Japan Castle Explorer: Hiebiyama Castle -Three castles at misty basin (1)-

Hiebiyama Castle

-Three castles at misty basin (1)-

Overview

Name: Hiebiyama castle (Hiebiyama-jo)
Alias:
Place: Ushiroyama-cho Miyoshi city, Hiroshima
Type: Mountain Castle
Built: 14th century
Remaining remnants: Stone walls and clay walls
Title:

Brief History

Hiebiyama (比叡尾山城) castle is built over hilltop area of Hiebi-yama mountain, one of about 220 meter from hillside at 3 kilometer east from current Miyoshi city center. Castle site is at the north edge of Miyoshi basin, which is a parallelogram one of about 20 kilometer spreads in the north part of current Hiroshima prefecture.

Miyoshi basin is formed by Gono-kawa river and its tributaries. As Gono-kawa river flows passing Chugoku mountains which separates Chugoku region into Seto-Naikai sea side and Sea of Japan side, this area has been the center of communication in the western half of Chugoku region. North edge of the basin is a line of sheer cliff formed by active fault, and it is an advantage to build castles for both of defense and scenery.

Origin of Miyoshi clan and Hiebiyama castle

Precise year is unknown but Hiebiyama castle might be built by local lord Miyoshi clan in 14th century. Miyoshi clan is said as a descendant of central noble Fujiwara clan and moved to their manor Miyoshi area in medieval era. Miyoshi area belonged to Bingo province (east half of Hiroshima prefecture) but apart from its center at coast area, Miyoshi clan grew as an independent local lord.

After the fall of Kamakura Shogunate in 1333, Chugoku region was involved into struggle between Muromachi Shogunate and their opponent the South Court or Tadafuyu Ashikaga (1327?-1387?). As neighbor large lords such as Yamana clan or Ouchi clan at first supported the South Court and Tadafuyu Ashikaga, Miyoshi clan also opposed to Muromachi Shogunate.

But because of the plot of Muromachi Shogunate, Ouchi clan and Yamana clan turned to Muromachi Shogunate, then became the governor of east half and west half of Chugoku region under Muromachi Shogunate respectively. Miyoshi clan followed this movement and became a local lord under Yamana clan which became the governor of Bingo province.

Yamana clan once seized one sixth of Japan and became largest retainer of Muromachi Shogunate, but significantly decreased their power at the battle of Meitoku, a subjugation by Shogunate in 1391. Later Yamana clan recovered their power again but exhausted at the battle of Onin and internal conflict then fell into small power by the end of 15th century. Bingo province was nominally a territory of Yamana clan but local lords separately governed their territory.

On the other hand, Ouchi clan also gained large territory and was once subjugated by the Shogunate, but later recovered their power then became the strongest governor in the western half of Japan, controlling Hakata port. Their original territory was Suo province and Nagato province (Yamaguchi prefecture) but controlled Aki province (western half of Hiroshima prefecture) and tried to advance into Bingo province, to secure marine transportation route at Seto-Naikai sea.

Two strong powers of Chugoku region

At the same time, at Izumo province (eastern half of Shimane prefecture) at the north of Bingo province, Amago clan overcame Kyogoku clan which was the governor of the province and became strong warlord under their intelligent leader Tsunehisa Amago (1458-1541). Amago clan which united Izumo province aggressively expanded their territory into southeastward, and also struggled against Ouchi clan for regional hegemony.

North half of Aki province and Bingo province became the border of two strong power. Small local lords of these areas including Miyoshi clan or Mouri clan, the lord of Yoshida Koriyama castle (Hiroshima prefecture), moved between two power, cooperating or conflicting each other, Especially Miyoshi clan directly faced Mouri clan, as their territories were directly connected by Gono-kawa river.

In 1540, Amago clan sent large army to Yoshida Koriyama castle to ruin Mouri clan. But facing secure guard of Mouri clan and counter attack of reinforcement army from Amago clan, Amago clan suffered fetal defeat and retreated. At this time Miyoshi clan supported Amago clan but turned to Ouchi clan looking at the defeat of Amago clan.

Between two strong powers

Two years later this time Ouchi clan sent large army to Gassan Toda castle, the main base of Amago clan to ruin them. But Ouchi clan also stalled at secure Gassan Toda castle then faced estrangement of local lords once turned to Ouchi clan, then also suffered severe defeat. Amago clan left its crisis regained their power, and started to expand again.

At this time Yamana clan at Kannabe castle (Hiroshima prefecture) at coast area belonged to Amago clan, but Miyoshi clan did not turn to Amago clan along with Mouri clan. In 1544 Amago clan sent their strong troop Shingu-to army to Bingo province, to ruin Miyoshi clan besieged at Hiebiyama castle.

Miyoshi clan requested reinforcement army to Motonari Mouri (1497-1571), the leader of Mouri clan, and Motonari sent their important retainers as reinforcement army. Miyoshi army and Mouri army fought against Amago army stayed near Hiebiyama castle but suffered severe defeat which named as “Fuse Kuzure”.

Miyoshi clan losing their army and reinforcement army was forced to the corner. But in this fatal crisis Munetaka Miyoshi (?-?), the leader of Miyoshi clan, made sudden attack to Amago army with small army. Amago clan became loosen after the victory fell into confusion by this attack then retreated to Izumo province.

Relationship with Mouri clan

After that Amago clan aimed eastern area such as Mimasaka province (north part of Okayama prefecture) or Harima province (western half of Hyogo prefecture), and Mouri clan gradually grew their power to Bingo province. To confront against Amago clan, Miyoshi clan closer approached to Mouri clan, sending their lady as a concubine of Motonari.

In 1551, Yoshitaka Ouchi (1507-1551), the leader of Ouchi clan, was defeated by a coup d’?tat by his deputy governor Harukata Sue (1521-1555). Motonari at first supported Harukata but later broke and defeated Sue army at the battle of Itsukushima next year. Now Motonari overcame Ouchi clan and Sue clan became the ruler of western half of Chugoku region and challenged to Amago clan which seized middle part of Chugoku region.

Haruhisa Amago (1514-1561) who seized Iwami silver mine well stood against the attack of Mouri clan and broke Mouri army several times. But after the sudden death of Haruhisa Amago clan fell into confusion and significantly lost their power, and finally surrendered to Mouri clan in 1566. Now Mouri clan seized whole part of western part and middle part of Chugoku region and became the ruler of the area.

Motonari placed his second son Motoharu Kikkawa (1530-1588) as the commander of the Sea of Japan side, and third son Takakage Kobayakawa (1533-1597) as the commander of Seto-Naikai sea side. Miyoshi basin is an important route to connect both area from Yoshida Koriyama castle, the main base of Mouri clan, thus Hiebiyama castle was expanded to protect this important route.

Structure of Hiebiyama castle

Central area of Hiebiyama castle is L shaped area of about 80 meter long and 40 meter wide, at the peak of the mountain. Its backside is protected by clay wall which might be used as a basement of main building, and its front side is protected by stone wall which has stone built steps. Corridor area surrounds whole part of central area, which is separated by line of stone wall.

At the south of central area, secondary area and third area are built in line utilizing a line of ridge. Utilizing height difference these area are separated by tall clay wall and dry moat. Especially the third area at the south edge of core part is divided from front side fort by over 10 meter deep and wide huge dry moat.

At the east of core areas, utilizing flat area at the saddle point to next mountain, flat areas were built for residence and storage space. A large area separated by line of stone wall might be a ground of the residence of the lord, and ruin of pond and waterline built by stone wall still remain near them. Total size of the castle is about 400 meter long and 300 meter wide, and its size and structure shows importance of this castle to Mouri clan.

Relocation of castle and afterward

After the fall of Amago clan, except for short term when Amago restoration army intruded into Izumo province, Miyoshi basin was apart from battles. Mouri clan continued expansion under Motoharu Kikkawa and Takakage Kobayakawa, but Miyoshi clan were not recorded in their battle and might closely worked for main family of Mouri clan at Yoshida Koriyama castle.

By the middle of 1570’s Mouri clan expanded their territory to whole part of Chugoku region, but had to face the attack from central ruler Nobunaga Oda (1534-1582). Mouri clan gradually lost their territory before Hideyoshi Hashiba (1537-1598, later Hideyoshi Toyotomi) who was a regional commander of Nobunaga, but after the sudden death of Nobunaga in the incident of Honnoji in 1582, Mouri clan made peace with Hideyoshi and survived as feudal lord.

Under the stabilization of their status and change of territory, Mouri clan reorganized their retainers with castles. They moved their main base from Yoshida Koriyama castle to Hiroshima castle built in 1591 which can manage Hiroshima bay directly. At the same year Miyoshi clan also moved their main base from Hiebiyama castle to Higumayama castle (Hiroshima prefecture) at 5 kilometer west, which could directly control Gono-kawa river and riverside roads.

Now no building remains but structure of the castle well remain over the mountain. At the both side of castle traditional Kumano Jinja Shrine and Iwaya-dera temple exist and shows this place had been a main base of traditional local lord. Because of its weather condition Miyoshi basin frequently covered by mist, and castle site looks down the basin from above of the mist same as old time.

Access

10 minutes drive from Chugoku Jidoshado Expressway Miyoshi-Higashi interchange to Kumano shrine. 30 minutes walk from Shrine to hilltop castle. Forest roads from Iwayadera Temple is connected to just below of castle but closed as of December 2018.