The Battle of Mikatagahara, which ended in a decisive victory for the Takeda army

This resulted in the growing resentment of Shingen towards Ieyasu.

During the invasion of the Imagawa clan, Ieyasu Tokugawa established an alliance with the Takeda clan, with the condition that Totomi Province would become Tokugawa territory and Suruga Province would become Takeda territory. However, Shingen showed signs of taking over the eastern part of Totomi beyond the Tenryu River through Akayama Torashige, which led Ieyasu to harbor suspicions toward Shingen.

On the other hand, Kenshin Uesugi broke the Koetsu alliance in the first year of the Genki era (1570) to strengthen the Etsuso alliance. Immediately, Ieyasu intensified his negotiations for an alliance with Kenshin, and on October 8, the alliance between Uesugi and Tokugawa was established. At the same time as the alliance with Uesugi, Ieyasu severed ties with Shingen. Shingen attempted to prevent this by urging Oda Nobunaga to stop Ieyasu, but Nobunaga did not take any actions. From then on, Shingen’s dissatisfaction and resentment towards Nobunaga and Ieyasu grew.

Shingen stated that his invasion of Tokugawa territory in October of the third year of Genki (1572) was due to the “three years of pent-up frustration,” but this was based on the context of the establishment of the Uesugi-Tokugawa alliance and the dissolution of the alliance with Takeda.

Shingen believed that the alliance between Oda Nobunaga and Ieyasu Tokugawa (the Kiyoshu Alliance) placed Nobunaga in a superior position, with Ieyasu subordinate to him, and the Tokugawa clan being obedient to the Oda clan.

Therefore, when Ieyasu sought an alliance with Uesugi and plotted to break off the marriage proposal between Takeda’s daughter Matsuhime and Nobunaga’s legitimate son Nobutada, Shingen expressed intense resentment and requested that Nobunaga restrain Ieyasu. However, Nobunaga did not restrain Ieyasu. Both lords had their own political and military intentions and both supported Ashikaga Yoshiteru, so Ieyasu’s participation in the battles in the Kinai region was simply in response to the request of the shogunate.

However, the fact that Takeda and Tokugawa became adversaries ultimately led to a change in the relationship between the two, from one where Nobunaga held the advantage and Ieyasu was subordinate. Ieyasu, unable to confront Takeda alone, became dependent on Nobunaga for constant assistance in the form of reinforcements, provisions, and funds. This became a factor in Ieyasu’s subordination to the Oda clan. However, this tendency was not observed as long as Shingen was alive.

To reviving the Koetsu alliance, Takeda suddenly invaded Tokugawa territory.

In October of the third year of Genki, Shingen Takeda led a large army and invaded from Suruga into Totomi, heading towards Kojinyama Castle. The castle lord, Ogasawara Ujisuke, surrendered to Shingen by October 21. The main Takeda army advanced to Mikawa and repelled the Tokugawa army that had come for reconnaissance, proceeding to attack Hamamatsu.

Meanwhile, a separate unit of the Takeda army led by Yamagata Masakage and Akayama Torashige invaded Mikawa from Shinano with the cooperation of the Sanjo Clan, easily advancing to the border of Mikawa and Totomi provinces. Shingen had already bribed the Sanjo Clan in the previous year of the third year of Genki, so their movements were prearranged.

The Takeda army subjugated the Inui Castle of Totomi, the Akiyama Clan, and captured various castles such as Tadai Castle, Kamifukuoka Castle, Ichinomiya Castle, Iida Castle, and Mukai Castle, securing control over the Mitsuke and Fukuroi areas. They then advanced north along the Tenryu River, surrounding Futamata Castle. Shingen’s separate unit, led by Yamagata and others, joined forces at Futamata Castle, sealing off the water supply to the castle. As a result, the castle surrendered on the last day of November. The Takeda army conducted repairs on the castle and, on the early morning of December 22, began moving towards Hamamatsu Castle.

Meanwhile, Ieyasu received reinforcements of 3,000 troops, including Sakuemon Nobumori and Hirohide Hirate, from Nobunaga, but realizing that he had no chance of winning against the Takeda army, his Tokugawa retainers advised him to defend Hamamatsu Castle.

However, the Takeda army changed its course to Mikatagahara Plateau just before reaching Hamamatsu, indicating an intention to attack Mikawa, Ieyasu’s home province. Ieyasu marched out of Hamamatsu Castle, intending to pursue the Takeda army and launch a surprise attack from behind as they descended the Hoda slope from the Mikatagahara Plateau. However, Shingen feigned a retreat and deployed his entire army at Mikatagahara, waiting for the Tokugawa army.

The Takeda army provoked the Tokugawa army by throwing stones and dragged them into battle. The battle began around the hour of the monkey (around 4 p.m.). In this battle, the Tokugawa army collapsed in the face of the fierce Takeda attacks, and Ieyasu, with the help of his vassals serving as shields, barely managed to escape back to Hamamatsu Castle. The Tokugawa army suffered heavy casualties, with over 1,000 soldiers, including Nakane Masateru, Natsume Yoshinobu, Torii Tadahiro, and Honda Tadazane, killed in action. It was a resounding victory for the Takeda army.

Supervised and Written by Hirayama Yu

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