Thursday, October 15, 2015

Tsukui Castle -Mountain castle with forest, lake and flower-

Tsukui Castle

-Genuine mountain castle close to Metropolis-



Name: Tsukui castle (Tsukui-jo)
Place: Negoya Midori-ku Sagamihara city, Kanagawa
Type: Mountain Castle
Built: Unknown
Remaining remnants: Stone walls, clay walls and moats 

Brief History

Tsukui castle (津久井城) is located at Shiroyama mountain, one of about 200 meter height from hillside at the next of Lake Sagamiko in Sagamihara city, which locates at the northeast border of Kanagawa prefecture.

Tsukui area exists at the border of Tanzawa mountains and Kanto plain, and now it becomes large lake because of dam construction but formerly it was a narrow valley in the forests along with Sagamigawa river, a large river flows from mountainous area of Eastern Yamanashi prefecture to the middle part of Kanagawa prefecture. 

Genuine mountain castle close to Metropolis

Tsukui area is a crossing point of east and west bound roads to Kai province (Yamanashi prefecture) as a bi-pass road of Koshukaido road, and north and south bound road connecting Hachioji city and Hiratsuka city. Furthermore, Sagamigawa river is use as a method of river transportation from sea to Tsukui area, where is the connecting point of river transportation and marine transportation. 

Tsukui area is one of the closest mountainous area from Tokyo metropolis within 60 minutes drive, thus now used as good nature park for metropolitan people. But this also means that it is a critical point for the holder of Kanto plain against the attack from westward.

Especially for Hojo clan which was the ruler of Kanto region and held their main base at Odawara castle only 30 kilometer apart from Tsukui castle, it was a fear that the intruder from Kai province could advance along with Sagami-gawa river and could isolate Odawara castle from other part of Kanto region.

Because of its geographical location, Tsukui castle had been an important point to control the border between Kai province (Yamanashi prefecture) and Kanto region, along with Hachioji castle (Tokyo metropolis) watches Koshu-kaido road and Jofukuji castle aside Jinba-kaido road.

Origin of Tsukui castle

Precise year is unknown but it is said that Tsukui castle was built by Tsukui clan which was a branch family of Miura clan in medieval era. Later Tsukui castle was held by Naito clan, which was a local lord originally served to Ogigayatsu Uesugi clan. But along with the rise of Hojo clan which was the lord of Odawara castle (Kanagawa prefecture), Naito clan turned to Hojo clan and became its important retainer.

At the beginning of 16th century, Oyamada clan which was the lord of Iwadono castle (Yamanashi prefecture) at the next of Tsukui area, had relationship with both of Takeda clan which was the lord of Kai province and Hojo clan thus worked as a buffer zone. But later Oyamada clan was attacked by Takeda clan and subordinated to Takeda clan. Tsukui area became a new border between Hojo clan and Takeda clan, and thus Tsukui castle was strengthened as a border castle by Hojo clan.

Structure of Tsukui castle

Tsukui castle is built using hilltop and hillside area of Shiroyama mountain. As it is difficult to grasp because of dam lake, originally Shiroyama mountain places at river height of Sagamigawa river between mainstream and tributaries of Sagamigawa river. This mountain has a beautiful conical shape western half and triangular pyramid shaped eastern half like a water drop at plain view. 

Hilltop area roughly consists of eastern and western peak and a 200 meter long and narrow path connects them. Central area of the castle is a 40 meter long square shape area at the western peak, and being surrounded by several terraces. Two gates into western peak is reformed into Masugata style combined gate which is an advanced style, and stone walls surrounded central area remain at terraces built at its western slope. 

Another peak at eastern part also consists of several terraces and is now used as a ground of Izuna shrine. At the entrance of this area there is a small flat area works as a porch of the road from hillside, and there still remains a well filled with water. Ahead of this peak, another small peak named Okariba which is used as a watching point toward east. A long ridge connects both peak is used as a path connecting them, and just before the western peak there is a ruin of wooden bridge over a dry moat, which was planned to be destructed in case of emergency. 

Residence and castle town at hillside

At the western hillside of mountain which is surrounded by mountain and river, vast terraces spreads about 500 meter long and 200 meter wide. These terraces were used as residences of lords and retainers at peace time, and also might work as a defense line being guarded by deep valley then they are substantially a part of the castle. 

A saddle height connects Shiroyama mountain and next mountain is also used as a residence of lower retainers, and castle town might spread at the flat space between the mountain and Sagamigawa river now sunk into dam lake. When we look at only hilltop area it seems too small as a border castle faced strong powers, but considering whole structures including hillside area this castle might be a sufficient defense ability. 

Battle of Mimasetoge pass

In 1554, Hojo clan, Takeda clan and Imagawa clan which was the lord of Suruga province (eastern part of Shizuoka prefecture) made a triangle alliance thus the border between Sagami province and Kai province kept calm over 10 years. But in 1567, Takeda clan broke the treaty and invaded into Imagawa territory. As Hojo clan still supported Imagawa clan, Takeda clan and Hojo clan became hostile. To suppress Takeda clan, Hojo clan made alliance with Uesugi clan which was the lord of Echigo province (Niigata prefecture) and fatal rival of Takeda clan.

In response to this attitude of Hojo clan, in 1569, Shingen Takeda (1521-1573) lead a large army and intruded into Hojo territory. After demonstrative attack to Hachigata castle (Saitama prefecture) and Takiyama castle (Tokyo metropolis) which were major branch castles of Hojo clan held by sons of Hojo family, Shingen turned his army to Odarawa castle, the main base of Hojo clan. 

Odawara castle was a huge castle which rejected fierce attack of Kenshin Uesugi (1530-1578) who was praised as a god of war. As the purpose of this attack was to tear the alliance between Hojo clan and Uesugi clan then bring Hojo clan to his side, Shingen surrounded Odawara castle only 5 days and departed for Kai province passing Atsugi city and moved northward.

Hojo clan tried to capture retreating Takeda army before the border and already sent reinforcement army lead by Ujikuni Hojo (1541-1597) and Ujiteru Hojo (1540-1590) to Mimasetoge pass, only one mountainous route from middle part of Sagami province to Kai province passing beside Tsukui area. At the same time, main force of Hojo clan was planned to sally from Odawara castle and tried to attack Takeda army from behind. 

But cooperation of Hojo army was not good and detached force attacked Takeda army only by themselves. At first Hojo clan bravely fought from upside and ruined Nobutane Asari (?-1569), a general of Takeda army, but detached force of Takeda army lead by Masakage Yamagata (1524-1575) attacked Hojo army from further backward and finally defeated Hojo army before the arrival of main force then could return to Kai province.

Preparation for central power and fall

In 1571, Hojo clan and Takeda clan allied again, but in 1582 Takeda clan was ruined by central ruler Nobunaga Oda (1534-1582). After the death of Nobunaga in the incident of Honnoji at that year, Hojo clan struggled for Kai province against Ieyasu Tokugawa (1543-1616), former ally of Nobunaga and lord of Suruga province, but finally Kai province was held by Tokugawa clan. Even though Tokugawa clan and Hojo clan allied, Tsukui castle was further strengthened as an important border castle. Stone walls intensively built at western half might be constructed at this time toward west.

In 1590, at last, next central ruler Hideyoshi Toyotomi (1537-1598) who already subdued Ieyasu Tokugawa started expedition from west against Hojo clan. In June, just after the fall of Hachioji castle next to Tsukui castle, Tsukui castle was attacked by Tokugawa army and fell. As lord of the castle and major part of guardians besieged at Odawara castle, only small number of soldiers might stay at the castle. Hearing the news of the fall of Hachioji castle, Tsukui castle might be opened bloodlessly.

After the fall of Hojo clan, Tokugawa clan became the lord of Kanto region and Tsukui area became the directly governed territory of Tokugawa clan. Tsukui castle was abolished, and an administrative office was built at hillside area. But this office was later abolished in 1644 and Tsukui area was governed from Nirayama administrative office.

Afterward of castle

Now Shiroyama mountain is improved as a natural park, and utilizing a combination of beautiful shaped mountain, lake and forest it becomes a famous natural playing spot for Tokyo city people. Visitors can enjoy flowers in spring, water playing in summer, and red leaf in autumn. Structures of castle is well kept on mountain, and in winter shape of the castle including slightly remaining stone walls is well seen. Access to the castle is good by car, and it is a good place to visit both for castle visiting and nature enjoyment.


10 minutes drive from Kenodo Expressway Sagamihara interchange. Shiroyama-Koukoumae bus stop of Kanagawa-Chuo bus from JR East / Keio line Hashimoto station. 30 minutes walk from hillside entrance to hilltop castle.

Related Castles

Hachioji Castle -Plaee of final battle for unification by Hideyoshi-
Jofukuji Castle -Castle up and down like roller coaster-
Takiyama Castle -Expansion and limitation of medieval castle-
Odawara Castle -Huge medieval castle rejected attack of two strong warlords-

Pictures (click to enlarge)

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