Sunday, October 20, 2019

Konosumiyama Castle -10 year battle at capital city for the purpose of battle itself-

Konosumiyama Castle

-10 year battle at capital city for the purpose of battle itself-



Name: Konosumiyama castle (Konosumiyama-jo)
Place: Izushicho Toyooka city, Hyogo
Location: 35.48749306479056, 134.8703032991334
Type: Mountain Castle
Built: 15th century
Remaining remnants: Clay walls and moats 

Brief History

Konosumiyama castle (此隅山城) is located over Konosumiyama hill, one of about 100 meter height from hillside at 2 kilometer north of current Izushi city central. Izushi area is a small basin spreads over 3 kilometer from south east edge of Toyooka basin, and castle site locates at middle part of Izushi basin.

Toyooka basin is a large one of about 12 kilometer long and 3 kilometer wide, and had been the economic and agricultural center of Tajima province (north part of Hyogo prefecture). Sanin-do Road which connected Kyoto city and Sanin area passes mountainous area at the south of Toyooka area.

But for the transportation of supplies and movement of army coastal road passes Toyooka city and Kami town, which is the route of Sanin Honsen line, might be used. This meant Toyooka area also had been the center of communication of the province.

Origin of Yamana clan

Konosumiyama castle might be built by Yamana clan, the governor of Tajima province in 14th century. Yamana clan was originally a small branch family of Nitta clan, a traditional and major samurai of Minamoto clan at Kozuke province (Gunma prefecture). At the establishment of Kamakura Shogunate, Yamana clan belonged from early period and contributed.

After the fall of Kamakura Shogunate in 1333, Emperor Godaigo (1288-1339) and Takauji Ashikaga (1305-1358) once cooperated to defeat Shogunate broke, then Takauji built his own Muromachi Shogunate at Kyoto city. Yoshisada Nitta (1301-1338), the leader of Nitta clan, belonged to the Emperor side and became its military commander , but after various battles Yoshisada died in the battlefield and Nitta clan significantly declined.

On the other hand, Yamana clan had marital relationship with Ashikaga clan then followed to Muromachi Shogunate. Yamana clan activated at various battles and acquired the position of governor of Sanin provinces, and became of one of the four clan which have qualification to be the minister of "Samurai Dokoro", the military and police office of the Shogunate. 

"One-sixth lord" of Japan

After that on the internal conflicts in the Shogunate, Yamana clan raised their army against Muromachi Shogunate, and once occupied shortly Kyoto city and expanded their territory defeating governors of neighbor provinces. But after a negotiation with Shogunate, finally Yamana clan turned to Shogunate with the governor position of 11 provinces. As the number of total province was 66, Yamana clan at that time was called as "One-sixth lord".

However, Yoshimitsu Ashikaga (1358-1408), the third Shogun, feared the power of Yamana clan intervened to the internal conflict of Yamana clan to decrease their power. Furious Yamana clan raised their army against Shogunate in 1391 and once captured Kyoto city but was finally defeated, then the territory of Yamana clan once decreased to four provinces.

After that, this time Yamana clan contributed in the conflicts between the Shogunate and other major governors such as Ouchi clan or Akamatsu clan, then achieved the governors of middle part of Chugoku region. Now Yamana clan became the governor of huge territory spreads west edge of Kinki region and east half of Chugoku region, and became second position in Shogunate next to Hosokawa clan, which was a relative of Shogunate and placed as general minister "Kanrei" position with large territory. Yamana clan expanded Konosumiyama castle as the main base of the clan.

Structure of Konosumiyama castle

Konosumiyama castle consists of many small terraces spreads over three ridges continue from the peak. Central area of the castle is a rectangular one of about 20 meter long and 10 meter wide. At the south of central area, small terraces were built along with the ridge like steps, and a line of terraces diverges toward west to Senjojiki area, a large entrance area from hillside residence area.

Contrary to southward, line of terraces spreads toward northwest from central area is securely protected by combination of dry moats and clay walls. Terraces of this part are comparatively larger than other area and have sheer wall, and this part might be renovated to improve security in the latter half of 16th century. There is another line of terraces at northeast but it is covered with bush and difficult to enter.

Between two ridges of western slope, there might be a hill side residence of 300 meter long and 200 meter wide. At the hill opposite of road from castle, line of terraces is built like a clay wall. Total size of core area is about 600 meter long square and exceeds 1,000 meter including outer forts, and it shows the power of Yamana clan as the second largest governor of Shogunate. 

Fuse to long time battle

Originally Sozen Yamana (1404-1473), the leader of Yamana clan, and Katsumoto Hosokawa (1430-1473), the leader of Hosokawa clan, were marital relative and cooperated. But as a general minister of Shogunate, Katsumoto had to decrease the power of Yamana clan, then gave the territories of Sanin region such as Harima province (Hyogo prefecture) or Bizen province (south part of Okayama prefecture) to Akamatsu clan, which was once ruined by an assassination of sixth Shogun Yoshinori Ashikaga (1394-1441).

In the middle part of 15th century, Muromachi Shogunate was a coalition government of several major governors. Muromachi Shogunate tried to weaken their power and intervened, but as Shogunate had only small guard it was necessary to involve other governors into military operation. Major governors had several provinces then placed branch families on each territory thus Shogunate tried to change the leader of the governor to more obedient one, but this brought endless internal conflict to each governor and antipathy to Shogunate.

Amid that situation, an internal conflict occurred at Shogunate itself. The 8th Shogun Yoshimasa Ashikaga (1436-1490) who once lost his son adopted his younger brother Yoshimi Ashikaga (1439-1491) as a successor in 1464, but next year Yoshihisa Ashikaga (1465-1489) was born. Tomiko Hino (1440-1496), the wife of Yoshimasa, hoped to place her son Yoshihisa to Shogunate and suppressed Yoshimi. Katsumoto supported Yoshihisa from the stability of successor, but Tomiko approached to Sozen to support Yoshihisa.

Lead to outbreak of battle

In 1466, Shogun Yoshimasa Ashikaga suddenly changed the leader position of Shiba clan, an another major governor house which served governors at the east of Kyoto city. In response to this, Sozen who had relationship with former leader protested to Yoshimasa, then the leader position returned to the original status.

At the same time, Hatakeyama clan which had territory at the south of Kyoto city and Hokuriku region also had the internal conflict. Yoshinari Hatakeyama (1437-1491) once chosen by the leader from Yoshimasa Ashikaga, but later Yoshimasa expelled Yoshinari and placed his cousin Masanaga Hatakeyama (1442-1493). Yoshinari once escaped and waited the chance for recovery, under the support of Sozen Yamana.

In 1465, Yoshinari raised his army and captured castles of Yamato province (Nara prefecture) next year. Furthermore, Yoshinari marched to Kyoto city in 1467, and merged with the army of Sozen Yamana. They suppressed Yoshimasa Ashikaga by their army and returned the leader position of Hatakeyama clan. To face this situation, Katsumoto Hosokawa and his supporter gathered their army then the long battle of Onin started at capital city.

Process of battle

Katsumoto and Sozen gathered their army from territory. Yamana army of 20,000 soldiers were summoned at Konosumiyama castle then marched to Kyoto city. It is recorded that the East army lead by Katsumoto Hosokawa had 160,000 soldiers, and the West army commanded by Sozen Yamana held 110,000. It was a huge battle from the fall of Kamakura Shogunate, and the peak of Yamana clan.

As current Shogun and Imperial Household were kept by the East army, the West army did not have legitimacy. The West army also hold less number of soldiers, but Ouchi can which was the wealthy governor of Suo province (Yamaguchi prefecture) which monopolized foreign trade with the continent supported Sozen and sent large army, and Ouchi army was stronger than mixed-up Eastern army.

Shogun Yoshimasa Ashikaga was originally at East army as West army had a character of rebel for the Shogunate, but Yoshimasa gave up the settlement of situation and half retired. On the other hand, Yoshimi Ashikaga turned to the West army then the West army increased their political legitimacy. Thus political solve of this battle also became difficult.

Continuation of meaningless battle

Continuation of the battle at capital gave severe damage to Kyoto city and Shogunate. Houses were burnt down, and foods were deprived by collection of both armies and thieves. Shogunate could not solve the battle at their own capital clearly shows loss of authority and power, and even Imperial Household could not earn money for operation, by lost of their manors.

During long battle, as leader of each governor house had to stay at Kyoto city, they delegated their roles to deputy governors. In the long absence of the governors and internal conflicts in their territory, deputy governors gradually grasped administration and army of the province then started to surpass governors. As major governors gather at Kyoto city had several provinces throughout west half of Japan, the disturbance of war spread to wide area.

After 1570, both army only fought from force of habit, because of lack of clear target and strategy, as if the purpose of the battle is the battle itself. In 1471, Takakage Asakura (1428-1481), a substantial founder of Asakura clan as the warlord of Echizen province (Fukui prefecture) and worked as the West army, turned to the East army to deprive the province from its governor Shiba clan belonged to the West army.

Unsatisfactory end of 10 year battle

In the inferior situation of the West army, in 1473 both of Katsumoto Hosokawa and Sozen Yamana died in the ill, but even loss of leaders could not stop the battle. On this occasion the Shogunate tried to coordinate both side but failed, and this showed the total loss of authority of Shogunate. Finally Ouchi clan and Shogunate made peace in 1477 then Ouchi army returned to their territory, thus the West army disappeared and 10 years battle finished at last.

This long battle called as the battle of Onin from its era name brought no reward to all participants. For Yamana clan, it could not recover economically developed provinces of Sanyo region, and long time military operation was a significant burden to its territories. Local lords gained their power started to rebel against Yamana clan, and Yamana clan had to accepts their demands.

Around 1500, Yamana clan fell into small clan only to manage Inaba province (Tottori prefecture) and Tajima province. In Tajima province, four local lords such as Kakiya clan or Otagaki clan, thus Yamana clan kept only nominal authority. In the middle part of 16th century, Suketoyo Yamana (1511-1580) broke local retainers and temporally restored Yamana clan as the warlord. 

Fall of Yamana clan and afterward

But in 1569, Hideyoshi Hashiba (1537-1598, later Hideyoshi Toyotomi) who was the commander of central ruler Nobunaga Oda (1534-1582) attached Tajima province. Suketoyo Yamana could not protect Konosumiyama castle before overwhelming Oda army, then once escaped to Sakai city but later was forgiven and subordinated to Oda clan in 1570.

Suketoyo moved his main base to current Izushi area and built Arikoyama castle (Hyogo prefecture), secure castle at higher placed compared with Konosumiyama castle. But at the conflict between Oda clan and Mouri clan in the latter half of 1570's , the warlord of Aki province (Hiroshima prefecture) and spread its territory to whole part of Chugoku region, important retainers of Yamana clan chose Mouri clan thus Yamana clan itself was regarded to change to Mouri clan.

In 1580, Hideyoshi Hashiba who solved rebellion of Miki clan at Miki castle (Hyogo prefecture) sent large army to Arikoyama castle. Suketoyo Yamana opened the castle and died in ill just after that, and Toyokuni Yamana (1548-1626), cousin of Suketoyo and lord of Tottori castle (Tottori prefecture), also surrendered to Hideyoshi at that year. The history of Yamana clan as the governor or warlord had ended. 

Now no building remains but structure of the castle well remain over the hill. Over all old style which is the combination of small terraces and large size of the castle well shows the glory days of Yamana clan which was once a "One-sixth lord" and leader of the West army of huge battle. On the other hand, partial renovation to add defense facility indicates tough situation of Yamana clan that lost many things and had to face an overwhelming enemy at its main base.  


30 minutes drive from Kita Kinki-Toyooka Jidoshado Expressway Hidaka-Kannabe interchange. Entrance of climbing road is at backside of the museum.

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Pictures (click to enlarge)

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