The Zenkunen and Gosannen Wars (1051-1087) and Japanese Swords: The Warrior Culture Cultivated by the Minamoto Clan in Eastern Japan

The Earlier Nine Years' War and Later Three Years' War—An Age of Warrior Clan Rise in Tohoku

Late in the Heian period, two large-scale civil conflicts occurred in succession on the stage of Mutsu Province (present-day Tohoku region). These were the Earlier Nine Years' War (1051–1062) and the Later Three Years' War (1083–1087). These conflicts were far more than merely local rebellions; they were a historical turning point that determined the rise of the Minamoto warrior clan, which would later establish the Kamakura shogunate, and they would have a profound impact on the development of the Japanese sword.

The Earlier Nine Years' War began when the imperial court dispatched Minamoto no Yoriyoshi as the governor of Mutsu Province in response to the expansion of power by the Abe clan, a powerful local magnate in Mutsu. With aid from the Kiyohara clan, Yoriyoshi destroyed the Abe clan, and through this military achievement the Minamoto established a solid foundation in the eastern provinces. In the subsequent Later Three Years' War, Minamoto no Yoshiie (Hachiman Tarō Yoshiie) intervened in the internal conflicts of the Kiyohara clan and pacified them, making the position of the Minamoto as the "head of the warrior clans" in the eastern provinces immovable.

The Practicality That Tohoku Battlefields Demanded of Swords

The terrain of Tohoku where the Earlier and Later Three Years' Wars unfolded provides important context for understanding the development of swords during the Heian period. While battles in mountainous and forested regions centered on the exchange of arrows from horseback, in mounted grappling and close combat the practical utility of swords played a decisive role in determining victory and defeat.

The Japanese swords of this era are positioned in the early stage of the "old sword period" (kotaki). The dominant type was a slender tachi with strong kosori curvature, designed on the premise of single-handed operation while mounted. Blade length of approximately 2.7 to 3 shaku (roughly 82–91 centimeters) was standard, and the characteristics of the tachi from the mid-to-late Heian period were deep curvature and a relatively small kissaki.

In one of the fierce battles of the Earlier Nine Years' War, the Battle of Kinomi in 1057, the father and son Minamoto no Yoriyoshi and Yoshiie suffered a major defeat at the hands of Abe no Sadatō's forces. The record of this defeat states that "many soldiers were killed in close combat after running out of arrows," conveying the fierceness of hand-to-hand combat with swords. In contrast, at the Battle of Kuriyagawa in 1062, Yoshiie's forces, reinforced by the Kiyohara clan, achieved an overwhelming victory, killing Abe no Sadatō and bringing the conflict to an end.

Minamoto no Yoshiie and the Establishment of "the Way of the Bow and Arrow"

The exploits of Minamoto no Yoshiie in the Later Three Years' War (1083–1087) would come to be passed down to later generations as the origin of Japanese bushidō. Particularly famous is the anecdote of the "scattered wild geese." This story, in which Yoshiie perceived the presence of hidden troops after observing a flock of wild geese in flight suddenly scatter during a military advance and thus escaped danger, is widely known as a symbol of a military commander's insight.

Yoshiie was renowned not only as an excellent archer but also as a master swordsman. The warriors who served him were based in the eastern provinces and pursued the cutting edge of practical sword-forging techniques of the time. Mutsu Province was also known as a source of iron sand, and it has been suggested that the iron-working culture of Tohoku may have been utilized in sword production.

The Iron-Working Culture of Tohoku That Supported the Sword Industry

The Tohoku region in the Heian period was important not only as a battlefield but also in terms of iron-working technology. Extensive iron sand deposits spread throughout Ōshū (Mutsu and Dewa), and local iron workers actively engaged in iron sand refining. It is believed that this iron culture of Tohoku supported the supply of weapons to the Minamoto warrior clan.

Multiple traces of sword production have been confirmed in the area surrounding Hiraizumi, the center of the Ōshū Fujiwara clan. Archaeological investigations have uncovered blacksmith sites dating from the late Heian through early Kamakura periods throughout Tohoku, gradually revealing the realities of regional sword production.

On the other hand, many of the warriors who participated in the Earlier and Later Three Years' Wars were from the Kantō (Bandō) region, and the swords they used are believed to have been primarily ordered from prominent sword makers in Kyoto, Yamato, and Bizen. While local blacksmiths handled the repair and replenishment of weapons during expeditions, the production of excellent swords remained the domain of the sword-making groups in the central regions.

The Sword Culture of the Minamoto Warrior Clan and Its Legacy

The sword culture of the Minamoto established through the Earlier and Later Three Years' Wars directly influenced the view of swords in later military governments. Within the genealogy of the Minamoto continuing from Yoshiie to Yoritomo, swords came to be positioned not merely as weapons but as symbolic representations of warrior authority and legitimacy.

Particularly noteworthy is that the Minamoto made Hachiman their tutelary deity and established the custom of dedicating swords to the Tsurugaoka Hachiman Shrine (in Kamakura). This dedication culture originated in prayers for victory and offerings of gratitude in the Earlier and Later Three Years' Wars, becoming a precedent for later sword dedications to shrines by the warrior class.

Moreover, the "virtuous tale of Yoshiie," in which Yoshiie, not rewarded by the imperial court for his military achievements in the Later Three Years' War, granted rewards to his subordinates at his own expense, came to be widely recounted from the medieval period onward. The warrior culture that symbolized master-servant relationships through swords—the acts of bestowing, presenting, and dedicating swords—became deeply rooted as a Minamoto tradition through the conflicts of Tohoku.

The Significance of the Earlier and Later Three Years' Wars in Sword History

The Earlier and Later Three Years' Wars hold multiple important meanings in the history of the Japanese sword.

• These wars established the rise of the Minamoto warrior clan and paved the way for the establishment of the Kamakura shogunate, thus laying the foundation for the development of the entire warrior culture centered on the Japanese sword.
• Large-scale warfare in the provincial Tohoku region increased demand for practical swords and served as the impetus for refining the style of tachi capable of adapting to both mounted combat and hand-to-hand combat.
• The custom established in this era of "the head of the warrior clans rewarding retainers with swords" elevated the Japanese sword beyond a mere weapon to a social symbol. This legacy was transmitted from the late Heian period through the Kamakura and Muromachi periods into the Edo period, forming the cultural foundation by which the Japanese sword came to be called the "soul of the warrior."