Battle of Katakaku-ikusagaya
Date: Eishō 6 (1509)
Location: The area of Katakaku-ikusagaya in Shimotsuke Province
Outcome: Naganuma Masayoshi joined forces with Ashina Moritaka in bid to expand their territory from Mutsu into Shimotsuke Province, but were repelled by Utsunomiya Shigetsuna.
The Battle of Katakaku-ikusagaya occurred in 1509 in Shimotsuke Province. The clash was triggered when the combined forces of the Ōushū-Naganuma and Ashina clans from Mutsu were intercepted by the Utsunomiya army in Shimotsuke. It is also known as the Battle of Katakakuhara.
Naganuma Masayoshi, the lord of Shigiyama Castle in Aizu in Mutsu Province, presided over the era of peak prosperity of the Ōushū-Naganuma clan. Masayoshi sought to reclaim the former territory of the notable Naganuma military family in Shimotsuke Province, whereupon he betrayed his lord, Ashina Moritaka (the sengoku daimyō of Aizu), and the Utsunomiya clan. With the assistance of the Sekiya clan (retainers of the Shionoya family) who colluded with him, Masayoshi invaded Katakaku-ikusagaya in Shimotsuke. In response, Utsunomiya Shigetsuna, the sengoku daimyō of Shimotsuke, intercepted and repelled the combined forces of the Ashina and Ōushū Naganuma.
Prelude to hostilities
In 1495, a plot by Matsumoto Suketoyo and Itō Minbu to rebel against Ashina Moritaka was quickly discovered and suppressed. Thereafter, Suketoyo and others fled toward Shimotsuke Province through the assistance of Utsunomiya Shigetsuna. In these circumstances, Naganuma Masayoshi captured and killed as many as thirty of the men attempting to flee, demonstrating his cooperation with Moritaka. Later that year, Masayoshi invaded Shiobara in Shimotsuke, attacking Yōgaiyama Castle defended by Tachibana Ise-no-kami, a member of the Shiotsuke-Oyama clan. Ise-no-kami fought to the end from the auxiliary base of Sama Castle, but was killed in action and the Tachibana clan eliminated. The Shiobara manor was previously governed by Naganuma Munemasa, the founder of the Naganuma clan and former territory of the Naganuma clan. Masayoshi succeeded in recovering this former territory of the clan.
After capturing Yōgaiyama Castle, Masayoshi received reinforcements from Ashina Moritaka and his own territory of Aizu-Tajima to oppose a northward push by Utsunomiya Shigetsuna. At the Battle of Miyori, a village in the north of Shimotsuke, Masayoshi succeeded in repelling the Utsunomiya forces. He then took further steps to resist Shigetsuna including a major reconstruction of Yōgaiyama Castle. As the the Ōushū-Naganuma witnessed the peak of their prosperity, the clan controlled the territory from southern Mutsu Province to the border area with Shimotsuke. Meanwhile, Ashina Moritaka is considered to have cooperated with the Ōushū-Naganuma out of a desire to advance into Shimotsuke.
Course of events
In 1509, Naganuma Masayoshi led an allied army that included Ashina forces under Ashina Moritaka to invade Katakaku-ikusagaya in the territory of the Shionoya clan. On this occasion, the Sekiya clan (retainers of the Shionoya) who colluded with Masayoshi was deeply involved in the invasion. Utsunomiya forces led by Utsunomiya Shigetsuna intercepted them. Shigetsuna became aware of the betrayal of the Sekiya clan and attacked. As a result, the combined forces of the Ashina and Naganuma collapsed and the Utsunomiya achieved an overwhelming victory. Masayoshi then quit Shiobara in the Nasu District of Shimotsuke and retreated to Aizu-Tajima. Having captured Yōgaiyama Castle, Shigetsuna appointed Shionoya Tsunamune of the Shionoya clan to serve as the lord of the castle.
At the Battle of Katakaku-ikusagaya, the loss by the combined forces of Naganuma Masayoshi and Ashina Moritaka marked a significant setback in the sphere of influence of the Ōushū-Naganuma clan during their attempted expansion into Shimotsuke Province. This led to a final settlement of the conflict between the Ashina and the Ōushū-Naganuma clans. Thereafter, Yōgaiyama Castle served as a base for Ōushū forces allied with the Utsunomiya until the Shimotsuke-Utsunomiya clan was demoted on 10/13 of 1597 by Toyotomi Hideyoshi.