Battle of Numajiri
Date: Fifth to eighth months of Tenshō 12 (1584)
Location: Numajiri and Iwafuneyama in Shimotsuke Province
Synopsis: The expansion of power by the Gohōjō clan across northern Kantō posed a threat to regional daimyō, including the Satake clan of Kōzuke and the Utsunomiya clan of Shimotsuke. Joining with the Sano, the Yūki, and others, a coalition of 3,000 soldiers established a base in Numajiri to confront a contingent from the Gohōjō. Toward the end of a prolonged deployment, the Gohōjō gained the upper hand in battle on Mount Iwafune, providing momentum for a settlement.
Lord: Satake Yoshishige, Utsunomiya Kunitsuna
Commanders: Satake Yoshishige, Utsunomiya Kunitsuna, Yūki Harutomo, Sano Munetsuna, Yura Kunishige, Nagao Akinaga, Tagaya Shigetsune
Forces: 3,000 (or, according to other sources, 20,000 to 30,000)
The Battle of Numajiri occurred from the fifth to eighth months of Tenshō 12 (1584) in Numajiri and Iwafuneyama in Shimotsuke Province. The conflict was waged between the Gohōjō army and the allied forces of the Satake and Utsunomiya clans and is notable for the preparation of 8,000 arquebuses by the allied army in the northern Kantō – an unprecedented quantity of this newer weapon for a single conflict. This significantly exceeded the 3,000 arquebuses supplied for the Battle of Nagashino between the allied forces of the Oda and Tokugawa against the Takeda army in 1575.
On 6/2 of Tenshō 10 (1582), Oda Nobunaga died in a coup d’état orchestrated by Akechi Mitsuhide in an event known as the Honnō Temple Incident. Soon thereafter, in the sixth month of 1582, the Gohōjō clan defeated Takigawa Kazumasu at the Battle of Kannagawa, expanding their authority from Kōzuke to Shinano. Next, at the Tenshō Jingo Conflict, the Hōjō settled with Tokugawa Ieyasu and withdrew from Shinano. Meanwhile, the conditions of settlement permitted the Hōjō to take over Kōzuke. In 1583, Hōjō Ujinao had Hōjō Takahiro attack Mayabashi in the Gunma District and, with the exception of the territory of Sanada Masayuki in the northern portion, seized control of almost all of Kōzuke Province.
These developments caused alarm among various landlords in the northern Kantō including Satake Yoshishige and Utsunomiya Kunitsuna. Sano Munetsuna is surmised to have persuaded Yura Kunishige and Nagao Akinaga (siblings) to abandon the Hōjō and, on 11/27 of Tenshō 11 (1583), they attacked an ally of the Hōjō, Tomioka Hidetaka, at Koizumi Castle. On 2/24 of Tenshō 12 (1584), Munetsuna also attacked Koizumi Castle but the Hōjō came in support of the castle and attacked the base of the Nagao clan at the Ashikaga manor. Meanwhile, in the fourth month, Yoshishige and Kunitsuna deployed to Utsunomiya Castle and, from around 1575, aimed to recapture Koizumi Castle and attacked Oyama.
Course of events
The front line of the battle narrowly extended from east to west across the southern portions of Kōzuke and Shimotsuke provinces. At Numajiri, located in-between the environs of Koizumi Castle sought by the Hōjō and Oyama sought by the Utsunomiya, the two camps engaged in a violent clash. The Hōjō fielded 3,500 soldiers versus 3,000 soldiers among the Satake and Utsunomiya. The opposing forces arrived at Numajiri early in the fifth month and established bases, while a standoff ensued for 110 days without a decisive battle.
During this period, the two sides made provocations behind the bases of their enemies and cultivated support from others in more distant locations. Then, from the third month of 1584, the Battle of Komaki-Nagakute unfolded between the army of Hashiba Hideyoshi and the allied forces of Tokugawa Ieyasu and Oda Nobukatsu. The Satake and Utsunomiya engaged in frequent communication with Hideyoshi while, upon Hideyoshi’s orders, Uesugi Kagekatsu deployed to Shinano to contain the Hōjō. The Hōjō leveraged their settlement in the prior year with Ieyasu to establish an alliance to oppose Hideyoshi and, after this Battle of Numajiri, took steps to participate in the Battle of Komaki-Nagakute. After the Hōjō lured away Kajiwara Masakage (the second son of Ōta Sukemasa), concerns arose that the lines of communication would be severed between the Satake and their main base.
On 7/15, the Hōjō lured away Minagawa Hiroteru, a daimyō, and toppled the Iwafune encampment on Mount Iwafune along the route of retreat of the Satake and Utsunomiya forces. This is known as the Battle of Iwafuneyama. This event, in addition to movements by both sides in the hinterlands, provided momentum for peace negotiations and, on 7/27, a settlement. The next day, the parties decamped. Although the terms of the settlement are uncertain, it is surmised this included a return to the status quo existing prior to the attack on Koizumi Castle by the Yura and Nagao clans.
Although the battle itself ended in a draw, developments in the aftermath favored the Hōjō. Kajiwara Masakage yielded to the Satake again while the Yura and Nagao families were attacked by the Hōjō and surrendered within the year. After having their territory seized and being moved to Hishakuyama Castle, the two families endeavored to restore their previous spheres of influence. Upset at the situation, Makabe Ujimoto, a kunishū under the command of the Satake clan, sent a scathing letter to Satake Yoshishige as the Hōjō conducted individual attacks against landowners in the northern Kantō. On the first day of Tenshō 14 (1586), the death in battle of Sano Munetsuna in fighting against the Nagao clan triggered a succession struggle by which, ultimately, Hōjō Ujitada was adopted. That same year, Minagawa Hiroteru also surrendered to the Hōjō clan and the western half of Shimotsuke came under the influence of the Hōjō.
The Satake and Utsunomiya clans increased their dependency upon Hideyoshi and requested that he come to the eastern provinces, but, owing to differences with Tokugawa Ieyasu and operations relating to the Subjugation of Kyūshū, he repeatedly postponed a visit. In 1587, the Toyotomi administration issued an order to the Kantō and Ouu regions prohibiting individual conflicts between daimyō over territory or other matters. The Hōjō came prepared for war or peace, but, upon the urging of Ieyasu, on 8/22 of Tenshō 16 (1588), Hōjō Ujinori, a bushō, met with Hideyoshi in Kyōto and expressed his intention to yield allegiance whereupon he was recognized as a daimyō under the command of the Toyotomi. In a territorial dispute with the Sanada clan, mediation by Hideyoshi resulted in a favorable outcome for the Hōjō. Nevertheless, a refusal by the leaders of the clan, Hōjō Ujimasa and Hōjō Ujinao, to pay tribute to Hideyoshi in the capital led to a deterioration of relations. As both sides prepared for battle, in the eleventh month of 1589, an incident involving the occupation of Nagurumi Castle in Kōzuke Province led to the Conquest of Odawara whereupon, as long-desired by the Satake and Utsunomiya, Hideyoshi finally came to the eastern provinces.