The Ōnin War and the Transformation of the Sword Industry

The Ōnin War — Kyoto's Devastation and the Collapse of the Sword Industry

In Ōnin 1 (1467), as the authority of the Muromachi shogunate declined sharply, a succession dispute over the shogun's heir prompted a confrontation between the Eastern army led by Hosokawa Katsumoto and the Western army led by Yamana Sōzen, sparking the Ōnin War. Kyoto, which became the battlefield, turned into a desolate wasteland after more than ten years of warfare, and most major temples and shrines save Kinkaku-ji were destroyed by fire.

This conflict had profound consequences for the Japanese sword industry. Sword smiths of the Yamashiro tradition concentrated in Kyoto, as well as master craftsmen from surrounding regions, fled to the provinces to escape the chaos. Sword culture had long been centered in Kyoto, but the Ōnin War marked a structural transformation whereby this center dispersed to multiple regions. The dispersal of sword smiths to the provinces ultimately brought about diversification of forging techniques and development of local sword cultures—a paradoxical result that enriched Japanese sword culture in the long term, despite its catastrophic origins.

The Emergence of Kazuuchi-mono — Mass-Produced Swords to Meet Massive Demand

With the Ōnin War, the practice of rule by the strong spread throughout Japan, and the curtain rose on the Sengoku era. An unprecedented scale of sword demand was born, as all armed forces from minor samurai and ashigaru (foot soldiers) to major daimyo required blades.

To meet this massive demand, a new category of swords called "kazuuchi-mono" (mass-produced swords) emerged. Unlike "jousaku" (fine works) carefully crafted in response to individual commissions, kazuuchi-mono were manufactured in standardized forms in large quantities. Though inferior in quality to fine works, they possessed adequate utility and could be supplied in large quantities at low prices—perfectly matching Sengoku demand.

The mass production system for kazuuchi-mono promoted a transition from individual master craftsmen engaged in artisanal forging to a division-of-labor workshop system employing multiple workers. This transformation can be described as the "industrialization" of the sword industry and interpreted as the embryonic form of modern manufacturing.

The Rise of Bizen — The Giant of Mass Production

The sword industry that surged most dramatically after the Ōnin War was that of Bizen Province (present-day Okayama). Numerous sword smiths concentrated in the Osafune region along the Yoshii River, and by leveraging favorable geographic conditions—easy access to quality iron sand, fuel (charcoal and wood), and water—they established a sword production system that achieved both quality and mass production.

Warring States period Bizen swords were termed "sue-bizen" (late Bizen). Compared to ancient Bizen or the Kamakura–Nanboku-chō periods, the artistic quality declined somewhat, yet they retained the characteristics of Bizen tradition in both hamon and jigane while being produced in large quantities as high-quality practical blades that circulated widely. The Sukesada school was the representative group of Bizen smiths of this era, with signatures such as "Yosozaemon'no'kami Sukesada" and "Genbei'no'kami Sukesada" appearing frequently. Today, these blades often circulate at relatively accessible prices in the collector market.

The Rise of Mino — The Pursuit of Functional Beauty and Combat Practicality

Mino Province (present-day Seki City, Gifu Prefecture) also developed rapidly after the Ōnin War as a sword production center. The Mino tradition began when Shizu Saburō Kanetsuji, one of Masamune's ten great disciples, transmitted Sagami techniques, and after the Ōnin War it developed distinctively during the Sengoku period as "Seki-kaji" (Seki smiths).

The characteristic feature of Mino tradition was the "togari-gunome" (pointed-semicircle) hamon, which combined high practicality and mass production capability. This hamon possessed high edge durability and resistance to breaking, conferring practical combat advantage even in intense warfare without blade damage. Master smiths such as Kanesada and Kanemoto became prominent, and Mino blades were favored by daimyo throughout the nation. In particular, Kanemoto's "Seki no Magoroku" was renowned for exceptional cutting power termed "futatsudō" (two bodies), with a legendary account of test cutting that severed two stacked torsos.

The Decline and Revival of Kyoto and the Yamashiro Tradition

The Ōnin War dealt the greatest blow to the Yamashiro tradition based in Kyoto. During the chaos, many smiths left Kyoto, and the refined and elegant style distinctive to Yamashiro tradition receded sharply for a time. However, as warfare subsided, smiths returned to Kyoto or new smiths migrated there, and the Yamashiro tradition experienced partial revival from the late Sengoku through the Azuchi-Momoyama period.

The fact that this era of chaos paradoxically brought about the development of sword culture across the provinces merits attention. The dispersal of sword smiths to the regions transmitted the advanced forging techniques that had previously concentrated in the capital to the provinces, laying the foundation for each region to nurture its own sword culture.

Implications for Collectors

Sue-bizen and sue-mino blades, compared to ancient Bizen or Ko-tō period works, circulate in greater quantities on the market and may sometimes be acquired at relatively accessible prices. As practical swords that survived the Sengoku era with historical value, and as an avenue to affordably appreciate the aesthetic qualities of the Bizen and Mino traditions respectively, they offer pathways as entry points for collectors interested in this period.