Wednesday, July 9, 2014

Ashigara Castle -Border barrier at Ashigara pass-

Ashigara Castle

-Border barrier at Ashigara pass-



Name: Ashigara Castle (Ashigara-jo)
Place: Takenoshita Oyama town, Shizuoka / Yagurasawa Minami-Ashigara city, Kanagawa
Location: 35.32013523348082, 139.0119322410136
Type: Mountain Castle
Built: Originally built in the former half of 16th century, expanded in 1580's
Remaining remnants: Clay walls and dry moats

Brief History

Ashigara castle (足柄城) is located at the top of Ashigara path, a path of 800 meter height above sea level at the north part of Hakone area and east of Mt. Fuji. Hakone area is a large caldera consist of 1,000 meter height mountains, and separates Sagami province (Kanagawa prefecture) and Suruga province (middle part of Shizuoka prefecture). 

To go to Kanto region from western area passengers have to pass the Hakone area by any route, and Hakone area had been a difficult path for communication of east and west area along the Pacific ocean.

Importance of Ashigara path

Currently main route of Hakone area is located at the west front of Hakone path, directly climb up from Mishima city to upper area along with current Route 1. This route was newly developed route after medieval era and suitable for movement of large parties, but passenger had to climb up and down steep slope. 

On the other hand, historically, passenger made detour to the north side of mountains along with current Route 246, and climb along the mountain stream and  passed Ashigara-toge pass. This was a narrow and more distant way but it was easy to move due to more gentle slope. This Ashigara-toge pass was a formal route of ancient Japan, and even after Hakone-toge pass way was developed still kept its position as an important route.

Historically the communication through Ashigara path was controlled by Ashigara path gate. In 15th centry, once Hojo clan seized Sagami province, Hakone area became the border of Hojo clan and Imagawa clan, a warlord of Suruga province. As Hojo clan was originally a retainer of Imagawa clan the relationship of both clan was generally good.

However, sometimes Hojo clan and Imagawa clan fiercely fought for east part of Suruga province, and in such case Hakone area became the front of both clan. In addition to this, a road from Kai province (Yamanashi prefecture) is connected to the north foot of Hakone area, and this area also was the border to Takeda clan, a warlord of Kai province.

Strengthening of Ashigara castle

These three clans once made alliance at Zentokuji temple in 1553 and border area became peace, but in 1568 Takeda clan attacked weakened Imagawa clan and occupied Suruga province, and tension arouse at this area again. 

As Odawara castle (Kanagawa prefecture), the main base of Hojo clan is only 20 km apart from Hakone area, security of Hakone area was vital matter to the clan. Hojo clan originally built a small castle at the path in the former half of 16th century, but facing this situation they reformed this castle in 1570’s.

Further in 1582, Takeda clan was extinguished by central ruler Nobunaga Oda (1534-1582) and central powers directly expanded to this area. Although Hojo clan allied with Ieyasu Tokugawa (1543-1616) who seized Suruga province in the same year, but Hojo clan had to guard their border more secure considering movement of Tokugawa clan or new ruler Hideyoshi Toyotomi (1543-1598). 

Structure of Ashigara castle

Under such circumstance, in the latter half of 1580’s Hojo clan made further improvement Ashigara castle, along with Yamanaka castle (Shizuoka prefecture) guarded front side of Hakone path and Kawamura castle (Kanagawa prefecture) which protected valley road of Sakawa-gawa river. Finally Ashigara castle became a huge fortress of 500 meter length. 

Ashigara castle is built at a place where the main ridge of Ashigara mountain starts from Kintokiyama mountain runs toward northeast and sub ridge used as a climbing route to the pass meets. Central area of Ashigara castle is a rectangular one of 50 meter long and 30 meter wide, stands just at the crossing point of ridges. 

Along with the sub ridge prolongs toward northwest, four terraces are built like a step. These terraces are separated by sheer slope, and outside of fourth terrace there is a combination of large dry moat and clay wall to protect the core area of the castle.  Ashigara pass road runs just below the line of these terraces, and enemy soldiers who tried to go through might be exposed severe attacks from upside.

Ahead of these terraces, small front forts were built by the place where Ashigara road climbs to this ridge. On the other hand, at the back of the central area there are many flat and large areas, which might be used of ground for residence of the lord, camping and storage space.

Odawara campaign and afterward

In 1590, central ruler Hideyoshi Toyotomi finally started Odawara campaign and attacked Hojyo clan by a large army. In march Toyotomi army directly siege Yamanaka castle in only half day, and promptly advanced to Odawara castle, the main base of Hojo clan. Due to this movement Ashigara castle lost its role and abandoned along with neighbor Kawamura castle.

Now due to the road improvement facilities of outer areas were lost, but shape of main areas well remain on the ridge. In fine days, the beautiful shape of Mt. Fuji is seen from the ruin of the castle.


90 minutes walk from JR East Gotenba-sen line Ashigara station. 15 minutes walk from Hakone-Tozan bus Ashigara-Manyo Koen bus stop (be careful for limited number of service). 30 minutes drive from Tomei Expressway Gotenba interchange.

Related Castles

Yamanaka Castle -Fortress guarded western border of Hojo territory-
Kawamura Castle -Closure of three roads-
Odawara Castle -Castle rejected attack of two famous warlords-


Pictures (click to enlarge)

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