Wednesday, October 17, 2018

Shizuhatayama Castle -Chancellor of clerical garment supported Imagawa clan-

Shizuhatayama Castle

-Chancellor of clerical garment supported Imagawa clan-



Name: Shizuhatayama castle (Shizuhatayama-jo)
Place: Oiwa-cho Aoi-ku Shizuoka city, Shizuoka
Location: 34.995261313829275, 138.37428731195618
Type: Mountain Castle
Built: 15th century
Remaining remnants: Clay walls and dry moats 

Brief History

Shizuhatayama castle (賎機山城) is located at Shizuhata-yama mountain at the northwest from center of current Shizuoka city. Shizuhata-yama mountain is a part of long and narrow hill which prolongs over four kilometer southward from Ryuso-zan mountain, along with main stream of Abe-kawa river. Around mountain there are ancient tomb or Shizuoka Sengen Shrine, and it had been the center of Shizuoka city for long time.

Prior to 17th century, Abe-kawa river did not merge to Warashina-gawa river, and ran the center of Shizuoka city from northwest to southeast. The shape of the roads at the center of Shizuoka city which run southward then turn to east but folded to southward again are the trace of old Abe-kawa river. Shizuhata-yama mountain and Abe-kawa river were exactly natural clay wall and water moat of medieval Sunpu city.

Origin of Imagawa clan

Precise year is unknown but Shizuhata-yama castle might be built by Imagawa clan, the governor of Suruga province (middle part of Shizuoka prefecture) in 15th century. Imagawa clan was originally a branch family of Kira clan, a local lord of Mikawa province (eastern part of Aichi prefecture) and close relative of Ashikaga clan which was one of the largest samurai group in Kamakura era.

In 1333, Kamakura Shogunate was ruined by an ally of Emperor Godaigo (1288-1339) and Takauji Ashikaga (1305-1358). But soon the both power became conflict concerning the rewards to Takauji and his supporters, then Takauji left Emperor and established his own Muromachi Shogunate. Emperor Godaigo was pushed out from Kyoto city and started the South Court at Yoshino area of Yamato province (Nara prefecture).

Among long continuing battles, Imagawa clan unchanged belonged to Takauji. Losing many leaders but Imagawa clan was appraised their contributions and became the governor of important provinces. Furthermore, Sadayo Imagawa (1326-1420), a relative of Imagawa clan was once appointed as the general governor of Kyushu island and captured island from South Court army.

Build of Shizuhatayama castle

However, being feared by third Shogun Yoshimitsu Ashikaga (1358-1408), Sadayo was suspected for rebel thus retired leaving Totomi province and Suruga province to main stream of Imagawa clan. Later Imagawa clan once lost Totomi province and held only Sugura province, thus it was respected as a major governor from its bloodline and military power.

Imagawa clan placed its main base at Sunpu city. Sunpu city had been the center of Suruga province from ancient period, but Imagawa clan renovated the city looking alike Kyoto city. Imagawa-yakata, the main residence of Imagawa clan might exist at current place of Sunpu castle, and a lattice shaped town was built from Imagawa-yakata toward north.

Imagawa-yakata was protected by Abe-kawa river flows just the south of the site, but in case of emergency it was necessary to build a castle on the mountain. There were Shizuhata-yama mountain and Yatsu-yama mountain at the west and east of the residence, but Shizuhata-yama castle is higher and sheer it was more appropriate to build a castle.

Structure of Shizuhatayama castle

Central area of the castle is an oblong shaped one of about 60 meter long and 20 meter wide, which is separated into several parts. Outer line of the area is surrounded by clan wall built by digging the inside, which is frequently used at the castles of Imagawa clan. Important area is a square shaped one of 20 meter long at the north edge of the part, and huge clay wall of this part might be used a basement of watchtower.

At the south of central area, a triangle shaped secondary area of about 50 meter long and 20 meter wide exists. This area is also encircled by clay wall, and south edge of the area is separated by deep dry moat of over 5 meter depth from outside. At the west ridge several terraces are built along the slope, and this might be used watching place toward west.

On the other hand, at the northwest of central area, third area which is a long and narrow area of about 50 meter long and 10 meter wide is built. At the north edge of the area there is a backside gate of the castle from northward. Total size of the castle is about 400 meter long and 100 meter wide, and its size and construction is suitable as a fortress of major governor.

Prince and his master

In the latter half of 15th century, Yoshitada Imagawa (1436-1476), the leader of Imagawa clan, tried to regain Totomi province but faced the resistance of local lords then died. After that, there arouse severe internal conflict for successor but Ujichika Imagawa (1471-1526) became next leader being supported by his uncle Nagauji Ise (1432?-1519, later Soun Hojo).

Ujichika captured Totomi province and transformed Imagawa clan into strong warlord but died early. His eldest son Ujiteru Imagawa (1513-1536) succeeded it but he was sickness, and one day died along with his younger brother. After that Imagawa clan again fell into severe conflict between Yoshimoto Imagawa (1519-1560) and Genko Etan (1517-1536).

As Yoshimoto was fifth son of Ujichika, he was not planned to succeed Imagawa clan and sent to the temple. His master at the temple was Taigen Soufu Sessai (1496-1555), the grand priest of Rinzai-ji temple and later became the chancellor of Yoshimoto then showed his multi talent at politics, military and diplomacy. 

Chancellor of clerical garment

At first Yoshimoto and Sessai lived at Kyoto city, but Ujiteru called them preparing for the conflict against Takeda clan, the warlord of Kai province (Yamanashi prefecture). But Ujiteru and his younger brother faced suspicious death, and Yoshimoto had to conflict with Genko Etan for next leader.

Facing this situation Sessai gathered retainers of Imagawa clan and support from Takeda clan and Hojo clan, then broke Genko Etan at the battle and forced to kill himself. Yoshimoto survived internal conflict established his authority, and Sessai became the chancellor of Yoshimoto. Yoshimoto opened Rinzai-ji temple for Sessai at the entrance gate of Shizuhata-yama castle, and this shows the trust of Yoshimoto to Sessai.

Meeting the trust of Yoshimoto, Sessai shows his talent both for diplomacy and military. Sessai coordinated with Takeda clan and made treaty between both clans, to compete with Hojo clan which became the enemy of Hojo clan. Later Sessai also coordinated with Hojo clan, and triangle treaty of three clans established in 1554 which secured eastern border of Imagawa clan and supported growth of three clans.

Peak of Imagawa clan

On the other hand, at Mikawa province (eastern part of Aichi prefecture), Imagawa clan struggled with Nobuhide Oda (1511-1552), a deputy governor of Owari province (western part of Aichi prefecture) and father of later ruler Nobunaga Oda (1534-1582). At first Nobuhide captured western half of Mikawa province, and also Nobuyasu Matsudaira (1543-1616), the successor of Matsudaira clan which was the governor of province.

In 1548, Sessai lead the army of Imagawa clan and broke Nobuhide at the battle of Azukizaka. Furthermore, next Sessai fell Anjo castle (Aichi prefecture) and captured Nobuhiro Oda (?-1574), then exchanged Nobuhiro with Nobuyasu Matsudaira. In this way Sessai pushed out Oda army from Mikawa province and captured it. 

By capturing Mikawa province, the territory of Imagawa clan approached to three provinces and becomes one of the largest warlords at that time. In addition to its territory, administration is managed under their house rule “Imagawa Kana-Mokuroku”, and Sunpu city economically prospered by commercial development. 

Sudden fall of Imagawa clan and afterward

Taigen Sofu Sessai brought peak period to Imagawa clan, but Imagawa clan also too much relied on Sessai. In 1555, Sessai died in ill, and no one could succeed the role of Sessai. The growth of Imagawa clan slowed down, and this gave time to Nobunaga Oda to unite Owari province prior to the arrival of Yoshimoto.

In 1560, Yoshimoto left for Owari province with large army to defeat Nobunaga, but faced sudden attack of Nobunaga at the battle of Okehazama and died in the battle. If Sessai still lived, Yoshimoto did not have to command the army at the front and Sessai could break the plot of Nobunaga. This was only five year after the death of Sessai.

Eight year after the death of Yoshimoto, after severe confusion Imagawa clan was ruined by an alliance of Shingen Takeda (1521-1583) and Ieyasu Tokugawa who left Imagawa clan and renamed from Nobuyasu Matsudaira clan. Shingen occupied Sunpu city mainly used Mariko castle for defense but might keep Shizuhatayama castle as a backup castle. After the fall of Takeda clan in 1582, Shizuhatayama castle might be abolished.

Today no building was left but structure of the castle well remain on the ridge. Now Shizuhata-yama mountain becomes a popular hiking course of local residents. From mountain scenery of Shizuoka city is well seen and this shown the importance of the castle for defense of the city. At its hillside Rinzai-ji temple still exist but mainly closed, and monks keep training following the teaching of great predecessor.


30 minutes walk from JR Central Tokaido Shinkansen line or Tokaido Honsen line Shizuoka station to Shizuoka Sengen Shrine, and another 30 minutes walk to castle site. 20 minutes drive from Shin-Tomei Expressway Shin-Shizuoka interchange to Shizuoka Sengen Shrine.

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Pictures (click to enlarge)

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