Tokugawa Ieyasu: Following the “Shingen Style” in Secret

Achieving Unity Under the “Ieyasu School” by Incorporating the Kai and Shingen Styles

Young men who were influenced by Shingen’s teachings were numerous. Various individuals, including the inner circle, relatives, and castle-town commoners, were educated by Shingen as their “master”, and they grew into top-notch warriors. Among the Kai Province troops, these individuals, who learned everything attributed to the Kai and Shingen styles (military organization, martial tactics, economic systems, etc.), one of them being Tokugawa Ieyasu.

Certainly, Ieyasu was never in the same place as Shingen, but whether during times of hostility or temporary alliances, he closely observed Shingen’s methods and tried to incorporate them into his own style, shaping it into the “Ieyasu School”.

Among the warriors of his time, it is likely that only Ieyasu truly understood Shingen’s strength, greatness, and terror. For this reason, Ieyasu regarded Shingen as his “lifetime master” and sought to understand Shingen’s ways and live in a similar manner. The result of this dedication was his attainment of the title of “tenka no hito” or ruler of Japan.

In March of 1582, the Takeda clan, led by Katsuyori, met its demise. At this time, Oda Nobunaga ordered, “Kill any renowned Kai Province warriors you find”, and proceeded to massacre the Takeda retainers.

However, Ieyasu did not follow Nobunaga’s orders. When he learned about Kai Province warriors, he hid many of them and helped them escape to places where Nobunaga’s influence did not reach, such as Suruga. Even though Katsuyori’s downfall occurred, it is believed that there were at least 3,000 to 4,000 Takeda retainers remaining at this point. Ieyasu wanted these Kai Province warriors.

In June, after Nobunaga’s death in the Incident at Honnō-ji, Ieyasu, before confirming Nobunaga’s death, sent a letter to his retainer Okabe Masatsuna, instructing him to “move to Kai and Shimo-yama (places in Kai Province) and build a castle in a better location.” Furthermore, he dispatched Honda Masanobu to Kofu to search for surviving Takeda retainers. This led to the “Tenshō-Jingo no Tatakai,” a three-way struggle over Kai and Shinano provinces involving the Tokugawa, Uesugi, and Hōjō clans, following the Incident at Honnō-ji.

Ieyasu called out, “If you serve the Tokugawa, all of the Takeda retainers will be treated in the same territories as during the Shingen and Katsuyori eras. We will not inquire about the past. Those who wish to join, everyone, come forth”. Among those who responded to Ieyasu’s call were Iida Genba and Sanada Nobutada. Responding to these calls, 1107 individuals (or 895, depending on sources) joined Ieyasu.

For instance, a man named Magaribuchi Shōzaemon, during the Takeda era, held a fief of 100 koku (a unit of measurement for land and wealth). Ieyasu rewarded Magaribuchi by granting him 500 koku in Sagami Province.

Ieyasu, who cherished the most beloved warrior, Ii Naomasa, ordered him to reorganize the symbolic “Akazonae” unit of the Takeda forces. He also assigned Takeda’s former retainers associated with Akazonae to Naomasa. This became the later “Ii Clan’s Akazonae”, and it was the reason Naomasa was called the “Red Devil of Ii”.

Ieyasu experienced a defeat that he would never forget. It was the Battle of Tōtōmi-Mikatagahara on December 22, 1572. Facing Shingen’s Takeda army of 25,000, combined with 3,000 reinforcements from Nobunaga, the Tokugawa-Oda coalition numbered 12,000. Ieyasu, recklessly confronting the Takeda forces who passed by him with Hamamatsu Castle in their sights, suffered a devastating defeat with casualties reaching as high as 1,200, including samurai-class casualties. There were countless wounded.

Ieyasu fled and, in his state of terror, defecated while still on horseback before reaching Hamamatsu Castle. A self-portrait he had drawn during that time, now displayed in the Tokugawa Art Museum, depicts him sitting on a stool, clutching his left leg, resting his left hand on his chin, and looking dejected, known as the “Ieyasu no Shikami-zō” (Ieyasu’s Depressed Self-Portrait). This self-portrait is said to reflect Ieyasu’s admiration for Shingen. In other words, Ieyasu, by having this pitiable image of himself painted in the aftermath of his defeat, intended to use it as a source of motivation for his future self.

Among the Takeda’s former retainers who served Ieyasu, there were individuals like Ōkubo Nagayasu, who supported the early Tokugawa government as Kanayama Bugyō and Tairō (high-ranking officials), Kaganoi Shōzaemon’s son Kagenori, who established the “Kai-style Military Studies”, and Yoshimasu, a grandson of Yanagisawa Seiheiji, who became Tairō.

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