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

The Ōnin War — A Major Watershed in the History of Japanese Swords

The Ōnin War, which began in 1467 (Ōnin 1), was a large-scale civil conflict triggered by a succession dispute within the Ashikaga shogun family, involving feudal lords throughout the country and unfolding over more than 10 years, primarily centered on Kyoto. While this conflict became a watershed in Japan's politics, culture, and economy, it is positioned as an extremely important turning point in the history of Japanese swords as well.

Before the Ōnin War, Kyoto was the center of Japanese sword culture. There was a market for high-quality swords that met the demands of the imperial court, temples and shrines, and the shogunate, and swordsmiths from the five provinces of Kinai (Yamato-den workshops) flourished. However, the conflict spanning 11 years burned Kyoto to ashes and destroyed the very urban infrastructure that supported the distribution and appreciation culture of Japanese swords.

The impact brought about by the war was not merely temporary; it held deeper significance than just "Kyoto's devastation" in that it changed the entire framework of how swords would be made, into whose hands they would pass, and how they would be evaluated throughout the subsequent Sengoku period. Even today, when swords from the Ōnin War period through the Sengoku period are handled as antiques and artworks, they are often evaluated in light of this shift.

The Destruction of Kyoto's Sword Culture

In Kyoto, which became the battlefield of the Ōnin War, vast areas of Kamigyo and Shimogyo were burned. Many workshops of sword merchants and swordsmiths, as well as armor stores belonging to the imperial court and temples and shrines, were destroyed. The network of upper-class society that had supported sword appreciation alongside tea ceremony and Noh theater collapsed.

The "connoisseurship" culture of swords—the system of polishing, authentication, and certification that the Honami family had managed—suffered a major blow in this conflict. The Honami family fled to the countryside to escape the war and had to scale back their activities in Kyoto. With the mechanism for evaluating and distributing high-quality swords no longer functioning, the groundwork was laid for demand to shift toward mass-produced items.

What was lost during this period was not only physical facilities like workshops and storehouses. The invisible foundations—the eye for authentication and technical knowledge accumulated over generations, and the personal networks connecting patrons with swordsmiths—were also severed. It took a long time before Kyoto's sword culture was rebuilt after the war, and this gap in time resulted in giving opportunities for regional groups of swordsmiths to flourish.

The 'War Demand Bubble' of Bizen Swordsmiths

The Ōnin War and the subsequent Sengoku period caused sword demand to expand explosively. The swordsmith group of Okayama and Bizen (present-day eastern Okayama Prefecture) benefited the most.

The workshops of the Bizen-den and Osafune schools, which had enjoyed high reputation as "Bizen swords" throughout the Kamakura and Muromachi periods, made a major shift toward mass production after the Ōnin War. The reason was simple: to meet the demand for "swords consumed in massive quantities on the battlefield." As feudal lords and regional leaders throughout the country supplied weapons to their soldiers, orders increased in units of dozens to hundreds of swords.

Swords from this period are collectively called "sue-Bizen," and they are often evaluated as being qualitatively inferior compared to Ichimonji swords from the mid-Kamakura period and old Bizen. Certainly, the individual quality of many swords was inferior compared to works by named masters. However, considering that demand at the time sought "durability and quantity over beauty," this was a rational response.

Among sue-Bizen swordsmiths, there were also skilled craftsmen such as Sukesada, Tadamitsu, and Kiyomitsu, and their finest works were highly regarded even in later generations. The swordsmith village of Osafune continued to prosper for a while after the Ōnin War and played an important role as a weapons supply center during the Sengoku period.

The reason Bizen was able to shift to mass production was not only because of its geography, which made it easy to secure high-quality iron sand and charcoal for fuel, but also because its favorable transportation conditions via waterways made it easy to distribute finished products to various regions. These strengths in both production and distribution supported the system that could meet the expanded demand during the period of conflict.

Yamato Swordsmiths — The Decline and Transformation of the Five Schools

The impact of the Ōnin War also reached Yamato (present-day Nara Prefecture), a major sword production area alongside Bizen. Yamato was one of the Five Schools, and the following five schools of swordsmiths were active there, but they rapidly declined after the Ōnin War.

• Senjuin
• Tegaki
• Taima
• Hōshō
• Shirigake

One reason was that Yamato swordsmiths operated under the patronage of temple and shrine powers such as Kofuku-ji Temple and Kasuga Taisha. The Ōnin War also shook the financial foundations of temples and shrines, reducing orders and support for swordsmiths. Additionally, Yamato faced geographical and organizational conditions that made it difficult to establish mass production systems compared to Bizen, and thus struggled to meet the massive orders for war supplies.

Some Yamato-origin swordsmiths migrated to various regions to escape the warfare and established regional schools in their new homes. This "seeding of Yamato-den," ironically, was a phenomenon caused by the population movement triggered by the Ōnin War, and it led to the later diversity of regional sword culture.

While dependence on a single patron such as temples and shrines provided stable demand during peacetime, it also carried the fragility of losing orders entirely when the patron itself suffered damage. While Bizen survived supported by multiple customer bases including warrior clans and merchants, Yamato is thought to have experienced a greater degree of decline due to this structural difference.

The Transformation of Sword Distribution — From the Imperial Court to Warriors and Merchants

The Ōnin War greatly changed the distribution structure of swords. Previously, the mainstream structure was "upper-class consumers" such as the imperial court, temples and shrines, and the shogunate ordering and purchasing expensive high-quality swords. However, after the Ōnin War, middle and lower-ranking warriors and merchants began seeking swords as "practical tools," expanding the base of the market.

This change, which could be called a democratization of the sword market, activated the commercial distribution of swords while intensifying price competition and heralding the arrival of an era of quantity over quality. Some swordsmiths insisted on signatures (carving the swordsmith's name on the nakago) as a means of differentiation, and came to utilize their signatures as a signal of quality assurance.

While having a signature itself did not guarantee quality at that time, it was important that it functioned as a clue for patrons to assess a swordsmith's skill and reputation. The concept of "selecting by signature," which became established during this era, also relates to how sword authentication and evaluation developed in later generations.

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 the mass-produced swords of the Sengoku period." The traditional production areas of Bizen and Yamato were reorganized, and the groundwork was laid during this era for emerging production areas such as Satsuma, Echizen, Owari, and Suruga to later rise to prominence.

Moreover, many renowned swords were lost in the warfare of this era, and the rarity of existing swords from before the mid-Muromachi period is not unrelated to this warfare. The Ōnin War and the subsequent 100 years of the Sengoku period are recorded in sword history as the era when sword consumption was most intense and production most active.

Things to Know When Viewing Sue-Bizen and Yamato-den Swords

Today, when appreciating and owning swords made around the time of the Ōnin War through the Sengoku period, having several perspectives deepens understanding.

• Individual variation in quality: Works by sue-Bizen and Yamato-origin swordsmiths who moved to provincial areas mixed signed and unsigned pieces even within the same period, and there was considerable variation in the quality of individual works. Even though these were works from an era that prioritized quantity, the finest works by swordsmiths such as Sukesada, Tadamitsu, and Kiyomitsu, whose reputation continued through later generations, have been treated as exceptional.
• Certificates of authentication: In objectively grasping the provenance and style of swords from this era, the existence of certificates issued by official authentication institutions is an important clue. Certificates from the NBTHK (Japanese Art Sword Preservation Society) provide third-party expert assessment regarding the attribution of swordsmith and period, and serve as a reference when handling swords with the context of around the Ōnin War.
• Condition of preservation: The condition of the blade—the presence or absence of rust and edge damage, the condition of polishing, and the preservation state of the fittings and shirasaya—are also points to check in conjunction with the historical context.

Since any sword that exists today has survived a long passage of time, each one has a corresponding provenance, and understanding it including that provenance leads to knowing the historical turning point of the Ōnin War through the sword itself.