Saturday, June 20, 2015

Iwao Castle -Castle consist of two type stone walls-

Iwao Castle

-Castle consist of two type stone walls-



Name: Iwao castle (Iwao-jyo)
Place: Sannancho Tanba city, Hyogo
Type: Mountain Castle
Built: 1516
Remaining remnants: Stone walls, clay walls and moats 

Brief History

Iwao castle (岩尾城) is located at the park of Jyayama mountain, one of 350 meter above sea at Yamanami area where is south edge of Tanba city. Jyayama mountain spread its peak into four directions like a cross, and Iwao castle is built utilizing peak and southward ridge of the mountain. 

Yamanami area is a narrow valley along Kakogawa river, a large river flows into Harima province (south part of Hyogo prefecture). Because of its geographical condition, this area is a gate from Harima province into Tanba province (northwest part of Hyogo prefecture), and even now Kakogawa line which connects seaside area of Harima plain and Hikami basin or Fukuchiyama basin of Tanba province. Even though a small castle, it played an important role to guard the border.

Origin and development of Iwao castle

Iwao castle was built by local lord Hitoyori Wada in 1516. It is said that Wada clan was originally the local lord of Shinano province (Nagano prefecture), and moved to Yamanami area in the latter half of 15th century. Wada clan governed this area over about 100 years, but in 1579 this castle was attacked by Mitsuhide Akechi (1528-1582), a regional commander of central ruler Nobunaga Oda (1528-1582) who already beat major clan of Tanba province such as Hatano clan at Yagami castle or Akai clan at Kuroi castle. Iwao castle fell by Mitsuhide and Wada clan ruined. 

It is said that Iwao castle was abandoned for next several years. But considering its geographical condition and the fact that siege of Miki castle at the neighbor of this castle still continued for several months after the fall of this castle, this castle might be kept as a border castle.

In 1586, Hidekata Sano (?-?) was appointed as a lord of Iwao castle with small territory by central ruler Hideyoshi Toyotomi (1537-1598). Hidekata was originally a head of monk soldiers at Kido castle (Shiga prefecture) and fought against Nobunaga Oda, but was defeated and once hided. Later Hidekata served to Hideyoshi and became a lord. Hidekata reformed Iwao castle into a modern castle with stone walls. but in 1596 Hidekata returned to his native place Omi province (Shiga prefecture) and Iwao castle was abolished then.

Structure of Iwao castle

Iwao castle consist of hilltop area and terraces spread along with the ridge. Hilltop are was originally a long and narrow area of about 100 meter long and 30 meter width separated into north half and south half by narrow height at its center. But after the fall of Wada clan, north half of hilltop area was abandoned and only south half faces hillside area and castle town was reformed into modern castle.

At the center of south half there is a small main tower basement of 9 meter long and 6 meter wide, and two floor small tower might exist there. Central area is a 30 meter long square area surrounding main tower basement, and has folding gate at its west side. Secondary area covers southern and western line of the central area, and has its gate at its south part and northwest corner. 

At the west of these core areas there are two terraces named Nishinomaru and Demaru, and main route from hillside area connects at this place. Front side of Nishinomaru area there is a splendid stone wall of 3 meter high and 12 meter long.

Two type stone walls

Even though a small castle, but hilltop area is mostly covered by stone walls of two types. Stone walls of central area and secondary area are not so high and built using same size round stones, without clear corner structure. This style of stone walls resembles to stone walls at mountain castles built by Mitsuhide Akechi, such as Shuzan castle (Kyoto prefecture). 

On the other hand, stone wall of main tower basement or front wall Nishinomaru area where is the main gate of the castle and guarding turret might exist are tall and built by rough and large stones. Furthermore there are clear corner structure named "Sangizumi", the way to place rectangular solid stone alternately at 90 degree different direction, like a Jenga toy. This structure is a newly developed method to prevent corruption of stone wall, and seen at stone walls after the middle of 1580's. 

It is thought that at first Akechi clan built low stone walls of outer area to strengthen this castle as a border fortress, and later Sano clan built added main tower basement and front gate wall to show it authority as a lord. Outside of hilltop area, narrow and long terraces spread along the ridge till hillside area, and Shinnenji temple just beside the mountain is said as a place of former hillside residence of the lord.

Now all building was lost but half broken stone walls still remain at the peak of the mountain. Height difference between hillside area and hilltop area is nearly 300 meter and it is a bit tough to climb to the castle, but it is used as a hiking course of local people and if weather is fine beautiful scenery is seen from the castle. Even though small, many elements are condensed at this castle and worth for visiting. 

Important notice:

To climb up to the castle, it is necessary to pass the ground of elementary school (former main route start at the behind of Shinnenji temple but difficult to find), and because of school security it is necessary to get permission to pass thought the school in weekdays. It is strongly recommended to visit this castle in holiday.

Related Castles

Pictures (click to enlarge)

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