Siege of Iwaya Castle
Date: Seventh month of Tenshō 14 (1586)
Location: Iwaya Castle in the Mikasa District of Chikuzen Province
Outcome: The Shimazu army finally prevailed in a ferocious fight to the end during which Takahashi Jōun rejected multiple offers of surrender in a battle that claimed the lives of all castle defenders and many attacking forces.
The Siege of Iwaya Castle occurred in the seventh month of Tenshō 14 (1586). In this conflict, the Shimazu clan of Satsuma Province who aimed for a hegemony in Kyūshū toppled Iwaya Castle defended by Takahashi Jōun, a retainer of the Ōtomo clan. The siege led to a ferocious battle to take the castle with large numbers of soldiers killed in action.
Prelude to the battle
In 1584, at the Battle of Okitanawate, the Shimazu killed Ryūzōji Takanobu. After the loss of their mainstay, the Ryūzōji clan capitulated to the Shimazu, which in turn enabled the Shimazu to rapidly gain power. In this same year, lesser powers such as Kumabe Chikanaga and Kumabe Chikayasu (father and son) of Higo, Akizuki Tanezane of Chikuzen, and Tsukushi Hirokado of eastern Hizen strengthened their relations with the Shimazu either by yielding their allegiance or through peace arrangements. This provided a means for these clans to respond to an unstable environment including separation from the Ryūzōji clan and potential confrontations with the Ōtomo clan. The next year, after Aso Koremitsu of Higo surrendered to the Shimazu, the Ōtomo were the only obstacle remaining between the Shimazu and their deep aspiration to gain control of all of Kyūshū.
Shimazu Yoshihisa, the sixteenth head of the Shimazu clan (in addition to being the shugo daimyō of Satsuma and a sengoku daimyō), ordered the army to advance into Chikuzen. Shimazu Tadanaga and Ijūin Tadamune served as commanding generals for a deployment of over 20,000 soldiers. Just before the march, Tsukushi Hirokado (who had switched his allegiance to the Ōtomo) surrendered at Katsu-no-o Castle. The only ones continuing to resist the Shimazu in Chikuzen were under the command of the Ōtomo, including: (i) Takahashi Jōun of Iwaya Castle, (ii) Takahashi Munemasu (the second son of Jōun and lord of Hōmanzan Castle, later known as Tachibana Naotsugu), and (iii) Tachibana Muneshige, the eldest son of Jōun and lord of Tachibanayama Castle.
Course of events
A total of 763 soldiers were positioned in Iwaya Castle. On 7/12 of 1586, the Shimazu army issued a demand for surrender, but Jōun did not accept it and instead committed to a fight to the end. On 7/14, the Shimazu forces commenced attacks on the castle. However, a majority of the Shimazu army hailed from other provinces and lacked an esprit de corps. Under the command of Jōun, the Shimazu army was repeatedly repelled and lost a frightening number of soldiers. Struggling in their attack against the castle, the Shimazu offered a settlement if Jōun would send his son to them, but, once again, Jōun refused. A stalemate ensued for several weeks until, on 7/27, Shimazu Tadanaga himself commanded an all-out attack on the castle. After incurring numerous casualties, the attacking forces penetrated the defenses and, finally, only an inner citadel remained where Jōun was holed up. Jōun proceeded to climb a tall watchtower and committed seppuku. All of the other defenders died fighting, whereupon the battle came to a dramatic end.
Meanwhile, the Shimazu lost many of their own soldiers in the attack on Iwaya and it required a period of time to reconstitute their army. This was an underlying reason for the inability to later achieve their aspiration of a hegemony in Kyūshū.
Aftermath of the battle
The commitment to fight to the end under Jōun’s command resulted in an honorable death in battle. However, the Shimazu army also incurred serious losses so attacks against Tachibana Muneshige, who was holed up at Tachibanayama Castle, stalled. While the Shimazu spent time attacking Tachibanayama Castle, a Toyotomi army of 200,000 soldiers landed in Kyūshū. This compelled the Shimazu army to retreat to their home province of Satsuma in southern Kyūshū. Resistance in exchange for Jōun’s life ultimately prevented the Shimazu army from conquering all of Kyūshū.
Jōun deliberately entered Iwaya Castle in anticipation of an offensive by the Shimazu forces. As the commander-in-chief, Jōun took this action in a bid to prevent the Shimazu forces from circumventing him and attacking Tachibana Castle. Jōun’s son, Tachibana Muneshige, was based in Tachibana Castle. Meanwhile, Jōun’s wife and his second son, Takahashi Munemasu, took refuge along with other women and children in Hōmanzan Castle. Until the arrival of the Toyotomi army to support them, Jōun set himself up as a decoy and committed to a fight to the end. All of the defenders at Iwaya died an honorable death, but the Shimazu also incurred serious losses, so had to temporarily retreat to reconstitute their forces. As a result, Jōun’s lord (the Ōtomo family) and his eldest son, Tachibana Muneshige, were able to hold out until the arrival of support from the Toyotomi army. Jōun’s second son, Takahashi Munemasu, was captured as a prisoner of war through the devices of the Shimazu but was later released.
Jōun’s eldest son, Tachibana Muneshige, who was adopted by the Tachibana clan, informed his retainers that he wanted to send reinforcements to Iwaya Castle where his father was holed-up. Owing to his origin as an adoptee from another family, he did not expect the retainers to step forward, but Yoshida Kanemasa (Yoshida Sakyō) and many others indicated their willingness to go. Sakyō stated that the path of bushi is based on honor, whereupon he led a unit of over twenty reinforcements to Iwaya Castle who were killed in the battle. Thereafter, the surviving members of their families were treated generously by Muneshige.
The commanders in the Shimazu army respected the battle skills of the bushō under the command of Jōun, and sent offers for surrender multiple times. Jōun, however, declared in the presence of allies and enemies alike that many others pledge loyalty when their lords are thriving and betray them when their lords are struggling, but he could not forget his deep gratitude and betray his lord. Those who forget gratitude are lower than animals. All who heard him expressed agreement with his sentiment. In this connection, Jōun received five offers for surrender – three from the Shimazu and one each from allies Tachibana Muneshige and Kuroda Yoshitaka, who each told him they could not support the defense of Iwaya Castle so he should retreat. In each instance, he politely received the messenger and informed him that he refused the offer.
After the fall of the castle, Shimazu Tadanaga (the commanding general), along with other commanders of the Shimazu army, displayed Takahashi Jōun’s head for the ritual post-battle inspection. At this event, Tadanaga said that his army had killed many outstanding warriors in the battle, and that if he had been friends with Jōun, they would have been the best of friends, after which he departed from the table and those in attendance were left in tears.