Known as "the Tiger of Kai", he was one of the most powerful daimyo of the late Sengoku period, and credited with exceptional military prestige.

[1] Shingen was based in a poor area with little arable land and no access to the sea, but he became one of Japan's leading daimyo.

Shingen was called "Tarō" (a commonly used pet name for the eldest son of a Japanese family) or Katsuchiyo (勝千代) during his childhood.

It was a common practice in feudal Japan for a higher-ranking samurai to bestow a character from his own name to his inferiors as a symbol of recognition.

[4][5] At some point in his life after his "coming of age" ceremony, the young man decided to rebel against his father, Takeda Nobutora.

Events regarding this change of leadership are not entirely clear, but it is thought that Nobutora had planned to name his second son, Nobushige, as his heir instead of Shingen.

A number of the major warlords in the Shinano region marched on the border of Kai Province, hoping to neutralize the power of the still-young Shingen before he had a chance to expand into their lands.

Taking advantage of their confusion, Shingen was able to win a quick victory, which set the stage for his drive into Shinano lands that same year and his successful Siege of Uehara.

Shingen uncovered two plots on his life, the first from his cousin Suwa Shigemasa (whom he ordered to commit seppuku), and the second, a few years later, from his own son Takeda Yoshinobu (武田義信).

By 1567, nonetheless, after Shingen had successfully kept the forces led by Uesugi Kenshin out of the northern boundaries of Shinano Province, taken over a strategically important castle in western Kōzuke, and suppressed internal objection to his plans to take advantage of the weakened Imagawa clan, he was ready to carry out his planned Suruga invasion.

By the time Takeda Shingen was 49 years old, he was the only daimyō with the necessary power and tactical skill to stop Oda Nobunaga's rush to rule Japan.

In 1572, upon securing Takeda control over Suruga, northern Shinano, and western Kōzuke, Shingen advanced to Totomi Province, and took Oda's Iwamura Castle, which caused the Takeda–Oda relationship to decline.

Once he entered Mikawa Province in February 1573, Shingen besieged Noda Castle, but then died in his siege camp at the age of 51.

Upon Takeda Shingen's death, Uesugi Kenshin reportedly wept at the loss of one of his strongest and most deeply-respected rivals.

[11] However, historian Kazuto Hongō viewed that despite the advantage of advanced military doctrines and administration systems established by Shingen, his efforts failed to prosper the Takeda clan themselves.

Hongō stressed the failure of Takeda clan during Shingen period to build a war economy, as he examines that the 20 years of effort of Shingen conquest to subjugate Shinano province, in complement with his series of exhausting engagements against his rival Kenshin, he only managed to secure the territories which only yield gross annual rice production of 600,000 koku as revenue at most, which translates this means the optimal military mobilization of Takeda clan were at maximum only 20,000 soldiers for each campaign.

[12] One of the most lasting tributes to Shingen's prowess was that of Tokugawa Ieyasu himself, who is known to have borrowed heavily from the old Takeda leader's governmental and military innovations after he had taken leadership of Kai Province during Toyotomi Hideyoshi's rise to power.

[13] Then furthermore, on the aftermath of the war, Ieyasu immediately organized a kishōmon(blood oath) ceremony with the former vassals of Takeda clan to declare their loyalty to the Tokugawa clan, which resulted in:[14][15][16][17] Historian Masaru Hirayama argued, the outcome of this war which involved the absorption of Takeda retainers into Tokugawa ranks was not only just factional conflict in the eastern province, but it determined the unification of Japan in the future, as it pushed Tokugawa Ieyasu into the key position of Toyotomi government.

[21] The second occasion of the further incorporation of Takeda clan's vassals occurred on November 13, 1585, when Ishikawa Kazumasa defected from Ieyasu to Hideyoshi.

Later, he also appointed two former Takeda vassals, Naruse Masakazu and Okabe Masatsuna, as magistrates under authority of Ii Naomasa and Honda Tadakatsu, while he also ordered all of former Takeda vassals who now serve him to impart any military doctrines and structures they knew during their service under Takeda clan.,[23] and lastly, he ordered the three of his prime generals, the so-called "Tokugawa Four Heavenly Kings," Ii Naomasa, Honda Tadakatsu, and Sakakibara Yasumasa, to serve as supreme commander of this new military regiments.

[24] Those statecrafting doctrine which Ieyasu practiced and learned from Shingen's former vassals greatly benefitted him in the long run, as being proven on the future, such as when Ieyasu transferring his powerbase to Kantō region in 1590, as he established new offices such as the Hachiōji sen'nin-dōshin, which formed from patchwork memberships from 9 small clans of Takeda retainers.

This group will continue to serve the Tokugawa clan faithfully as defender of Kai province during this period in service of Ieyasu.

[26] While professor Watanabe Daimon also similarly stated that The Kai province samurai greatly influenced Ieyasu's domination of Japan.

[27] According to an anecdote from “Meisho Genkoroku” (Collection of words and deeds of great commanders in Japanese history), when Nobunaga sent a head of Takeda Katsuyori to Ieyasu, Ieyasu remarked in the front of the former Takeda clan followers his head that although Katsuyori was a biological son of Shingen, but that he was the "spiritual successor" of Shingen.

The love pact signed by the two, in Tokyo University's Historical Archive, documents Shingen's pledge that he was not involved in, nor had any intentions of entering into, a sexual relationship with a certain other retainer, and asserts that "since I want to be intimate with you" he will in no way harm the boy, and calls upon the gods to be his guarantors.