The Onin-Bunmei War and the Japanese Sword Industry: How a Decade of Conflict Dispersed Bizen Swordsmiths

The Ōnin-Bunmei Uprising: What It Was

Beginning in 1467 (the first year of Ōnin) and continuing until 1477 (the ninth year of Bunmei), the Ōnin-Bunmei Uprising was a large-scale civil war that erupted from the entanglement of succession disputes over the kanrei (shogunate administrator) position and the question of the shogun's heir. The Eastern Army (Hosokawa faction) and Western Army (Yamana faction) clashed with Kyoto as their primary battlefield, and over approximately ten years of fighting, vast areas of Kyoto's urban center were burned, and many cultural facilities, workshops, and artisan communities suffered devastating damage.

This uprising was not merely a political conflict, but had profound impacts on Japanese society, economy, and culture. For the blade-making industry in particular, it marked a major turning point in what could be called the golden age of medieval nihonto—the era of the "old swords."

Bizen Province—The Medieval Era's Greatest Sword Production Center

Before the Ōnin Uprising, Bizen Province (present-day southeastern Okayama Prefecture) was known as Japan's largest center for sword production. Bizen had developed a distinctive blacksmithing culture known as "Bizen swords," and around the town of Osafune, a major community of master swordsmiths had formed. Multiple schools—including the Osafune school, Ichimonji school, Fukuoka Ichimonji school, and Yoshii school—coexisted and competed with one another in technique while producing large quantities of high-quality swords.

Bizen Province had geographical advantages for sword production: sources of iron sand were nearby, and waterborne transportation was well developed. It was also positioned on a major transportation route facing the Sanyo Road and functioned as a supply center for the shogunate and samurai clans throughout the land. Before the Ōnin Uprising, Bizen swords were highly esteemed for their beautiful hamon (blade patterns featuring intricate designs centered on choji-midare) and excellent core steel (jigane), and were frequently presented as tribute to the shogunate and powerful daimyo.

The Uprising's Direct Impact on Sword Production

The Ōnin Uprising dramatically shifted the demand for swords in Kyoto. While prolonged fighting led to a surge in weapons consumption, the chaos of war disrupted trade routes throughout the land, making it difficult to procure materials and sell finished products. Workshops around Kyoto suffered direct damage from the fighting, forcing many artisans to flee.

Although Bizen's swordsmiths were geographically removed from the direct fighting in Kyoto, they were not unaffected. Their patrons—prominent Kyoto temples, shrines, nobility, and shogunate officials—fell into chaos, and orders plummeted. Moreover, as the shogunate's authority declined, security throughout the land deteriorated, and local strongmen—kokujin landlords and shugo daimyo—began moving to develop their own sword production capabilities.

The Dispersal of Swordsmith Communities Across Wider Territory

Even after the Ōnin-Bunmei Uprising subsided, political turmoil continued in Japan. As peasant uprisings (kokujin ikki) became frequent and the spirit of gekokujō (the lower overthrowing the upper) grew stronger, Bizen's swordsmiths began migrating to various regions in search of new patrons. This was not merely individual or small-scale migration, but rather organized movement of entire schools and master-apprentice lineages.

Swordsmith communities that migrated to Mino Province (present-day southern Gifu Prefecture) later formed their own distinctive school, known as the "Mino tradition." Mino swords were characterized by pointed kissaki (tips) and sharp hamon and became highly sought-after as practical blades during the Sengoku period. Seki (present-day Seki City in Gifu Prefecture) rapidly grew as a sword production center during this period and laid the foundation for its modern status as Japan's cutlery capital.

Migration to the Sagami region (present-day Kanagawa Prefecture) is also documented, and some lineages that emerged played a role in establishing the foundations of the later Shintō (new sword) period. Additionally, swordsmith communities responded to invitations from powerful daimyo in various parts of Kyushu—such as the Shimazu and Ōtomo—and their southern migration became the catalyst for the emergence of distinctive katanakaji (sword-making) traditions throughout Kyushu.

The Transformation of Bizen Swordsmiths Who Remained

Swordsmith communities that remained in Bizen were also not immune to the effects of the uprising. To survive in a collapsed patronage system, they were forced to shift from high-quality, limited production to mass production of practical weapons. The intricate choji-midare hamon of Bizen swords before Ōnin gave way to simpler, more streamlined patterns—straight blades and minor irregularities.

This change is sometimes described negatively as "the decline of Bizen," but it can also be understood as a rational response to the demands of the era. Throughout the Sengoku period, when large quantities of swords were needed, Bizen remained a major production center. Even while mass-producing, it maintained a certain standard of quality and continued supplying swords to samurai clans throughout the nation.

The Diversification of Sword Culture Born from the Uprising

Beginning with the Ōnin-Bunmei Uprising, Japanese sword culture shifted from concentration in specific production centers to dispersal and diversification across the country. This was not simply a decline, but rather an opportunity for each region to develop its own distinctive sword culture. The reorganization of the various traditions—Mino, Sagami, Yamato, and Yamashiro—and the formation of regionally distinctive sword cultures were products of this turbulent historical period.

The classification of the "Five Traditions" (Go Kaiden)—Bizen, Yamashiro, Yamato, Sagami, and Mino—that later sword scholars identified became established only after passing through the political and social upheaval of this era. The disruption the uprising brought to the sword-making industry ultimately became a wellspring for the geographic diversification and technical innovation of Japanese sword culture.