Tenshojingo War (天正壬午の乱)
The Tenshojingo War was fought between Ieyasu TOKUGAWA and Ujinao HOJO in the provinces of Kai, Shinano and Kozuke beginning in 1582.
Background
Nobunaga ODA, who started the subjugation of Takeda in April 1582, subverted the Takeda clan in Kai, and its territory--including Kai, Shinano, Suruga and Kozuke--was placed under the Oda government. Nobunaga established rules for his territory and divided the former territory of the Takeda clan among his vassals. Much of Kai was given to Hidetaka KAWAJIRI, but the two southeast districts of Yatsushiro and Koma, which were given to Nobukimi ANAYAMA, a relative of Takeda; Shinano Province was given to Nagayoshi MORI and others; Kozuke was given to Kazumasu TAKIGAWA; and Nobunaga returned to his province leaving them to govern their respective provinces. It is also said that Kazumasu TAKIGAWA was appointed to Kanto Kanrei (a shogunal deputy for the Kanto region) at that time. Although Ieyasu TOKUGAWA, who was Nobunaga's ally, was given Suruga as his territory, the Gohojo clan in the neighboring province of Sagami, which cooperated in the subjugation of the Takeda clan, was not given any of the former territory of the Takeda clan.
In July of the same year, Nobunaga was killed by his vassal Mitsuhide AKECHI in Honno-ji Temple, Kyoto (the Honnoji Incident). While Ieyasu TOKUGAWA--who was in Sakai City after a visit to Azuchi-jo Castle accompanied by Baisetsu ANAYAMA in order to show his appreciation for the increase of his own territory--escaped the hardship by traveling beyond Iga Province, Baisetsu, who departed later, was killed in Kyotanabe City on the Kizu-gawa riverfront (Kyoto Prefecture). In the postwar chaos, there were frequent uprisings of people in Kai Province, who were frustrated at new systems of governance such as the land survey and the ban on re-employment by a new lord. Hidetaka KAWAJIRI was abruptly killed on the battlefield, and Nagayoshi MORI had to withdraw to Mino Province. Furthermore, in response to the war, the Gohojo clan invaded districts in Kozuke and southeast Kai, and defeated an army of Kazumasu TAKIGAWA at the Kanna-gawa River on the border between Kozuke Province and Musashi Province (the Battle of Kanna River). Kazumasu abandoned Kozuke and withdrew to Ise Province. On the other hand, as soon as Shinano was evacuated, the Uesugi clan in the adjacent province of Echigo fought back to advance toward Kawanakajima.
The Process
As the news of Nobunaga's death spread from province to province, serious conflicts arose between different clans, including the Tokugawa, Hojo and Uesugi clans and the Sanada clan, which was striving to gain independence, over the former territory of the Takeda clan, which was left without a ruler. In Kai, Ieyasu TOKUGAWA, who had escaped to Okazaki, dispatched his vassals to Kai in an effort to seize the property inheritance of Baisetsu in the name of mobilizing a punitive force against Mitsuhide and supporting Hidetaka at the same time. He sent an old retainer, Nobushige YODA, to Saku, Shinshu. Nobushige gathered nearly 900 surviving retainers of Takeda by sending out circulars, and entered Komoro-jo Castle. Ieyasu, who had advanced the punitive army against Mitsuhide to Atsuta Ward (also said to have been Narumi), returned to Hamamatsu as soon as he heard that Mitsuhide was killed by Hideyoshi HASHIBA, who had just returned from the Chugoku region. In July and August, having ordered Tadatsugu SAKAI and Nobumasa OKUDAIRA to advance along the Shinshu road, Ieyasu himself entered Kai. He obtained the middle of the province and southern Shinano except for the districts suppressed by Gohojo, and entered Shinpu-jo Castle.
In Shinano, the major force led by Ujinao HOJO, who had defeated Kazumasu, continued its advance over Usui-toge Pass, and on June 26 (old calendar) made a show of power in Saku-gun. Masayuki SANADA offered a truce on July 9 (old calendar), ensuring safety in the Kozuke area, most of Hojo's troops focused their efforts on conquering Shinano and Kai. Ujinao also gave a certificate for the land to Yoshimasa KISO and Yoritada SUWA, and he seemed close to having Shinano within his grasp. However, Kagekatsu UESUGI got in his way. Kagekatsu, who was stationed in Shinano even after repelling Nagayoshi, displayed his wariness of Hojo, probably due to the influence of the Otate War, and was getting ready for battle. The armies of Hojo and Uesugi confronted each other at Kawanakajima; in fear of being attacked on both sides by Kagekatsu and Ieyasu, the Hojo clan made peace with Uesugi on the condition that four provides in northern Shinano be given to Kagekatsu; Ujinao then returned to Komoro-jo Castle, which he had seized from Nobushige YODA.
Now that the Hojo clan made peace with Kagekatsu, its only enemy was Ieyasu. On August 28, having learned that a great army of Hojo was coming, 3,000 soldiers led by Tadatsugu SAKAI, who were attacking Takashima-jo Castle of Yoritada SUWA on Hojo's side, backed away, and 43,000 soldiers led by Ujinao HOJO chased them via Saku. However, those on Tokugawa's side successfully retreated to Shinpu-jo Castle. The pursuing army of Hojo also entered Kai and encamped in Wakamiko, where they confronted the army of Ieyasu in Shinpu-jo Castle (September 2). On the sixth, Ieyasu moved his camp to Shinpu-jo Castle, entrusting Fuchu to 2,000 soldiers led by Mototada TORII, which made the army of Tokugawa 8,000 in total. He also pinned Ujitada HOJO and Ujikatsu HOJO to Misaka-toge Pass, and compelled Ujikuni HOJO to observe Kai from Chichibu City. When the Hojo troops entered Kai, Nobushige launched guerrilla attacks on groups of Hojo's troops carrying supplies.
On September 8, 10,000 soldiers led by Ujitada and Ujikatsu advanced to the Gunnai district in eastern Kai, in order to attack Ieyasu from behind. Two thousand soldiers led by Mototada TORII and Yasusada MIYAKE bravely received them near Tsuru City, and defeated them by killing about 300 of Hojo's soldiers (the Battle of Kurokoma). After this battle, the fighting became remarkably disadvantageous for Hojo. On September 18), Yoshimasa switched to Ieyasu's side. In September and October, Masayuki, who had left the umbrella of Hojo as a result of the peace made between Hojo and Uesugi, gave his support to Nobushige, and Ieyasu enhanced his military power by having Masatada SONE assist Nobushige and Masayuki. In October and November, Masayuki killed a member of the Nezu family and Nobushige attacked Komoro-jo Castle to get rid of Masashige DAIDOJI. In southern Shinano, Sadayoshi OGASAWARA, who was supported by Ieyasu, followed Yoshimasa and entered his former territory, Fukashi (present-day Matsumoto City); other lords also took the side of Ieyasu. With the guerrilla attacks of Nobushige and Masayuki also increasing in severity, Hojo's supply line was practically severed. Although Hojo dispatched a small army to Kozuke and Saku, the battle didn't turn in his favor. Furthermore, in response Yoshishige SATAKE (the eighteenth head of the family) intensified his activities in the Kanto Plain. At this point, Hojo finally determined to make peace with Ieyasu. The pacification was made on November 24.
The conditions of the pacification include the following:
Ujinao should marry Tokuhime (Princess Toku), a daughter of Ieyasu. Ieyasu should be allowed to seize territories freely in Kai and Shinano while Hojo should be allowed to do the same in Kozuke, extending their power in their respective areas without interfering with each other.
The battle ended in this manner from a general standpoint. Subsequently, however, Nobushige YODA, who was on Ieyasu's side, was killed in battle in the northern region, and Masayuki SANADA, a former vassal of Takeda who had also served under Nobunaga ODA, resided in the newly built Ueda-jo Castle, resisting the rule of the Tokugawa clan with the support of the Uesugi clan. This was because the conditions of the pacification between Tokugawa and Hojo included an article that Tokugawa should rule Shinano and Hojo should rule Kozuke, and it is also said to be because Masayuki--who had territories in Numata City, in Kozuke, in addition to Shinano--was afraid of losing his own territory there. Ieyasu dispatched an army to attack Ueda-jo Castle in 1585, which failed due to a counterattack by Sanada (the Battle of Ueda).
The situation was finally saved by Hideyoshi TOYOTOMI in 1589, and a majority of Sanada's territories around Numata passed to the Hojo clan. However, the remaining territories of Sanada were taken by the army of the Hojo clan, causing a series of incidents that finally led to the Battle of Odawara.
Furthermore, Naomasa II, who was an envoy of Tokugawa for the pacification, gained surviving retainers of Takeda in a series of such battles, and he organized 'Ii army,' which won a name for itself as 'Akazonae' (red arms).