The Onin War (1467–1477) and Japanese Swords: How the Kyoto Conflict Reshaped Bizen and Yamato Swordsmiths

The Ōnin War—A Major Watershed in Sword History

The Ōnin War, which began in 1467 (the first year of Ōnin), was a large-scale civil conflict lasting over a decade, centered mainly in Kyoto and triggered by succession disputes within the Ashikaga shogunate. It drew in regional daimyo from across the country. While this warfare marked a watershed in Japanese politics, culture, and economy, it equally represents an extremely crucial turning point in the history of swords.

Before the Ōnin War, Kyoto was the center of Japanese sword culture. A market for high-quality swords existed to meet the demands of the court nobility, temples and shrines, and the shogunate, and swordsmiths from the Yamato tradition (workshops in the five home provinces) flourished. However, eleven years of warfare burned Kyoto to the ground and destroyed the very urban infrastructure that had supported the circulation and appreciation culture of swords.

The Collapse of Kyoto's Sword Culture

Kyoto, which became the battleground of the Ōnin War, saw vast areas of the Kamigyō and Shimogyō districts destroyed by fire. Many sword merchant shops, swordsmith workshops, and armories of the nobility and temples and shrines burned. The network of the upper classes that had supported sword appreciation alongside the tea ceremony and Noh theater collapsed.

The culture of sword "connoisseurship"—the system of polishing, appraisal, and certification papers maintained by the Honami family—suffered major damage in this warfare. The Honami family evacuated temporarily to the countryside to avoid the flames and was forced to reduce its activities in Kyoto. With the mechanisms for evaluating and distributing high-quality "upper-grade swords" broken, demand began to shift toward mass-produced goods.

The Bizen Smiths' "War-Demand Boom"

The Ōnin War and the subsequent Sengoku period explosively expanded sword demand. The primary beneficiaries were the swordsmith communities of Bizen (present-day eastern Okayama), particularly those of the Osafune lineage, which had enjoyed high reputation as "Bizen-mono" throughout the Kamakura and Muromachi periods.

After the Ōnin War, however, the Bizen workshops made a major shift toward mass-production systems. The reason was simple: responding to demand for "swords consumed in vast quantities on the battlefield." Regional daimyo and territorial lords began placing orders for dozens to hundreds of blades at a time to equip their troops.

Swords from this period are collectively called "Sue-bizen" (late Bizen), and compared to earlier work like the Ichimonji and Ko-bizen styles, they are often considered qualitatively inferior. Certainly, many individual blades produced by these smiths fell short of works by named masters of earlier times. However, given that the market demand of the era prioritized "durability and quantity over beauty," this was a rational response.

Among Sue-bizen swordsmiths, capable masters such as Sukesada, Tadamitsu, and Kiyomitsu produced excellent work, and their superior blades remain highly regarded in later periods. The Osafune swordsmith village continued to prosper for some time after the Ōnin War and played an important role as a weapons supplier during the Sengoku period.

Yamato Swordsmiths—Decline and Transformation of the Five Schools

The impact of the Ōnin War extended to Yamato (present-day Nara Prefecture), a sword-producing region comparable to Bizen. Yamato was one of the Five Schools of sword-making, with five lineages of smiths active—Shizu, Tegaki, Taima, Senjuin, and Hoshshō—but it entered rapid decline after the Ōnin War.

One reason was that Yamato swordsmiths operated under the patronage of temple and shrine powers such as Kōfuku-ji and Kasuga Taisha. The Ōnin War destabilized the financial foundations of these institutions, reducing their orders and support for swordsmiths. Additionally, Yamato lacked the geographical and organizational conditions to easily establish mass-production systems like Bizen, making it difficult to meet large wartime orders.

Some Yamato smiths relocated to various regions to escape the turmoil and established local schools in their new homes. This "dispersal of the Yamato tradition" was, paradoxically, a phenomenon caused by population movement triggered by the Ōnin War, and it eventually led to the diversity of regional sword cultures in later periods.

Changes in Sword Distribution—From Nobility to Samurai and Merchants

The Ōnin War fundamentally transformed the structure of sword distribution. Previously, the dominant pattern was for "upper-class consumers" such as the nobility, temples and shrines, and the shogunate to commission and purchase expensive upper-grade swords. But after the Ōnin War, middle and lower-ranking samurai and merchants began seeking swords as "practical tools," and the market expanded to the broader population.

This transformation, which might be called the democratization of the sword market, activated commercial sword distribution while intensifying price competition and heralding an era emphasizing quantity over quality. Some swordsmiths differentiated themselves by adhering to "signatures"—carving the smith's name on the tang—using marked blades as a quality assurance signal.

What the Ōnin War Left Behind

The Ōnin War is positioned in Japanese sword history as "the turning point from the golden age of old swords to mass-produced blades of the Sengoku period." The ancient production centers of Bizen and Yamato underwent restructuring, laying the groundwork for the rise of new production centers such as Satsuma, Echizen, Owari, and Suruga in later periods.

Many celebrated swords were lost in the warfare of this era, and the rarity of surviving swords from the mid-Muromachi period and earlier is not unrelated to these flames. The hundred years spanning the Ōnin War and the Sengoku period that followed represent an era in sword history marked by the most intense consumption and most active production of swords.