Year: Tenbun 12 (1543) to 9/4 of Tenbun 18 (1549)
Location: The environs of Kannabe Castle in southern Bingo Province
Outcome: The combined forces of the Ōuchi and Mōri prevailed with Yamana Tadaoki abandoning the castle and fleeing.
The Kannabe Conflict, which occurred from the sixth month of Tenbun 12 (1543) to 9/4 of Tenbun 18 (1549), consisted of a series of battles waged between the combined forces of the Ōuchi and Mōri clans against Yamana Tadaoki, an ally of the Amago clan. The conflict centered upon efforts to control Kannabe Castle in Bingo Province. After a six-year period, the Ōuchi and Mōri prevailed, while Tadaoki abandoned the castle and fled. At the time of this conflict, the site was named Murao Castle, while the name of Kannabe was adopted after the end of the sixteenth century.
Yamana Tadaoki, a powerful kokujin, or provincial landowner, in Bingo Province was based in Kannabe Castle in the Yasuna District and, together with the Ōuchi clan, exercised control over the littoral region in the southern portion of Bingo. However, in the fifth month of 1543, the Ōuchi army was defeated in an expedition to Izumo Province (the home base of the Amago clan) in an event known as the First Siege of Gassantoda Castle. Tadaoki then switched his loyalties from the Ōuchi to the Amago and came into conflict with the Ōuchi forces.
While serving as a rear guard for the Amago, Tadaoki sought to continue to expand his power whereupon he targeted the Numata-Kobayakawa clan who had lost their lord in the expedition to Izumo. This triggered a counterattack by the Ōuchi army and Mōri Motonari, the most powerful kokujin in Aki Province.
Outbreak of hostilities
In the sixth month of 1543, Tadaoki took quick action, leading troops to Mukuna in the Numata-Kobayakawa territory. However, the Mōri army deployed as reinforcements, blocking an attack by the Yamana army. In the seventh month, the Mōri further came to the aid of Hironaka Takakane, a senior retainer of the Ōuchi stationed at Tsuchiyama Castle in Aki. In the tenth month, Amago forces who came in support of the Yamana were repelled so the Ōuchi and Mōri armies went on the offensive and, by the end of the year, advanced to the stronghold of Kannabe Castle. Tadaoki succeeded in defending the castle, but battles in Kannabe began from this year while the contest for the castle turned into a prolonged conflict.
In 1544, with the aim of supporting Yamana as the bridgehead for the invasion of Bingo by the Amago clan, in the third month, the Amago army advanced to Tabusa in the Kōnu District, and, in the seventh month, to Funo in the Futami District (in an event known as the Collapse at Funo), and, in the tenth month, to Takayama Castle in the Toyota District. None of these advances, however, yielded results.
Isolation of Kannabe Castle
In the eleventh month of 1544, the third son of Motonari named Tokujumaru (later known as Kobayakawa Takakage) became the head of the Takehara-Kobayakawa family and the Kobayakawa clan became members of the Mōri family. Preceding this event, around the eighth month, the Ōuchi instructed the Takehara-Kobayakawa to take control of five manors to the southeast of Kannabe Castle, including Ōmon, Hikino, Noshima, Nonohama, and Tsunoshita, and to build castles in these locations. At the time, the harbor in Ōmon Bay was a relay point for Amago forces in Bitchū Province so the objective was to attack from the sea with the naval forces of the Kobayakawa.
In 1546 or 1547, the Takehara-Kobayakawa army toppled Teshirojima and Akechiyama castles in the environs of Ōmon Bay and succeeded in establishing a base in that location. At this time, the Ōuchi army had their main base in Tomo in the Numakuma District and Tokujumaru himself joined the deployment. Having lost an important outlying castle, the Yamana army built an outpost in the Tsubō-no-shō on Mount Ryūō located in-between Kannabe Castle and Ōmon Bay. This was known as the Tsubō fortress from which the Yamana resisted, but, on 4/28 of Tenbun 16 (1547), this fortress was also toppled. Several of the letters of commendation issued for this battle were signed by Takakage and, during this time, Tokujumaru attended his coming-of-age ceremony and the attack on Tsubō fortress was his first experience in battle.
At the same time, the main forces of the Ōuchi and Mōri aimed via a land route for Kannabe Castle. Toward the end of the twelfth month, reinforcements from the Amago approaching the provincial border were repelled by a retained of the Ōuchi named Ohara Takanobu. Sugihara Morishige, the chief retainer of the Yamana family fought valiantly, and although the conflict did not result in an attack on Kannabe Castle, in addition to the littoral region to the south (known as Sotogōri), the interior portion of Bingo to the north (known as Uchigōri) came under the control of the Ōuchi army, isolating Kannabe Castle.
All-out assault in Tenbun 17 (1548)
In the sixth month of 1548, the combined forces of the Ōuchi and the Mōri made an all-out assault on Kannabe Castle. Ōuchi Yoshitaka ordered Sue Okufusa to serve as the commander-in-chief and lead over 5,000 mounted soldiers from Suō and Nagato provinces who were joined by Mōri Motonari and over 10,000 mounted soldiers including Mōri Takamoto, Kikkawa Motoharu, Kobayakawa Takakage, Hiraga Takamune, Shishido Takaie, and Kagawa Mitsukage. Under one theory, there were over 16,000 soldiers. Meanwhile, the garrison at Kannabe Castle was comprised of only between 1,000 and 1,500 defenders.
After inheriting the headship of the Kikkawa family, this marked the first battle for Motoharu, but, on 6/23, after leading over 1,000 mounted soldiers to set fires below the castle, his forces clashed with over 300 mounted soldiers under the command of Sugihara Saemon-no-taifu. Having observed this clash, Sugihara Morishige led over 1,000 mounted soldiers to attack Motoharu’s battalion, but Motoharu’s forces fervently pushed back, charging to the fences around the castle. Having incurred injuries, Morishige withdrew with his forces.
In one account the Mōri and Yamana armies clashed on 6/2; in another account, the all-out assaults occurred on 6/18 and 6/20. With respect to battles that occurred in the sixth month, Motonari and Takamoto (father and son) issued many written commendations to their retainers. Drawing from the expressions in these sources, it appears the battles included fighting over walls and fences, but, in the end, Tadaoki endured the ferocious attacks.
In the seventh month, Ōuchi Yoshitaka instructed Ohara Takanobu and Hironaka Takakane to cut-down the rice fields as a tactic to threaten the food supply of their enemy. In addition to Ōuchi troops from Saijō in Aki, members of the Umayahara clan, a kokujin family from the interior region of Bingo, were mobilized for the effort, resulting in a comparatively large undertaking. Moreover, the instructions to the Umayahara clan were conveyed via the Mōri clan, suggesting that kokujin in the interior of Bingo were under the control of Motonari.
Assault on the castle by Hiraga Takamune
On 2/14 of Tenbun 18 (1549), Motonari, accompanied by Motoharu and Takakage, headed toward Yamaguchi. On 3/5, they met with Ōuchi Yoshitaka. Their visit to Yamaguchi continued until the fifth month, while Sue Takafusa also returned to Suō from Bingo and met with Motonari in Yamaguchi.
Meanwhile, in the second month, large battles broke-out in the foothills of the castle, and, in the fourth month, in Nanokaichi and Koyaguchi, but Tadaoki maintained his defense of Kannabe Castle. Based on advice from Hiraga Takamune who feared an extended deployment with a large army for from their home, a fortress known as Yōgaiyama Castle was built to the north of Kannabe Castle and a garrison of 800 troops from the Hiraga clan remained behind while the main forces of the Ōuchi army comprised of the Sue and Mōri withdrew. One of the reasons that Takamune entrusted them with an attack against Kannabe likely owed to resentment toward Tadaoki. During the deployment, he proposed the fourth month of 1549.
Tadaoki and Takamune engaged in a series of small-scale clashes. According to one account, one such encounter referred to as the Battle of Hiraga Sugihara commenced on 11/19 of Tenbun 18 (1549) and lasted three days, although this conflicts with other historical accounts. After visiting Yamaguchi, Motonari returned to Yoshida in Aki Province and resumed the attack against Kannabe Castle. On 7/3, Takamune died of illness while on deployment, so the remaining Hiraga forces continued attacks on the castle to avenge the loss of Takamune. Finally, on the evening of 9/4, Tadaoki abandoned Kannabe and fled, drawing to a close the contest for the castle.
After learning of the fall of Kannabe Castle, the Ōuchi clan dispatched Hironaka Takakane and Aokage Takaakira to manage the aftermath of the war. Takaakira served as a chamberlain of the castle while the littoral region in the southern portion of Bingo became a base for the Ōuchi clan. Meanwhile, the Amago clan lost a base for attacks in Bingo. The next time that the Amago clan attempted another forceful attack on Bingo occurred after the death of Ōuchi Yoshitaka in 1551 in the Tainei Temple Incident.
Yamana Tadaoki fled to Izumo Province, but, in 1553, after the Mōri severed ties with the Ōuchi and Sue clans in an event known as the Separation of Aki and Suō, Tadaoki returned to his home province in allegiance to the Mōri. Tadaoki entered Kannabe Castle as a general under the command of the Mōri. In 1556, after the death from illness of Tadaoki, upon recommendation from Kikkawa Motoharu, Sugihara Morishige, a retainer of Tadaoki, inherited Kannabe Castle.
According to one account, Takamune proposed an archery competition to bring to an end the long conflict, which was then held on 10/13 of Tenbun 19 (1550). After losing in the competition, Tadaoki turned over the castle. This story, however, conflicts with the death of Takamune on 7/4 of Tenbun 18 (1549) and the escape by Tadaoki on 9/4 of the same year.