Battle of Azukizaka

小豆坂の戦い

Oda Clan

Mikawa Province

Imagawa Clan

Years: First Battle: Tenshō 11 (1542); Second Battle: Tenshō 17 (1548)

Location:  Azukizaka in the Nukata District of western Mikawa Province

Outcome:  In the First Battle of Azukizaka, the Oda prevailed through the valiant efforts of elite fighters known as the Seven Spears of Azukizaka.  In the Second Battle of Azukizaka, the Imagawa overcame losses with an ambush that caused the Oda to collapse in disarray and alter the course of the battle in their favor.

Commanders:  [First Battle] Oda Nobuhide; [Second Battle] Oda Nobuhide, Oda Nobuhiro

Forces:  [First Battle] Unknown; [Second Battle] 4,000

Casualties:  [First Battle] Unknown; [Second Battle] Unknown

Commanders:  [First Battle] Imagawa Yoshimoto; [Second Battle] Matsudaira Hirotada, Taigen Sessai, Asahina Yasuyoshi

Forces:  [First Battle] Unknown; [Second Battle] Matsudaira: Unknown; Imagawa: 10,000

Casualties:  [First Battle] Unknown; [Second Battle] Unknown

The Battle of Azukizaka occurred over the course of two battles, the first in Tenshō 11 (1542) and the second in Tenshō 17 (1548), near Okazaki Castle in the Nukata District of Mikawa Province.  In these battles, the allied forces of the Imagawa and the Matsudaira of Mikawa defended against invasions by the Oda of Owari Province.

The unexpected killing of Matsudaira Kiyoyasu, head of the clan, at the hands of one of his retainers in an event known as the Collapse at Moriyama triggered a succession struggle in the Matsudaira.  This made the clan vulnerable to attack by powerful daimyō in neighboring provinces seeking to expand their territories.  Oda Nobuhide of Owari and Imagawa Yoshimoto of Suruga intervened with the aim of controlling the western portion of Mikawa.

Prelude to the conflict

The Matsudaira governed the Hirano District in western Mikawa, serving as lord of Okazaki Castle.  In the era of Matsudaira Kiyoyasu, almost all of Mikawa was pacified, but, in 1535, at the Collapse at Moriyama, the unexpected death of Kiyoyasu shook the clan.  Finally, Kiyoyasu’s heir, Matsudaira Hirotada, succeeded his father with the support of Imagawa Yoshimoto, the daimyō governing Suruga and Tōtōmi provinces.  Despite the succession, the clan remained unstable.

Oda Nobuhide proceeded toward becoming a sengoku daimyō by expanding his territory in southern portions of Owari.  In 1540, Nobuhide took advantage of the weakening of the Matsudaira clan by capturing Anjō Castle which served as an important base for the Matsudaira in western Mikawa.  He then expanded his domain up to the western edge of the Yanagi River which ran in front of the Matsudaira’s home base at Okazaki Castle.

The First Battle of Azukizaka

While Oda Nobuhide advanced toward the Hirano District in western Mikawa, Imagawa Yoshimoto backed the Matsudaira while expanding his control from eastern Mikawa to western Mikawa.  In an effort to repel the Oda forces from western Mikawa, in the eighth month of 1542 (or, under one theory, the twelfth), Yoshimoto led a large army to Ikutahara.  Nobuhide responded by departing from Anjō Castle, crossed the Yanagi River, and set-up an encampment on the opposite bank in Uewada.  On 8/10, the armies engaged in a violent clash to the southeast of Okazaki Castle at Azukizaka.

This battle ended in victory for the Oda in part owing to the valiant fighting of senior commanders including a group known as the Seven Spears of Azukizaka.  This decorated group featured Oda Nobumitsu, Oda Nobufusa, Okada Shigeyoshi, Sassa Masatsugu, Sassa Magosuke, Nakano Kazuyasu, and Shimokata Sadakiyo.  Taigen Sessai served as a commander for the Imagawa.

The Second Battle of Azukizaka

After the initial clash at Azukizaka, the Oda acquired more influence in the border area between Owari and Mikawa.  In 1544, Mizuno Nobumoto, from a local family based at Kariya Castle in the Hekikai District, exercised influence in this border area.  Although Nobumoto was the older brother of Odai-no-kata, the wife of Matsudaira Hirotada who ruled as the lord of Okazaki Castle, he severed ties with the Matsudaira, separated himself from the Imagawa, and pledged allegiance to the Oda.

These developments caused Hirotada to resist the Oda while forging closer ties with the Imagawa.  Hirotada validated the relationship with the Imagawa by sending his lineal son, Takechiyo (later known as Tokugawa Ieyasu) as a hostage to the home base of the Imagawa in Sunpu.  However, in 1547, owing to a betrayal by Toda Yasumitsu (lord of Tahara Castle) who was responsible for transporting the six-year-old Takechiyo to the Imagawa, Takechiyo was transferred to the Oda instead.  Oda Nobuhide endeavored to utilize Takechiyo as a hostage to persuade Hirotada to abandon the Imagawa and submit to the governance of the Oda.  Instead, however, Hirotada relied upon the Imagawa to pledge resistance to the Oda at all costs.

Around this time, Nobuhide had his eldest son, Oda Nobunaga, wed Nōhime, the daughter of Saitō Dōsan, promoting reconciliation with their long-time rivals from Mino Province.  This removed the threat of attack from the north, allowing Nobuhide to turn his attention  to the east where he used Anjō Castle as a beachhead to plan for an attack against the Matsudaira at Okazaki Castle.

In the third month of 1548, while Nobuhide aimed to attack Okazaki with his forces, his eldest illegitimate son, Oda Nobuhiro, led a vanguard of 4,000 soldiers from Anjō Castle, crossing the Yanagi River and establishing a base in Uewada.  Meanwhile, in support of the Matsudaira, Imagawa Yoshimoto deployed 10,000 soldiers led by Taigen Sessai as the lead commander and Asahina Yasuyoshi as the second in command.  On 3/19, these forces clashed with the vanguard of the Oda led by Nobuhiro at Azukizaka.

In this battle, the Imagawa forces held an initial advantage owing to the location of their base on top of a hill.  Aware of the disadvantage, Nobuhiro led his men down to the base of Nobuhide’s main contingent at Tōboku.  After converging with the main forces, the Oda regained their zeal and overwhelmed the Matsudaira in fierce combat, while the Imagawa gradually faced the prospect of defeat.  Then, a unit of the Imagawa who had been lying in ambush launched an attack that changed the course of the conflict, sending the Oda forces into disarray, causing them to cross the Yanagi River again, and flee to Anjō Castle in defeat.

Until this time, the alignment by Matsudaira Hirotada at Okazaki Castle with the Imagawa served as a known premise for the Second Battle of Azukizaka.  However, according to the writings of Nichikaku, the ninth-generation priest of the Honjō Temple in Echigo Province (originally of Owari Province and a convert from the Udono clan who were retainers of the Imagawa), the Oda army toppled Okazaki Castle in the autumn of 1547.  There is support among some scholars for this event, as well as the possibility that Takechiyo was not transferred to the Oda as a result of betrayal, but rather by Hirotada himself as proof of surrender to the Oda.

Theories that, in the Second Battle of Azukizaka, Okazaki Castle and Matsudaira Hirotada were allied with the Oda

If Hirotada and Okazaki Castle had surrendered to the Oda one-half year prior to the Second Battle of Azukizaka, the timing of Hirotada’s alignment with the Oda has a major effect on the interpretation of the battle.  Hirotada and Okazaki Castle may have allied with the Imagawa at the time of the Battle of Tokabara toward the end of the ninth month of 1547.  However, at the time of the Second Battle of Azukizaka, there is also strong possibility that Hirotada and Okazaki Castle were allied with the Oda, and after the victory by the Imagawa, realigned with the Imagawa.  Reasons for this view include accounts that (i) the forces from Okazaki were led by Asahina Nobuoki, a retainer of the Imagawa, (ii) when the forces from Okazaki deployed from the castle and converged withe the Imagawa army coming from the east, the Oda forces crossing the Yanagi River from the west sought to capture Okazaki Castle in their absence, (iii) even if Hirotada’s unit remained in Okazaki Castle, there is a conspicuous absence of accounts of attacks or pursuits of the Oda army during the retreat by the Oda across the Yanagi River that ran from Azukizaka alongside Okazaki Castle, and (iv) based on the foregoing, if Hirotada and the forces from Okazaki were allied with the Imagawa, they may have been secretly colluding with the Oda.  In that case, it is likely that, in the Second Battle of Azukizaka, Hirotada and the forces from Okazaki were allied with the Oda and switched to the Imagawa after the victory by the Imagawa.  Meanwhile, the forces from Okazaki may not have been able to accept the prospect of surrender to the Oda, and instead served as mercenaries of the Matsudaira with support of the Imagawa.  Based on this theory, some of the Matsudaira retainers followed Hirotada by surrendering to the Oda while others may have refused and joined the Imagawa instead.

Among those who believe Hirotada and Okazaki Castle surrendered to the Oda, there is a view that, at the time of the Battle of Azukizaka, Hirotada had already allied again with the Imagawa.  For example, in 1548, at the urging of Saitō Dōsan, Oda Yamato-no-kami and Hirotada raised arms.  The Battle of Azukizaka may have occurred as a result of Hirotada’s realignment with the Imagawa.  Based on this theory, Saitō Dōsan and Hirotada were allied and the machinations of Dōsan were one of the causes for the Second Battle of Azukizaka.

The Oda and Imagawa after the Battle of Azukizaka 

In 1548, the allied forces of the Imagawa and Matsudaira achieved victory at the Second Battle of Azukizaka, but Hirotada died later that year.  His successor was Takechiyo, who was a hostage of the Oda clan, leaving Okazaki Castle without a lord.  In 1549, Taigen Sessai plotted to bring Takechiyo back under the protection of the Imagawa through a hostage exchange.  During 11/8 and 11/9 of 1549, he led allied forces from the Imagawa and Matsudaira armies to attack Anjō Castle, captured Oda Nobuhiro as their prisoner, and succeeded in exchanging him for Takechiyo.  The Imagawa brought Takechiyo to Sunpu and placed him securely under the protection of the Matsudaira, while stationing a representative of the Imagawa at Okazaki Castle in western Mikawa.  Meanwhile, owing to the fall of Anjō Castle, the incursion by the Oda forces into MIkawa ended in failure.  On 3/3 of 1552, Oda Nobuhide died of illness, giving rise to a succession struggle between his eldest son, Oda Nobunaga, and Nobunaga’s younger brother, Oda Nobukatsu (also referred to as Oda Nobuyuki).  This destablized the presence of the Oda in the border area between Owari and Mikawa provinces.  Around the time of Nobuhide’s death, the Yamaguchi clan who controlled Narumi and Kasadera castles in Owari surrendered to the Imagawa.  Rather than the Oda making headway in Mikawa, the Imagawa began to encroach in the Oda province of Owari.

Nobunaga ultimately prevailed in the conflict against Nobukatsu, proceeded to unify Owari, and re-captured Kasadera Castle from the Imagawa.  He then built fortresses near Narumi Castle, laying seige to the castle defended by Okabe Motonobu who was allied with the Imagawa.  Next, in 1560, Imagawa Yoshimoto, the powerful sengoku daimyō from Suruga Province led a large army on an invasion of Owari.  Beginning with Narumi Castle, these forces provided support to isolated units of the Imagawa and endeavored to reverse their losses in the border area.  These actions led to the Battle of Okehazama and subsequent loss of Yoshimoto, whereupon the Imagawa army quickly retreated from Mikawa, creating an opportunity for the Matsudaira clan under Matsudaira Motoyasu (later known as Tokugawa Ieyasu) to regain control.  Before long, the Matsudaira allied with the Oda in an arrangement known as the Kiyosu Alliance, drawing to an end a long period of conflict on the border between Mikawa and Owari.