The Ōnin-Bunmei Rebellion and the Sword Industry—The Historical Process of How Ten Years of Warfare Dispersed the Bizen Sword-Smith Groups and Its Impact on Sword Production

What Was the Ōnin-Bunmei Rebellion?

The Ōnin-Bunmei Rebellion, which began in Ōnin 1 (1467) and lasted until Bunmei 9 (1477), was a large-scale civil war that erupted when the succession problem of the Kanrei (Shogunal Manager) of the Muromachi Shogunate became entangled with the question of the Shogun's heir. The Eastern Army (Hosokawa faction) and the Western Army (Yamana faction) clashed with Kyoto as their main battlefield, and over approximately ten years of fighting, extensive areas of Kyoto's urban district were burned, and many cultural facilities, workshops, and artisan groups suffered devastating damage.

This rebellion was not merely a political dispute; it had serious repercussions for Japanese society, economy, and culture. For the sword industry in particular, it became a major turning point in what might be called the "golden age" of medieval Japanese swords—the era of the Kotō (Ancient Swords).

Bizen Province—The Greatest Medieval Sword Production Center

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

Bizen Province had geographical conditions suitable for sword production, with nearby deposits of iron sand and well-developed water transportation. It was also a transportation hub facing the Sanyōdō road and functioned as a supply center for the Shogunate and warrior clans throughout the country. Bizen swords before the Ōnin Rebellion were highly valued for their beautiful hamon (blade patterns—complex designs centered on chōji patterns) and superior jihada (grain patterns), and were prized as presentation gifts to the Shogunate and powerful daimyo.

Direct Effects of the Rebellion on Sword Production

The Ōnin Rebellion caused a sudden shift in Kyoto's demand for swords. While weapon consumption skyrocketed due to prolonged fighting, the rebellion disrupted distribution throughout the country, making the procurement of materials and sale of products difficult. Workshops around Kyoto suffered direct damage from the fighting, and many craftspeople were forced to evacuate.

Although the Bizen sword-smiths were geographically removed from the direct battlefield in Kyoto, they were not unaffected. Their patrons—influential temples and shrines, nobility, and Shogunate officials in Kyoto—fell into chaos, and orders plummeted. Furthermore, as the Shogunate's authority declined, public order deteriorated nationwide, and influential powers in various regions (kokujin local lords and shugo daimyo) increasingly sought to control sword production independently.

The Broad Dispersal of Sword-Smith Groups

Even after the Ōnin-Bunmei Rebellion ended, Japan's political turmoil continued. As local peasant uprisings (kokujin ikki) became frequent and the spirit of lower-ranking retainers overthrowing their superiors grew stronger, Bizen sword-smiths began moving to various regions in search of new patrons. This movement was not the emigration of isolated individuals, but rather organized migration of master-apprentice relationships and entire school groups.

Sword-smith groups that migrated to Mino Province (present-day southern Gifu Prefecture) later formed their own school, known as the "Mino tradition." Mino swords were characterized by pointed kissaki (blade tips) and sharp hamon, and they came to have high demand as practical battlefield swords during the Sengoku period. Seki (present-day Seki City, Gifu Prefecture) experienced rapid growth as a sword production center during this period, establishing the foundation for its role as a town of bladed tools that continues to the present day.

Evidence also suggests migration toward Sagami Province (present-day Kanagawa Prefecture), with some lineages helping pave the way for the later Shintō (New Sword) period. Additionally, sword-smith groups that migrated southward in response to invitations from powerful daimyo throughout Kyushu (such as the Shimazu and Ōtomo clans) became the catalyst for the birth of unique sword-forging traditions in various parts of Kyushu.

The Transformation of Bizen Sword-Smiths Who Remained

Sword-smith groups that remained in Bizen were also affected by the rebellion. To survive as their patronage system collapsed, they were forced to shift from high-quality, limited production to mass production of practical weapons. The precise chōji-based hamon patterns characteristic of pre-Ōnin Bizen swords gradually transformed into more simplified suguha (straight) and ko-midare (small irregular) patterns.

While this change is sometimes spoken of negatively as "the decline of Bizen," it can alternatively be understood as a rationalization in response to the demands of the age. In the market where large quantities of swords were needed throughout the Sengoku period, Bizen remained a major production center. Even within mass production, it maintained a certain level of quality while continuing to supply swords to warrior clans throughout the country.

The Diversification of Sword Culture Created by the Rebellion

After the Ōnin-Bunmei Rebellion, Japanese sword culture shifted from concentration in specific production centers to dispersal and diversification across various regions. This was not a simple decline, but rather became an opportunity for each region to develop its own distinctive sword culture. The reorganization of the various traditions—Mino, Sōshū, Yamato, and Yamashiro—and the formation of regional sword cultures with their own distinctive characteristics can be said to be products of this historically turbulent period.

The classification known as the "Gokaden (Five Traditions)"—Bizen, Yamashiro, Yamato, Sōshū, and Mino—as referred to by later sword scholars, was solidified through the political and social turmoil of this era. The chaos the rebellion brought to the sword industry ultimately became the source of geographical diversification and technological innovation in Japanese sword culture.