The Jisho-Juei War (1180–1185) and Sword Supply: The Surge in Sword Demand and Craftsmen Migration During the Prolonged Genpei War

The Jisho-Juei Rebellion: Japan's First Nationwide Prolonged Civil War

The "Jisho-Juei Rebellion" (Genpei War), which began in 1180 when various Minamoto clans raised armies in response to the imperial order of Prince Mochihito, and which lasted six years against the Heike political regime supporting Emperor Antoku, occupies a unique position in Japanese history. It was the first instance where battlefields expanded across the entire archipelago, from the northeast (Ou region) to the southwest (Kyushu and Dan-no-ura), and had no precedent in the duration of combat or geographical scope.

The influence this prolonged civil war exerted on the history of Japanese swords is immeasurable. Earlier large-scale conflicts such as the Shohei-Tengyō Rebellion (939–941) and the Hōgen and Heiji Rebellions (1156 and 1159) were all brief and geographically limited in scope. By contrast, the six-year Jisho-Juei period created a "weapons supply problem" of an entirely different scale in terms of sustained combat, troop replenishment, and weapon attrition.

Pre-War Sword Production Systems: Inventory and Production Capacity Limits

Sword production in the late Heian period was primarily handled by sword-maker communities in Yamashiro, Yamato, and Bizen. Smiths of this era were often placed under the protection of temples, shrines, or aristocrats within their estates, functioning as "official sword-makers" for specific nobles, warrior clans, and religious institutions. Rather than large-scale speculative production, the fundamental model was small-scale made-to-order manufacturing.

Historical records from the late Heian period contain few clear accounts of how many swords a single smith could produce annually, but compared with Edo-period regulations (the modern system limiting officially recognized smiths to 24 swords per year), the hand-craft production methods of the time suggest that an individual smiths could produce only several to a dozen or so swords per year at maximum.

Before 1180, even if all the sword-makers in Yamashiro, Yamato, and Bizen were combined, their existing inventory and immediate production capacity were absolutely insufficient to support a nationwide prolonged war.

The Explosion of Demand: From the Uprising to Ichinotani (1180–1184)

After Prince Mochihito's imperial order was transmitted to the provinces in 1180, various Minamoto-affiliated warrior bands successively raised arms. Yoritomo united powerful families in Izu and Sagami, while Yoshinaka marched southward through Shinano and Echigo into the Hokuriku region. As warrior bands across the country armed themselves, demand for swords exploded.

The structure of demand divided into three layers.

• First layer "strengthening the armament of existing warriors (local samurai and prospective housemen)": Samurai from rural Eastern Japan, for whom iron tools were the primary metal products in daily use, now needed to procure swords, armor, and bows for participation in battles
• Second layer "initial supply to newly mobilized warrior bands": The distribution of weapons to the retainers and followers of prominent housemen such as the Chiba, Miura, and Hōjō clans who participated in Yoritomo's banner-raising
• Third layer "replacement demand as consumables": The need to replace swords damaged by breakage, bending, and chipped blades in combat

The third layer was especially critical in prolonged warfare. The major battles conducted over the six-year period from 1180 to 1185 (Fujikawa, Kurikara Pass, Ichinotani, Yashima, and Dan-no-ura) collectively involved several thousand to over ten thousand participants. The number of swords that suffered chipped blades or damage in these battles must have been enormous, creating constant demand for either "repair" or "new procurement."

The Migration of Sword-Makers: From Yamashiro and Yamato to Eastern Japan and Kyushu

The most revolutionary change the Jisho-Juei Rebellion brought to sword supply was "geographical migration of sword-makers." Previously concentrated in the Kyoto region (Yamashiro and Yamato) and Osafune in Bizen, sword-makers dispersed and relocated to various regions across the country, drawn by wartime demand.

Historical records show that multiple sword-makers were invited to Kamakura, which became the base of the Minamoto, after Yoritomo's establishment of his government in 1185. "Shintogo Kunimitsu (shintougokunimitsu)," regarded as the founder of Soshu (Sagami Province) sword-makers, has dated works from the late Kamakura period, 1293 onwards (Yonin 1), showing a time gap of about 100 years from the Jisho-Juei era. The recruitment of sword-makers that formed the foundation of the Soshu tradition is considered to have occurred during the time of Hōjō Tokiyori (the fifth shikken, mid-13th century), and cannot be directly linked to the Jisho-Juei Rebellion.

In Kyushu, the base of the Heike, local Kyushu sword-makers (the Namihira school, centered in Satsuma) responded to the military needs of the Heike. Because Kyushu and Western Japan remained a primary battleground until Dan-no-ura in 1185, sword-maker groups from Satsuma, Bungo, and Chikuzen came to be recorded in historical documents.

In Eastern Japan, with the establishment of Yoritomo's houseman system in the 1180s, examples exist of smiths invited as "official sword-makers" of prominent housemen and settling in Sagami, Musashi, and Hitachi. These movements are considered to have later formed the foundation of the "Soshu tradition."

The Rise of Bizen Sword-Makers: Responding to Surging Demand and Mass Production

The sword-maker community around Osafune in Bizen Province (present-day Okayama Prefecture) experienced the most dramatic development during this era. The Bizen Osafune sword-maker group had already established its reputation by the late Heian period, but the surge in demand through the Jisho-Juei Rebellion accelerated their production scale and technical advancement.

The geographical reasons for Bizen Osafune's prosperity are clear. Located facing the Seto Inland Sea maritime route, they could rapidly transport swords to various parts of western Japan via the Sanyo road and sea routes. Additionally, the ability to conduct iron-sand mining and iron-smelting using water power from the Yoshii River basin contributed to reducing production costs.

The concentration of Bizen sword-makers confirming from literature and excavated materials expanded rapidly after the Jisho-Juei Rebellion. The lineage of sword-makers such as "Kagetatsu (kagetatsu)" who were active in the Jisho-Juei period represents the foundation-forming stage of this era. Note that "Kagemitsu (kagemitsu)" was a sword-maker of the late Kamakura period (dated works from 1306–1334) and "Kanemitsu (kanemitsu)" was a sword-maker of the Northern and Southern Courts period, with a time gap of approximately 120–150 years from the Jisho-Juei era. The founder of the Osafune school is traced to Mitsutada (late Heian to early Kamakura).

Technical Influences: Changes in Sword Form Born from Actual Combat Demands

The technical influence the Jisho-Juei Rebellion exerted on sword form must not be overlooked. Tachi of the early Heian period were primarily intended for court ceremonies and the personal protection of nobility, with beauty and symbolic significance emphasized. However, through prolonged actual combat, demands for practicality—"never breaking, bending, or chipping"—grew stronger.

Swords of this era (tachi of the early Kamakura period) display the following characteristics.

• A robust, powerful form
• A transitional change from slender form to the "inokoshi-kissaki" (boar-neck tip)
• Stabilization of choji (choji) ranged blade patterns

These were not merely changes in aesthetic sensibility but can be interpreted as the result of feedback from actual combat experience influencing the technical choices of sword-makers.

Of particular note is the change in the "curve (sori)" of swords. There is a visible trend from the waist-curve reflection of the early Heian period (reflection located near the sword's center of gravity) to mid- and forward-reflection tendencies in the Kamakura period. One theory suggests this change reflects a tactical shift from "slashing downward from horseback" to an emphasis on "cutting in foot combat."

Post-War Administration: The Yoritomo Regime and the Institutionalization of Swords

After 1185 and Dan-no-ura, the institutional construction of Minamoto Yoritomo's Kamakura bakufu brought significant changes to the social positioning of swords.

The system of "hairyoto" (swords given as rewards) to housemen was established, and swords came to function as political symbols that made visible the hierarchy of samurai and master-servant relationships. Records remain of Yoritomo himself commanding multiple master craftsmen to forge swords, which were then directly bestowed upon his housemen.

This practice of "political communication through swords" became the origin of later "presentation swords and bestowed swords" culture among the Muromachi shogunate and Sengoku daimyo, and became the starting point of a long process by which the Japanese sword transcended being merely a weapon to become a "symbol of power and order."

The Jisho-Juei Rebellion represented a dual turning point in the history of the Japanese sword: both a "quantitative explosion of demand" and a "geographical reorganization of supply systems." Without this era, the large-scale sword-maker concentrations like Bizen Osafune, the technical innovations of Soshu sword-makers, and the sword culture of Kamakura samurai society would undoubtedly have taken entirely different forms.