Battle of Hitotoribashi
Date: 11/17 of Tenshō 13 (1586)
Location: Near the Hitotori Bridge across the Seto River (a tributary of the Abukuma River) in the Adachi District of Mutsu Province
Outcome: Outnumbered by more than 4 to 1, the Date army was on the defensive throughout the battle, but after Masamune escaped to Motomiya Castle, the Satake and their allied forces disbanded to address threats in Hitachi Province posed by the Hōjō clan.
The Battle of Hitotoribashi occurred on 11/17 of Tenshō 13 (1586) near Hitotoribashi (the Hitotori Bridge) in Motomiya in the Adachi District of Mutsu Province. Waged between the Date clan and an allied army led by the Satake, the conflict was triggered by the abduction of Date Terumune (a sengoku daimyō and sixteenth head of the Date clan) by Nihonmatsu Yoshitsugu (also known as Hatakeyama Yoshitsugu), the lord of Nihonmatsu Castle, that resulted in the death of both men as well as those accompanying Yoshitsugu.
In this period, the Date clan maneuvered to consolidate the power of groups of relatives comparable to sengoku daimyō referred to as utsuro in the southern portion of Mutsu. Following the untimely death of Terumune, the clan backed his eldest son, Date Masamune, in battle to avenge the loss by attacking Nihonmatsu Castle. In the course of this battle, the Date violently clashed with forces sent by daimyō families from the southern region led by the Satake and Ashina clans who came under the pretext of supporting the Nihonmatsu.
The Battle of Hitotoribashi arose from an opportunity by the utsuro of the Satake, the Iwaki, the Nikaidō, the Ashina, the Shirakawa-Yūki, and the Ishikawa clans to supplant the Date clan owing to a series of important developments in the Azuchi-Momoyama period affecting the balance of power in Mutsu. These events included (i) a collapse of the Muromachi bakufu in 1573 that resulted in a loss of authority for their appointed representative in Mutsu, known as the Ōshū tandai, (ii) the death in 1578 of Date Harumune (a sengoku daimyō and fifteenth head of the Date clan), (iii) a succession struggle within the Ashina family after the death in 1584 of Ashina Moritaka (a sengoku daimyō and eighteenth head of the Ashina clan) that led to a successor backed by the Satake clan, (iv) the breaking of an alliance by Date Masamune with the Ashina followed by a failed attack in the fifth month of 1585 known as the Battle of Sekishiba, (v) restoration of the authority of the Imperial Court following the appointment of Hashiba Hideyoshi as the Chief Advisor to the Emperor, or kanpaku, (vi) a change in the generation of leadership in the Date clan following the sudden death of Terumune (the second son of Harumune), and (vii) a prolonged standoff during which the Nihonmatsu-Hatakeyama clan holed up in their castle without yielding to the siege.
On 6/2 of Tenshō 10 (1582), Oda Nobunaga died in a dramatic coup d’état launched by one of his most senior retainers, Akechi Mitsuhide, in an event known as the Honnō Temple Incident. This ended the bid by Nobunaga to establish a countrywide hegemony. During this period, Date Terumune sought to consolidate the authority of utsuro in the southern portion of Mutsu, attacked Sōma Moritane and his son, Sōma Yoshitane, and recovered the Igu District where his grandfather, Date Tanemune, had earlier retired.
On 10/6 of 1584, the death of Ashina Moritaka, the head of the Ashina clan, raised the specter of a succession struggle. At this time, a deepening confrontation ensued between Ōuchi Sadatsuna, the lord of Obama Castle in the Shiomatsu territory and the Tamura clan who were the birth family of Masamune’s formal wife, Megohime. The Shiomatsu territory served as a buffer zone surrounded by the territory of the Date on one side and the Nihonmatsu, the Tamura, and the Sōma on the other. That same month, after taking over control of the clan from his father (Terumune), Date Masamune pressured Sadatsuna to submit to the Date family. Sadatsuna refused to subordinate himself and, instead, rebelled with the support of the Ashina family.
In the fifth month of 1585, Masamune attacked the Ashina clan and suffered a loss. Several months later, Hashiba Hideyoshi was appointed as the kanpaku and adopted the Toyotomi surname. Masamune then invaded the Shiomatsu territory of Ōuchi Sadatsuna, causing Sadatsuna to flee to the territory of the Nihonmatsu and the Ashina. Masamune proceeded to attack Nihonmatsu Yoshitsugu, the lord of Nihonmatsu Castle, who had marital ties to the family of Sadatsuna. Yoshitsugu surrendered through the offices of Terumune.
On 10/8, Yoshitsugu abducted Terumune during a meeting at Miyamori Castle, whereupon he was killed along with Terumune by forces led by Masamune in pursuit of the abductors. On the preceding day, a messenger came to inform Yoshitsugu’s son, Kuniōmaru, that his father would return that day, so he departed to meet his father en route, but as he neared the Abukuma River, he was surprised to hear gunfire from an approaching army. The Nihonmatsu clan, led by Yoshitsugu’s younger cousin, Araki Moritsugu, backed Kuniōmaru, which escalated into a hold-out in the castle. Notifications were given by urgent messenger to Satake and Aizu, and those stationed at the auxiliary castles of Motomiya, Tama-no-i, and Shibukawa vacated those sites to gather at Nihonmatsu.
On 10/15, after the memorial service for Terumune, Sōma Yoshitane consented to a request from Masamune to join a battle, along with Tamura Kiyoaki (the father of Masamune’s formal wife), to avenge the loss of Masamune’s father. Together, they led an army of 13,000 soldiers to commence an attack against Nihonmatsu Castle. On 11/2, to support the Nihonmatsu clan, an array of daimyō from southern Mutsu (including Satake Yoshishige, Satake Yoshinobu, Ashina Kameōmaru, Nikaidō Onami, Iwaki Tsunetaka, Ishikawa Akimitsu, Shirakawa Yoshimi, and Shirakawa Yoshihiro) dispatched forces. On 11/10, these allied forces then advanced to the Suka River. At this time, Sasagawa, Hidenoyama, Koarata, and Kōriyama were controlled by the Tamura clan while Satake Yoshinobu established a base at Kubota Castle. Sōma Yoshitane, who participated in the attack on Nihonmatsu Castle to assist Masamune, heard rumors of betrayal by the Ishikawa, Shirokawa, and Suda Hōki which prompted him to return to the base. Meanwhile, Tamura Kiyoaki set-up a position near the Gyōgō Temple to the southeast of Akutsu where his retainer named Ukon Daibu resided.
Upon learning that the allied army was approaching, Masamune left in place the forces laying siege to Nihonmatsu Castle and reinforced the defenses at castles under his control, and then, to interdict the enemy forces, led the main contingent of 7,000 soldiers to Iwatsuno Castle and then to Motomiya Castle.
Course of events
After departing Motomiya Castle, Masamune traversed the Adatara River and set-up a base to the south at the Mount Kannondō. On the prior day, the allied army of the Satake and daimyō from southern Mutsu camped at Maedasawa to the south of the Gohyaku River and then marched north toward the main base of the Date. The armies violently clashed near the Hitotori Bridge that spanned the Seto River (a tributary of the Abukuma River). The allied forces outnumbered the Date forces by a ratio of more than four to one (30,000 versus 7,000 men). Consequently, the allied forces were on the offensive from beginning until end. The Date army suffered a rout, while the allied forces thrust forward into the main base of the Date. Masumune himself was shot in his armor by one arrow and five bullets. With defeat imminent, the Date army made efforts to enable Masamune to retreat. A veteran commander named Oniniwa Yoshinao, with the gourd-shaped war fan in hand, served as the rear guard, crossing the Hitotori Bridge to plunge into the enemy formation and be struck down.
Meanwhile, located to the east at a residence on the Seto River, a contingent of 500 men led by Data Shigezane incurred a pincer attack but were able to hold their ground long enough for Masamune to escape to Motomiya Castle. The Date army suffered major losses but with the sunset, the battle came to end. Nevertheless, that night, a commander of the Satake named Onosaki Yoshimasa (the son of Satake Yoshiatsu – the eighteenth head of the Satake clan) was stabbed to death by his retainers at the camp. Further, news came that Edo Shigemichi (lord of Baba Castle) and Satomi Yoshiyori of Awa Province who were allied with the Hōjō clan were coming to invade their domain in Hitachi Province so decisions were made for the Satake army to retreat. Given the numerical superiority of the Satake army, the sudden retreat caused speculation years later as to whether tactics by Masamune had any role in the outcome.
Aftermath of the battle
From the perspective of political maneuvers and military tactics, the allied forces were victorious to the extent they liberated the daimyō of southern Mutsu from governance by the Date of the family groups referred to as utsuro. However, at the Battle of Miyoda that occurred five years before (similar to the Battle of Hitotoribashi, a battle in which allied forces led by the Satake clan defeated the Tamura clan who supported the Date), there is a theory that leadership of the daimyō of southern Mutsu transferred from the Date to the Satake. Therefore, this battle may have only preserved the role of the Satake utsuro that was already in place.
With respect to military strategy, notably, the allied forces prevented the fall of Nihonmatsu Castle, and significantly harmed the Date army. Nevertheless, the allied forces did not attack Motomiya Castle or annihilate the Date army so the battle did not result in a decisive outcome.
Masamune went from Iwatsuno Castle to Obama Castle and resided there during the winter. The following spring, Masamune arranged for another attack on Nihonmatsu Castle, but could not penetrate owing to the defenses of Araki Moritsugu, as well as attacks from behind by forces associated with the daimyō of southern Mutsu. The Nihonmatsu forces holed up in the castle had also reached their limit for continued fighting, so, in the summer, through the offices of Sōma Yoshitane, a settlement was reached on the condition that the Nihonmatsu forces be allowed to retreat to Aizu. This allowed for Nihonmatsu Castle to be vacated without further bloodletting. This resulted in a written claim from retainers of the Ashina family to Satake Yoshishige.
After this battle, the conflict between the Satake and Hōjō clans intensified, thereby preventing the Satake from mounting another military action against the Date. Although Date Shigezane became the next lord of Nihonmatsu Castle, the utsuro established by Date Tanemune and Date Harumune disintegrated, and leadership of the political system and diplomatic order in southern Ōu (Mutsu and Dewa provinces) previously maintained by the Date was taken away by the allied forces led by the Satake clan. Aiming to shed outdated structures of governance and to establish a hegemony in Ōu, Date Masamune utilized Nihonmatsu Castle as a foothold to further expand his territory and advance through military force into the Ashina domain.