Tenshō-Jingo War (天正壬午の乱, Tenshō-Jingo no ran) or more simply, the Battle of Jingo (壬午の役, Jingo no eki), was a three-way military conflict in 1582 AD (10th year of Tenshō) between Hōjō clan, Tokugawa clan, and Uesugi clan.
The conflict occurred due to the three clans' bid to gain control of former Takeda clan territories at Kai, Kōzuke, and Shinano province post Oda Nobunaga's death. The conflict ended with peace negotiation in 1583 with the Hōjō clan sent Hōjō Ujinobu as representative, while the Tokugawa sent Ii Naomasa as representative
Background
In 1582, after the extermination of
Takeda clan in Kai Province at the battle of Tenmokuzan, Nobunaga gave Ieyasu the right to govern Suruga Province in recognition of his service in the fight against the Takeda clan.
However, soon enough Oda Nobunaga was assassinated at Honnō-ji, a temple in Kyoto, on 21 June 1582 (2nd day of the sixth month, Tenshō 10), by his own vassal Akechi Mitsuhide. Tokugawa Ieyasu, Nobunaga's ally, heard the news of The death of Oda Nobunaga while he was at Hirakata, Osaka, but at the time, he had only a few companions with him.
The Tokugawa group escaped the chaos through Kada Pass, where they reached the territory of the friendly Kōka ikki clans of Jizamurai. The Koka ikki assisted Ieyasu in eliminating the threats of the Ochimusha-gari outlaws and escorted them until they reached Iga Province, where they were further protected by other friendly groups of Iga ikki which accompanied the Ieyasu group until they safely reached Mikawa. After Ieyasu reached Mikawa, he immediately moved to shift his focus to former Takeda clan territory as he expected unrest there. As a preemptive measure, Ieyasu dispatched Honda Nobutoshi to contact Kawajiri Hidetaka, who ruled Suwa District as a vassal of the Oda clan, to request cooperation, While at that moment, ex Takeda clan vassal Yoda Nobushige pledges his allegiance to Ieyasu.
At the same time, Uesugi and the Hōjō clans also mobilized their forces to invade Shinano Province, Kōzuke Province, and Kai Province (currently Gunma Prefecture), which were ruled by the remnants of the many small clans that formerly served the Takeda clan, when they learned of the death of Nobunaga. This caused a triangular conflict between those three factions.
Preliminary movements
At first, the Hōjō clan, who ruled the Kantō region, led an army of 55,000 men to invade the Shinano Province through Usui, as they aimed to prevent a Tokugawa incursion of Kai.
On June 5, Kawajiri Hidetaka instructed Yonekura Tadatsugu and Orii Tsugumasa to work to get the Kai warriors to join the Tokugawa side and to wait for Ieyasu to invade Kai.
Following this, Ieyasu also transmit similar instructiom for Orii Tsugumasa and Yonekura Tadatsugu, who both hailed from Takekawa clan of Kai province and hiding in Kiriyama, Tōtōmi Province, to proceed with the work of enticing the Kai samurai to the Tokugawa side. The next day, Ieyasu also sent a letter to Masatsuna instructing him to begin the construction of a castle at Shimoyama, Minobu Town in the Kai Kawachi domain, the former base of Anayama Nobutada, one of Tokugawa's retainers who was killed by outlaws during his escape after the Honnō-ji Incident. Suganuma Castle (Terazawa, Minobu Town) was built along the Fuji River and the Suruga Highway (Kawachi Road). After the death of Nobutada and the senior members of the Obikane clan, to which they had pledged loyalty, the Anayama clan was left leaderless, so they decided to pledge allegiance to Ieyasu.
Conflict chronology
Ieyasu immediately marched his 8,000 soldiers to the disputed regions and then split his army into two parts, with the separate detachment led by Sakai Tadatsugu and Ogasawara Nobumine going to pacify the Shinano Province, while Ieyasu took the main force to pacify Kai. Tadatsugu and Nobumine met with unexpected resistance from Suwa Yoritada, a former Takeda vassal who was now allied with the Hōjō clan.
Tadatsugu's force then beaten by Yoritada, who were then reinforced by the Hōjō clan, forcing Tadatsugu to retreat. As Tadatsugu's forces retreated, they were pursued by 43,000 men of the Hōjō clan army. Okabe Masatsuna, a member of the Suruga clan samurai who once served under Baba Nobuharu, took the initiative to defend the rear of Tadatsugu's army from the enemy charges and repelled them. As they successfully retreated without further losses, they rejoined Ieyasu's main forces in the area of Wakamiko in Suwamachi (modern day Yamanashi Prefecture). Ieyasu then dispatched Sone Masatada, formerly one of Shingen Takeda's three most prominent generals, to the Erinji area with 500 men to confront a Hōjō force that numbered 3,000 men. Masatada managed to defeat them and inflicted between 600 and 700 casualties.
On April 3, Oda Nobukatsu wrote to Ieyasu about the situation at Ise Province, while Ieyasu reported that he had pacified the Ogata and Saku District, Shinano Province. The two maintained close contact from then.
By 11 June, the Hōjō started constructing Misaka Castle at Fujinoki, Misaka-cho, Fuefuki City, or in Kawaguchi, Minamitsuru District, Yamanashi In June 12, Masatada joined forces with another former Takeda vassal, Okabe Masatsuna, and a senior Tokugawa general, Osuga Yasutaka. The same day, Yoda Nobushige set off to Saku District and rallied around 3,000 Takeda clan retainers as Ieyasu instructed. Several days later, Osuga Yasutaka, a senior Tokugawa vassal, inspected Masatada's troops, where he commended the cooperation of Masatada lieutenant, Kubota Masakatsu. By June 13, the Hōjō clan had captured Iwadono Castle in Tsuru District and instructed Watanabe Shozaemon, a local magistrate from the Tsuru District, to assist them in their conquest. Subsequently, Sanada Masayuki led his army and captured the Numata Castle for the Uesugi clan.
On June 14 however, Kawajiri Hidetaka killed Honda Nobutoshi. This was followed by an uprising from many of the clans in Kai province against Hidetaka the following day, which resulted in Hidetaka being killed on June 18. It is said that after his death, Hidetaka's body was buried in unusual way, upside down with his head at the bottom. This was because his tyrannical rule in Kai Province made its people despise him so much. For this reason, Kawajirizuka, which is believed to be his grave, is also known as Sakasazuka.
As the triangular battle was underway between the three factions, order was restored in Owari province as the rebellion of Akechi Mitsuhide had already been suppressed in the Battle of Yamazaki. Ieyasu also informed the Oda clan of the developments in Shinano and Kai. On 19 June, Hideyoshi informed Ieyasu that order in Kamigata area has been restored as there is nothing to be worried About. In response, Ieyasu return to Hamamatsu. Meanwhile, Takigawa Kazumasu also defeated by Hōjō Ujinao at the battle of Kanagawa.
Later, the Hōjō also gained support from the Hoshina clan, which was a former Takeda vassal, led by Hoshina Masatoshi and his sons Hoshina Masanao and Naitō Masaaki. On the other hand, the Tokugawa clan gained support from the Tomohisa clan.
Uesugi clan's movement
Uesugi Kagekatsu of the Uesugi clan also made his move by supporting former Takeda clan forces under the leadership of Ogasawara Dōsetsusai from the Ogasawara clan and Yashiro Hidemasa at Chikuma and the Nishina clan of Azumino. They defeated and expelled Kiso Yoshimasa, who had been granted the control of both Chikuma and Azumino by Oda Nobunaga. They then faced another branch of Ogasawara clan which was led by Ogasawara Sadayoshi and his retainers which opposed the steps taken by Dōsetsusai. Sadayoshi's group appealed to the Tokugawa clan and offered their allegiance to Ieyasu. Kagekatsu assigned Yamaura Kagekuni, son of Murakami Yoshikiyo, to control the counties of Sarashina, Hanishina, Takai , and Minauchi. Meanwhile, Sanada Masayuki and his brother, Sanada Nobutada, also submitted to the Uesugi clan and was assigned to Makinoshima Castle.
Starting from 23 June onwards, Ieyasu's vassal Osuga Yasutaka worked together with former Takeda clan vassals such as Sone Masatada, Masasuke Ariizumi, and Okabe Masatsuna distributing letter of intents about fiefs appointment in Shinano.
On June 24, Kagekatsu advanced into northern Shinano and entered Naganuma castle. In the same day, Masayuki submitted to Uesugi Kagekatsu.
On June 28, Ieyasu further dispatched another detachments led by Okubo Tadayo, Ishikawa Yasumichi, and Honda Hirotaka and his son Yasushige to Kai as reinforcements in an attempt to win over the local samurai clans in Kai and Shinano which still remained neutral. Subsequently, Ieyasu also dispatched the Anayama clan to resist the Hōjō clan. He also sent his generals Ōkubo Tadayo, Ishikawa Yasumichi and Honda Hirotaka along with his son Yasushige as reinforcements for them to resist the Hōjō. By the end of June, the Hōjō clan had secured all of the territory except for the areas controlled by the Sanada in Numata and Agatsuma.
On July 7, as the Oda clan learned of the defeat of Takigawa Kazumasu by the Hōjō clan at the Battle of Kanagawa, Toyotomi Hideyoshi sent a letter to Ieyasu to give him authorization to lead military operations to secure the two provinces of Kai and Shinano from the Hōjō and Uesugi clans. Ieyasu then deployed his forces to various fortresses in the Kōfu Basin to oppose Ujinao, who had camped his army in the area of present-day Hokuto City. Hattori Hanzō led Iga clan warriors to Katsuyama Castle (Kamisone-cho, Kofu City), Minakuchi Castle, and Kotohirayama Castle (Misakuchi-cho, Kofu City), where he monitored the Nakamichi road connecting Kai and Suruga.
Uesugi withdrawal
On July 9, Masayuki changed his allegiance from the Uesugi to the Hōjō when he surrendered to Hōjō Ujinao, and began building a system of forifications to station his vassals in Ueno Province. His brother, Nobutada, also submitted to the Hōjō on the same month. However, Nobutada expelled from his castle by Hōjō's representative, Yamada Ukon-no-jo, who refused the negotiation term with Nobutada.
Subsequently on July 12, as the troops under Hōjō Ujinao advanced across the Usui Pass, Nobushige resisted them, but then he abandoned the Komoro Castle and retreated to a fortress which he deemed more suitable to defend against the Hōjō army. Later on July 16, Sadayoshi launched an attack on Fukashi Castle, forcing Dōsetsusai along with Hidemasa to surrender. Ujinao advanced his troops while leaving the siege against the castle to his general, Daidōji Masashige. Meanwhile, the Hōjō negotiated a truce with the Uesugi in July 19, so they could focus their front towards the Tokugawa in Kai province, much to the dismay of Masayuki, as he had hoped to secure his territory in Numata instead of from the Uesugi.
The resistances of local warlords against Hōjō increased further this time, as an Ogasawara clan branch in Mishima Izu province under Ogasawara Hirokatsu also defied the Hōjō clan. The Hōjō clan defeat them in a battle where Hirokatsu's father was killed. Thus, Hirokatsu retreated to Mitsuba Castle in Suruga province. Meanwhile, the Enoshita clan, another local clan subject to the former Takeda clan, which was led by Enoshita Norikiyo, also showed their resistance against the Hōjō when they fought and beat a detachment of Hōjō troops at the Battle of Sakaguchi.
Stalemate
On August 6, the main body of the Tokugawa army led by Ieyasu met with the Hōjō clan's main army that was stationed at Wakamiko castle. Ieyasu deployed Matsudaira Kiyomune, Torii Mototada, Naitō Nobunari, and Mizuno Katsunari to guard the area. This place became known by historians as "Wakamiko face-off", where 8,000 Tokugawa soldiers atands against approximately 50,000 Hojo soldiers led by Hōjō Ujinao. As Ieyasu's forces lined up at Shinpu and Nomi Castles to the north and fortified their defenses, various skirmishes broke out, where the smaller Tokugawa forces managed to stall the much larger Hōjō forces. In the middle of these engagements, Sakakibara Yasumasa stormed a castle which occupied by the Hōjō, while Matsudaira Ietada was harassing the Hōjō food supplies.