Minamoto no Yoritomo and the Founding of the Kamakura Shogunate

In Jishō 4 (1180), Minamoto no Yoritomo, who had been exiled to Izu, raised an army in response to the ryōji (princely decree) of Prince Mochihito. In the first engagement, the Battle of Ishibashiyama, he was defeated by the large army of Ōba Kagechika and barely escaped with his life. He then crossed to the Bōsō Peninsula, rallied eastern warriors such as Chiba Tsunetane and Kazusa Hirotsune, and within only a few months established control over the Kantō.

Yoritomo's uprising was not simply a military campaign to overthrow the Taira. By guaranteeing the eastern warriors a practical benefit, shoryō ando (confirmation and guarantee of landholdings), he won the organized support of the warrior bands. This was fundamentally different from the aristocratic (kuge) government's method of gathering support by dispensing grace, and it was the seed of a political system by warriors, for warriors.

From Dan-no-ura to the Installation of Shugo and Jitō

In the 3rd month of Genryaku 2 (Juei 4; 1185), the Taira were destroyed in the naval battle at Dan-no-ura. But the real architect of victory at that point was his younger brother Minamoto no Yoshitsune, while Yoritomo himself remained in Kamakura, devoting himself to organizing the governance of the east.

After the Taira's fall, under the pretext of tsuibu (pursuit and arrest) of Yoshitsune, in the 11th month of Bunji 1 (1185), Yoritomo obtained from Retired Emperor Go-Shirakawa the right to install shugo (military governors) and jitō (land stewards) in the provinces. This is regarded as the decisive moment in the founding of the Kamakura bakufu. Shugo held military and policing authority in each province, while jitō were responsible for managing shōen (estates) and kokugaryō (provincial public lands) and collecting annual dues. Through this dual structure, warriors were institutionally guaranteed substantive management rights even over shōen held by aristocrats and temples and shrines.

The Meaning of Warrior Government and Japanese Sword Culture

Although the warrior class had continued to grow since the late Heian period, real political power remained in the hands of the aristocratic and imperial system of the regent houses (sekkan-ke) and insei (rule by retired emperors). The founding of the Kamakura bakufu fundamentally changed that structure. With warriors seizing political and military power, the conditions were set for warrior values, including the pride of those who bear swords, reverence for martial valor, and the duty between lord and vassal, to rise as the norms of Japanese society as a whole.

By the late Heian period, the Japanese sword had already been perfected into a form close to the present one: a single-edged blade with a curve. In the age of the Genpei War, mounted archery (kisha, archery from horseback) was the mainstay of combat, and the long tachi with a pronounced curve was a weapon that complemented it. The Kamakura period became the golden age of the Japanese sword.

The great swordsmiths later called the "age of famous swords" were active precisely in this Kamakura and Nanboku-chō period. They include Masamune (Sōshū-den), Kuniyuki (Rai school), Ichimonji (Bizen Ichimonji), and Kunimune (Bizen Saburō Kunimune, mid-Kamakura period). Through the gokenin system of shogun and vassals, the bakufu ritualized swords as "proof of the lord-vassal bond," and the gift-giving of famous swords became a symbol of political authority.

Yoritomo and Swords

Yoritomo moved Tsurugaoka Hachimangū to its present site and built the bakufu's facilities around it. Together with the white banner of the Minamoto, the sword became the symbolic center of the Kamakura warrior.

Among the famous swords later called the Tenka Goken (Five Great Swords under Heaven), namely Dōjigiri Yasutsuna, Onimaru Kunitsuna, Mikazuki Munechika, Ōdenta Mitsuyo, and Juzumaru Tsunetsugu, Onimaru Kunitsuna is a sword that was passed down to the Hōjō clan (the shikken regents' house) and is discussed in connection with the Kamakura bakufu. Kunitsuna was a swordsmith of the Awataguchi school of the Kamakura period, and is a figure who symbolizes the advancement of swordsmithing techniques under bakufu rule.

The Gokenin System and the Ceremonial Status of Swords

The gokenin system that Yoritomo established was based on a mutual obligation between "service and favor" (hōkō and go'on). In return for gokenin risking their lives in service to the shogun, the shogun confirmed their landholdings and showed his favor through grants of swords, armor, horses, and other gifts. In this context, the sword went beyond being a mere weapon and became a vessel that embodied the bond with one's lord, and carefully keeping and passing down the swords one had received was regarded as the essential duty of a warrior.

This custom spread throughout warrior society, and through the Muromachi, Sengoku, and Edo periods it developed into a culture of preserving "received tachi" as family treasures. The many famous swords handed down to the present day that carry the provenance "received from ○○" are the direct legacy of the ceremonial order established in this Kamakura period.

Consolidation of the Bakufu System

With the subjugation of the Ōshū Fujiwara in Bunji 5 (1189), Yoritomo brought even the Tōhoku region under his territory and completed the first warrior government to effectively control all of Japan. In Kenkyū 3 (1192), he was appointed Sei-i Taishōgun, and the bakufu was completed in the legal sense.

That said, from the standpoint of historical scholarship, the installation of shugo and jitō in 1185 is often regarded as the true beginning of warrior government. The academic consensus shifted from the traditional mnemonic "ii kuni (1192) tsukurō Kamakura bakufu" to "ii hako (1185) tsukurō Kamakura bakufu" as a result of reassessing the significance of this installation of shugo and jitō.

The founding of the Kamakura bakufu marked the beginning of roughly 700 years of warrior government, in which warriors became the main force in Japanese society. It was also the starting point of a long history in which the Japanese sword rose from a mere weapon to a cultural symbol at the core of bushidō, art, and ritual.