo bay, Satomi clan barely stood against Hojo clan.

But in 1570’s, Satomi navy was also exceeded by Hojo clan, and there was no external power directly supported Satomi clan. Finally in 1577, Yoshihiro Satomi (1530-1578), son of Yoshitaka Satomi, agreed with Hojo clan which was virtually subordination of Satomi clan to Hojo clan.

Under this ally Satomi clan kept south part of Kazusa province then Tsukuroumi castle was still managed by Masaki clan. But in 1590, after the Odawara campaign of central ruler Hideyoshi Toyotomi (1537-1598) toward Hojo clan, Satomi clan lost Kazusa province then Tsukuroumi castle was abolished.

Over 250 years after that Edo Shogunate faces arrival of foreign warships to Tokyo bay which forced to open the nation. In addition to the cannons already built at Uraga area of Miura peninsula, Edo Shogunate built a battery at the remnant of Tsukuroumi castle, to made pincer attack to foreign ships. This time castle site was reformed with stone walls.

Today no building remains but structure of the castle well remains covered by bushes. The mountain is fully covered by trees and no scenery of straight, but at Takeoka ports at the side of the castle site many fishing vessels rest like the ships of Satomi navy in the past. Steam whistle of Tokyo-wan ferry heard at castle reminds this area had been an important crossing point of Tokyo bay, and also a battle field of two strong navies.

Continue to Part 5


30 minutes walk from JR East Uchibo-sen line Takeoka station. 15 minutes drive from Tateyama Jidoshado Futtsu-Takeoka interchange to parking space of Torozaka Daishi temple. Entrance of climbing road is at inside of temple.

Related Castles

Katsuura Castle - History of peninsular brave (3) Ally or subordinate?-
Mariyatsu Castle -History of peninsular brave (5) sudden fall of rival let way open-
Konodai Castle -History of peninsular brave (6) two time defeats at same battlefield-

Pictures (click to enlarge)

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