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

What Was the Ōnin-Bunmei Rebellion

The Ōnin-Bunmei Rebellion, which began in Ōnin 1 (1467) and continued until Bunmei 9 (1477), was a large-scale civil war that erupted from the entanglement of the problem of succession to the post of Kanrei of the Muromachi shogunate and the problem of succession to the shogun. The Eastern forces (Hosokawa faction) and Western forces (Yamana faction) clashed with Kyoto as the primary battleground, and over approximately ten years of fighting, much of Kyoto's urban area was extensively burned, and many cultural facilities, workshops, and artisan communities received devastating damage.

This warfare was not merely political internal strife but had profound impacts on Japanese society, economy, and culture. In particular, for the sword industry, it became a major turning point in what could be called the golden age of medieval Japanese swords—the Kotō period.

Bizen Province—The Largest Medieval Sword Production Center

Before the Ōnin Rebellion, Bizen Province (present-day southeastern Okayama Prefecture) was known as Japan's largest sword production center. Bizen had developed a distinctive forging culture known by the name "Bizen blade," and a major settlement of sword masters had formed centered on Osafune. Multiple schools such as the Osafune school, the Ichimonji school, the Fukuoka Ichimonji school, and the Yoshii school coexisted and competed with each other in technique while producing large quantities of high-quality swords.

Bizen Province had geographical conditions suited to sword production, with nearby deposits of iron sand and developed water transportation. It also functioned as a strategic point of transportation facing the Sanyōdō and as a supply base for the shogunate and warrior families throughout the land. Before the Ōnin Rebellion, Bizen blades were highly regarded for their beautiful hamon (a complex pattern centered on the choji-midare) and superior jihada, and were valued as offerings to the shogunate and powerful daimyo.

Direct Impact of the Rebellion on Sword Production

The Ōnin Rebellion drastically changed sword demand in Kyoto. While weapon consumption skyrocketed due to prolonged fighting, distribution in various regions stagnated due to the warfare, making it difficult to procure materials and sell products. Workshops around Kyoto suffered direct damage from the fires of war, and many craftspeople were forced to evacuate.

The Bizen sword makers, though they were removed from Kyoto which was the direct battlefield, could not remain untouched. The powerful temples, shrines, nobles, and shogunate-related figures in Kyoto who had been patrons fell into chaos, and orders declined dramatically. Furthermore, as the shogunate's authority declined, security deteriorated nationwide, and powerful figures in various regions (kokujin lords and shugo daimyo) increasingly moved to take direct control of sword production.

The Widespread Dispersal of Sword-Making Communities

Even after the Ōnin-Bunmei Rebellion subsided, Japan's political turmoil continued. As kokujin uprisings occurred frequently and the spirit of gekokujō strengthened, Bizen sword makers began moving to various regions in search of new patrons. This movement was not individual migrations but, according to accounts, organized movement of master-apprentice groups and fellow-school communities.

• Seki in Mino Province (present-day Gifu Prefecture, southern Gifu) underwent rapid growth as a sword production center during this period and established the foundation for the blade-producing town that continues to the present day. However, the "Mino tradition" itself had already been established before the Ōnin Rebellion, founded by Shizu Saburō Kaneuji from Yamato (who flourished during the Kemmu period) and Kaneshige and others who migrated from Echizen, who created it by fusing the Sōshū and Yamato traditions. While the migration of Bizen sword makers contributed to the expansion of sword production in Mino, it was not the Bizen sword-making community that established the Mino tradition. Mino blades are characterized by a pointed kissaki and sharp hamon, and would come to have high demand as practical combat blades during the Sengoku period.
• A flow toward the Sagami region (present-day Kanagawa Prefecture) has also been documented, and there were lineages that created a pathway to what would become the later Shinto period.
• Some sword-making communities also moved south in response to invitations from powerful daimyo throughout Kyushu (such as Shimazu and Ōtomo), becoming the catalyst for the birth of distinctive sword-forging traditions throughout Kyushu.

The Transformation of Bizen Sword Makers Who Remained

The sword-making communities that remained in Bizen were not untouched by the effects of the rebellion. To survive amid the collapse of the patronage system, they were forced to shift from high-quality, small-scale production to large-scale production of practical weapons. The refined choji-midare hamon that Bizen blades had possessed before Ōnin gradually changed to more simplified suguha and ko-midare patterns.

While this change is sometimes spoken of negatively as "the decline of Bizen," it can also be understood as a rationalization in response to the demands of the age. Throughout the Sengoku period, in a market where large quantities of swords were needed, Bizen remained a major production center. While maintaining a certain level of quality even in mass production, it continued to supply swords to warrior families throughout the country.

The Diversification of Sword Culture Born from the Rebellion

With the Ōnin-Bunmei Rebellion as a watershed, Japanese sword culture transformed from concentration in specific production centers to dispersal and diversification across various regions. This was not simply a decline but also became an opportunity for each region to develop its own distinctive sword culture. The reorganization of each tradition such as Mino, Sōshū, Yamato, and Yamashiro, and the formation of sword culture with distinctive regional characteristics, can be said to be the products of this period of historical upheaval.

The classification that later sword researchers refer to as the "Five Traditions" (Go-ka-den)—Bizen, Yamashiro, Yamato, Sōshū, and Mino—solidified through the political and social turmoil of this era. The confusion that the rebellion brought to the sword industry ultimately became a source of geographic diversification and technological innovation in Japanese sword culture.