From Naginata to Yari: Why the Spear Replaced the Halberd as the Primary Infantry Weapon in Early Sengoku Japan

The Golden Age of the Naginata—Principal Weapon from the Late Heian through the Kamakura and Nanboku-chō Periods

The naginata shone as the star of Japanese battlefields from the late Heian period through the Nanboku-chō period (14th century). The naginata, with its curved blade affixed to a long shaft, demonstrated its power as a slashing weapon, targeting the legs of mounted warriors and sweeping across a wide area through rotating body movements.

Military chronicles depicting the Genpei War frequently feature dramatic single combat scenes involving the naginata, and as the legend of Benkei gathering a thousand swords on a bridge demonstrates, it was recognized by the common people as a representative weapon of that era.

In the Kamakura period, naginata technique was included in samurai training curricula, and by the turbulent Nanboku-chō period, tactics had been established where groups of infantry warriors would charge wielding naginata. Large naginata from this era often exceeded 1 meter in blade length and were sophisticated weapons requiring considerable physical strength and skill.

The naginata shaft was made from hard wood such as oak, and the blade had a distinctive shape that widened toward the tip. This shape allowed practitioners to generate powerful strikes by leveraging centrifugal force during sweeping motions. Conversely, wielding it required considerable core strength and proficiency, and even among the limited samurai class, those who mastered naginata technique were held in high regard.

The naginata excelled in the following combat situations.

• Anti-cavalry warfare targeting the legs of mounted warriors
• Defensive combat in confined spaces such as castle corridors and temple hallways
• Maintaining distance in chaotic combat against multiple opponents

The Mid-Muromachi Turning Point—Why Did the Spear Rise to Prominence?

After the Ōnin War (1467–1477), signs of a change in dominance on the battlefield became clear. Multiple factors contributed to this transformation.

Factor 1: Changes in Group Tactics

The largest factor in this shift was the appearance of large numbers of light-armed infantry called ashigaru who were not of samurai origin. It was difficult to train ashigaru, who lacked formal martial training, to master the technically demanding naginata technique, whereas the spear, operated through simpler thrusting motions, could be deployed in actual combat after only brief training.

Factor 2: Manufacturing Cost and Availability of Spears

Manufacturing naginata required advanced technique to forge heavily curved blades, whereas spearheads with triangular cross-sections could be mass-produced in relatively simple forms. In the mass mobilization system of the Sengoku period, the ability to mass-produce weapons was strategically critical, and spears demonstrated clear superiority.

Factor 3: Efficiency of Long-Shafted Weapons

The long-shafted spear was optimized for simultaneous assaults in close formations. Tactics involving densely massed spears called yarisbusuma were effective even against mounted warriors and, as group tactics not dependent on individual skill, were actively adopted by Sengoku daimyo.

However, the shift from naginata to spear did not occur overnight. In large-scale group battles on open plains, coordinated massed spear assaults demonstrated overwhelming efficiency. Conversely, in confined corridors of castles and temples and in localized combat prone to chaos, the naginata's ability to sweep and control wide distances remained effective, and both weapons coexisted for some time depending on their application.

The Naginata's Survival Strategy—Modification and Change in Use

Although the naginata yielded its starring role to the spear, it did not disappear. From the mid-Sengoku period onward, the naginata survived in two primary forms.

The first was a modification called nagitata-naoshi. The technique of cutting down old naginata shafts and repurposing them as katana or wakizashi became widespread. Blades created through nagitata-naoshi possessed distinctive curvature and hamon, and many works can still be identified as nagitata-naoshi in contemporary sword appraisal.

Nagitata-naoshi blades often retain traces of the original naginata's curve in the nakago, and characteristics such as the relatively small difference between the blade's width at the base and tip, and the presence of a hi extending close to the nakago, are known diagnostic features in sword appraisal. Original signed naginata with mei are rare, and the fact that they survive today transformed into nagitata-naoshi speaks to how thoroughly weapons were utilized in that era.

The second was a conversion to religious and ceremonial use. At Shinto shrines and Buddhist temples, the naginata continued to be used as a protective and ritual weapon, and the custom of including a naginata as a bride's dowry item persisted among samurai families through the Edo period. This is the source of the naginata tradition as a martial art for women that continues into the modern naginata-dō.

The cultural influences transmitted by the naginata include the following.

• Continued use as a protective and ritual weapon at Shinto shrines and Buddhist temples
• Practice as a means of self-defense and cultivation for samurai women
• Transformation into blades through the process of nagitata-naoshi

Spear Types and Diversification—Variety in the Sengoku Period

Once the spear era began, diversification of form according to different applications occurred. While the plain spear (suyari) with a triangular cross-section was the basic form, variations became abundant, including the hooked spear (katakama-yari), cross-shaped spear (jumonji-yari), Kikuchi spear, and bamboo-leaf spear.

The hooked spear (katakama-yari) reputedly favored by Katō Kiyomasa, and the celebrated spear "Nihongo", is known to have been won by Mōri Taihei, a retainer of the Kuroda clan, from Fukushima Masanori in a drinking contest, and is currently housed in the Fukuoka City Museum. The spears of celebrated generals were also elevated to legendary status during the Sengoku through Azuchi-Momoyama periods. The spear was promoted from a mere consumable infantry weapon to a prestige weapon displaying a commander's individuality.

The length of the spear shaft and the shape of its head were chosen according to the tactical philosophy of the household or school to which the wielder belonged. When group massed assaults were prioritized, easily handled lengths of plain spears were preferred; when individual martial achievements were emphasized, complex forms like the cross-shaped spear that could entangle an opponent's weapon tended to be chosen. Even the shape of a spearhead alone reveals what its owner valued.

Naginata and Spears from the Edo Period Onward

After the establishment of the Edo shogunate, demand for spears and naginata as practical weapons declined sharply. However, the custom of carrying spears ceremonially in daimyo processions continued, and the "spear-bearing procession" persisted as an important ritual demonstrating a daimyo's status until the end of the Edo period.

The naginata continued to be practiced in samurai mansion training halls as a required subject for samurai women, and from the Meiji period onward it was incorporated into women's school education, continuing to the present day. While spear technique has been inherited as a martial art, it has not achieved the widespread adoption of naginata-dō, and in the modern era only a small number of schools such as Hōzōin-ryū spear technique maintain their lineage.

The smaller number of surviving naginata compared to katana and spears is due not only to many being transformed into nagitata-naoshi, but also to demand for them as practical weapons declining early. When appreciating and collecting swords, by taking this background into account, one can more deeply understand the weight of history carried by each nagitata-naoshi blade.

The transition from naginata to spear was not merely a question of weapon superiority but reflected a fundamental change in warfare, embodying a turning point in both the military and cultural history of Japanese society.