The Ōnin War Changed "The Main Role of Warfare"

The Ōnin War, which broke out in Ōnin 1 (1467), was an unprecedented civil strife that made Kyoto its battlefield for eleven years. One of the greatest changes this war brought to Japanese military history was the rise of the ashigaru (foot soldiers).

The battles of the Heian, Kamakura, and early Muromachi periods were centered on cavalry warfare with samurai as the main force. Mounted samurai wielding bows engaged in single combat, while foot soldiers played only a supplementary role. However, the prolonged and urban-type street warfare of the Ōnin War demonstrated the effectiveness of the highly mobile ashigaru. The ashigaru moved about with minimal equipment and engaged in arson, plundering, and guerrilla warfare.

This change fundamentally altered the demand structure for swords. Until then, custom-ordered swords (chūmonuchi), carefully crafted by individual swordsmiths over a long time, had been the mainstream for samurai. However, to equip ashigaru with swords required mass production, low cost, and quick manufacturing. This marked the beginning of full-scale mass production of quantity-produced swords (kazuuchitō).

The Ashigaru's Armament—What They Actually Carried

The armament of ashigaru can be partially reconstructed from military chronicles, illustrated scrolls, and excavated materials. The typical ashigaru equipment was as follows.

Primary Weapon: The spear was the most common. After the Ōnin War, the primary weapon of ashigaru units shifted from bows to spears. Spears were inexpensive to produce and required only simple training to use, making them ideal for equipping large ashigaru units.

The Sword as a Secondary Weapon: The swords worn by ashigaru held a different significance than those worn by samurai. They were primarily used as "a last resort when a spear broke or was lost" and for "taking an enemy's head (striking them down)." Therefore, practicality—not breaking, not rusting, and cutting effectively—took priority over artistic quality and refinement.

Sword Quality: The vast majority of swords used by ashigaru were quantity-produced swords. In the sword-forging regions of Bizen (Okayama Prefecture) and Mino (Gifu Prefecture), mass-production systems for quantity-produced swords were established after the Ōnin War. Unlike custom-ordered swords, which took a master craftsman several months to forge a single blade, quantity-produced swords were made in short timeframes at low cost through division of labor and simplified processes.

The Production System of Quantity-Produced Swords—The Workshop Revolution of Bizen and Mino

The most important production centers for quantity-produced swords were Bizen (the Seto Inland Sea region of Okayama Prefecture) and Mino (the Seki and Mino regions of Gifu Prefecture).

The Bizen Mass-Production System: The Bizen swordsmith groups, centered on Osafune, had produced large quantities of swords even before the Ōnin War. After the Ōnin War, they shifted from a system where individual master smiths produced small quantities of fine blades while passing down techniques through master-apprentice relationships, to a system where a master craftsman oversaw the process while multiple workers produced large quantities through division of labor.

The quantity-produced swords of Bizen were known as "Bizen-mono," and while they varied in quality, they maintained basic sharpness and durability. Because they could be supplied in large quantities, the Bizen sword-forging region became the largest supplier for the "complete sets of weapons" that warlords provided to ashigaru units.

The Mino Mass-Production System: The swordsmiths of Mino Province (present-day Seki, Gifu Prefecture and surrounding areas) became known as Seki smiths (Seki kaji). The swordsmiths of the Mino tradition were known for their excellent sharpness and distinctive style, particularly the three-cedar hamon, and even in the mass-production system, Mino swordsmiths achieved high production volumes. Mino swords were widely distributed to warlords in eastern Japan—the Takeda of Kai, the Uesugi of Echigo, and the Matsudaira of Mikawa.

The Ashigaru's Sword Acquisition Routes—Battlefield Plundering and Market Purchase

There were multiple ways ashigaru obtained swords.

Distribution from Warlords: There are confirmed examples of warlords ordering large quantities of quantity-produced swords from sword-forging regions and distributing them to ashigaru. This "weapons distribution" served both to secure the ashigaru's loyalty and to equip the military unit. To identify the owner, the warlord's family crest was engraved on, or a specific maker's mark was inscribed on, the distributed swords.

"Bundori" (War Spoils) on the Battlefield: "Bundori," the taking of enemy weapons when striking down an enemy on the battlefield, was an important source of income for ashigaru. If they struck down a renowned samurai, they could obtain a high-quality sword, and it was common to sell it for cash income.

Market Purchase: During the Sengoku period, merchants and markets dealing in swords developed throughout the country. If ashigaru were from rural backgrounds, they sometimes used supplementary farm income during peak seasons to purchase swords. Most swords circulating in the market were quantity-produced swords or used swords in poor condition.

Ashigaru Armament and Structural Changes in the Sword Industry

The rise of ashigaru and the spread of quantity-produced swords fundamentally changed the structure of the Japanese sword industry.

The Beginning of Polarization: After the Ōnin War, the sword market clearly divided into two poles: "fine swords for warlords and samurai (custom-ordered)" and "quantity-produced swords for ashigaru and peasant soldiers." This polarization can be seen as the prototype of the modern distinction between "art swords" and "practical items" in the sword market today.

Specialization Among Swordsmiths: In the mass-production system, there was a tendency toward specialization in various processes, including the process of forging the blade using tamahagane as material, the hardening process, and the polishing process. This was also the period when the traditional system in which one swordsmith handled all processes began to coexist with the mass-production system enabled by specialization.

Expansion of Sword Distribution Networks: Mass-produced quantity swords circulated widely through wholesalers and sword markets throughout the country. "Sword logistics" became fully developed as warlords placed large orders with sword-forging regions in distant areas and had them transported by sea and land routes. This distribution system became the predecessor of the sword merchants and sword wholesaler system of the Edo period.

The existence of ashigaru transformed swords from "the possession of a small warrior elite" to "something required by the many who participated in warfare." While this change, which might be called a democratization, promoted mass production in the Japanese sword industry, it also had the paradoxical effect of making the traditional swordsmith culture that produced fine works and masterpieces stand out as "something special."