Siege of Ishino Castle
Date: Seventh and ninth months of Tenshō 6 (1578)
Location: Niiro-Ishino Castle in the northern portion of Hyūga Province
Synopsis: As a prelude to battle against the Ōtomo army of Bungo Province, Shimazu Yoshihisa aimed to topple Ishino Castle in northern Hyūga Province, defended by retainers of the Itō clan. On their first attempt, the Shimazu army suffered a harrowing defeat, failing to capture the stronghold. Two months later, the Shimazu army launched a second assault, and, in the course of an extended battle, the provisions in the castle ran low, forcing the defenders to vacate the castle.
Lord: Shimazu Yoshihisa
Commanders: Shimazu Tadanaga, Shimazu Mochihisa, Ijūin Tadamune
Forces: 7,000 (first battle); 10,000 (second battle)
Losses: Over 500 (first battle), unknown (second battle)
The Siege of Ishino Castle occurred on two occasions, in the seventh and ninth months of Tenshō 6 (1578). In this conflict, the Shimazu clan of Satsuma Province attacked a band of retainers of the Itō clan at Niiro-Ishino Castle in Hyūga Province after the Itō had temporarily withdrawn from Hyūga. These were preliminary clashes to the Battle of Mimikawa waged between the Shimazu clan and the Ōtomo clan of Bungo Province.
Niiro-Ishino Castle was located in Ishikawauchi in the central portion of Hyūga. Niiro-Ishino was counted among the Forty-Eight Castles of the Itō – outlying castles and fortresses under the control of the Hyūga-Itō clan during their period of peak prosperity (particularly the Eiroku era (1558 to 1570) under Itō Yoshisuke and his successor, Itō Yoshimasu. Around 1568, Nagatomo Genjirō served as the lord of the castle. In 1572, in the wake of the Battle of Kizakibaru, the Itō clan began to fall into decline. By 1577, the Itō could no longer resist an invasion by the Shimazu clan and, through the assistance of Ōtomo Sōrin (a sengoku daimyō and the twenty-first head of the Ōtomo clan), the Itō and their retainers temporarily withdrew from Hyūga to Bungo in northern Kyūshū. By this means, Shimazu Yoshihisa garnered control of a majority of Hyūga so that a showdown with Sōrin who governed northern Kyūshū became inevitable.
Meanwhile, after receiving Yoshisuke in Bungo, Sōrin responded to Yoshisuke’s appeals to deploy troops to Hyūga. First, in the second month of 1578, he sent vanguard forces of the Ōtomo army to Kadogawa in the northern portion of Hyūga. On this occasion, the Itō band of retainers followed orders from Yoshisuke to accompany them and, in the third month, retainers including Nagakura Sukemasa and Yamada Munemasa entered Ishino Castle in northern Hyūga and made preparations to resist an anticipated invasion by the Shimazu army from northern Hyūga to Bungo.
Battle in the seventh month
In the sixth month, upon orders of Itō Yoshisuke, Ishino Castle was rebuilt while Nagakura Sukemasa and Yamada Munemasa were appointed to defend the castle, commanding a garrison of 600 soldiers from the Itō band of retainers to prepare defenses against the Shimazu army. Upon learning of these developments, Shimazu Yoshihisa aimed to topple Ishino Castle before engaging the Ōtomo army in battle, whereupon he dispatched an army of 7,000 soldiers under the command of Shimazu Tadanaga, Shimazu Mochihisa, and Ijūin Tadamune.
On 7/6, the Shimazu army arrived at Ishino Castle to begin their assault, but it was a natural stronghold surrounded by a fast-flowing river on three sides and a steep mountain behind, making the attack exceedingly difficult for the Shimazu army. Owing to stiff resistance by the Itō forces defending the castle under the command of Sukemasa and Munemasa, the Shimazu army incurred over 500 casualties. Kawakami Norihisa (a vice general) was killed in action while Shimazu Tadanaga sustained serious injuries when his left thigh was pierced by an arrow. After being repulsed and incurring significant losses, Ijūin Tadamune met with other commanders of the Shimazu army and decided to retreat to Sadowara, abandoning their plan to capture the castle.
The outcome of this battle soon became known across Bungo. Members of the Itō band of retainers, including Nagakura Sukemasa and Yamada Munemasa, received certificates of commendation from Ōtomo Yoshimune, but the Itō were unable to obtain a large reinforcement army from the Ōtomo.
Battle in the ninth month
Two months after suffering a defeat and failing to capture the castle, on 9/15, the Shimazu army launched a second assault against Ishino Castle. On this occasion, Shimazu Mochihisa served as the commander-in-chief, along with Shimazu Tadanaga, Ijūin Tadamune, Hirata Mitsumune, and Uwai Kakuken as vice-generals, leading an army of over 10,000 soldiers. To traverse the river, the Shimazu army cut-down trees to construct a floating bridge, proceeding to attack day and night with an arsenal of bow and arrows as well as arquebuses. Nevertheless, the garrison of the Itō army defending the castle firmly resisted the assault. Violent clashes ensued for over ten days, after which the provisions in the castle began to run low. Meanwhile, there was no prospect of reinforcements coming to the aid of the defenders, so, on 9/29, Nagakura Sukemasa and Yamada Munemasa finally vacated the castle and the Itō army withdrew toward Kadogawa.
One-half year after the end of resistance in Ishino, many members of the Itō band of retainers continued to reside and amass in Hyūga, converging with the Ōtomo army to maintain their violent opposition to the Shimazu army. In particular, Nagakura Sukemasa, in collusion with the Ōtomo, independently raised arms, threatening and repulsing the Shimazu army from behind. In 1578, the Ōtomo were defeated at the Battle of Mimikawa, resulting in the death of retainers of the Itō who had converged with the Ōtomo, in addition to retainers of the Ōtomo. Surviving retainers of the Itō joined the Ōtomo army by temporarily retreating from Hyūga to the home province of the Ōtomo in Bungo.
In 1918, a novelist and artist known as Musha-no-kōji Saneatsu founded a general incorporated association referred to as Hyūga-Atarshiki-Mura, a type of utopian village located on the vestiges of Ishino Castle in Kijō in the Koyu District of Miyazaki Prefecture.