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

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

The naginata (薙刀) shone as the leading weapon in Japanese warfare from the late Heian period through the Nanboku-chō period (14th century). With its long shaft and curved blade, the naginata proved devastating as a slashing weapon—mounted samurai targeted cavalry horses' legs while rotating their bodies to deliver wide sweeping strikes.

War chronicles depicting the Genpei War frequently feature spectacular single combat scenes involving naginata, and legends such as Benkei gathering a thousand naginata on a bridge demonstrate that this was recognized by the common people as the representative weapon of the age.

During the Kamakura period, naginata technique became a formal training subject for samurai families, and by the turbulent Nanboku-chō era, foot soldiers (ashigaru) armed with naginata were executing organized assault tactics. The large naginata of this period often exceeded one meter in blade length, making them sophisticated weapons requiring both strength and technical skill.

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

The Ōnin War (1467–1477) marked a clear shift in which weapon dominated the battlefield. Multiple factors converged to drive this transformation.

Factor 1: Change in Group Tactics The greatest driving force was the appearance of large numbers of ashigaru (foot soldiers) from non-samurai backgrounds in light armor. These foot soldiers, lacking formal martial training, could not easily master the advanced techniques required for naginata. In contrast, spears—with their simpler "thrust" motion—could be deployed in actual combat after only short-term training, offering a significant tactical advantage.

Factor 2: Manufacturing Cost and Availability of Spears Naginata production requires advanced forging techniques to create large curved blades, whereas triangular cross-section spear heads possess relatively simple shapes suitable for mass production. In the Sengoku period's system of mass mobilization, the mass-production capability of weapons became strategically vital, and the spear's superiority became undeniable.

Factor 3: Efficiency of Long-Shaft Weapons The long-shafted spear was optimized for simultaneous thrusts by densely packed formations. The tactic known as the "spear hedge" (yarubusuma)—densely clustered spears advancing together—proved effective even against mounted samurai and became a group tactic independent of individual skill. Sengoku daimyo eagerly adopted this strategy.

Naginata's Survival Strategy — Modification and Change of Use

Though the naginata ceded its primary role to the spear, it did not disappear. From the mid-Sengoku period onward, the naginata survived primarily in two forms.

The first was a modification called "naginata naoshi" (naginata conversion). The practice of shortening old naginata shafts and repurposing them as katana or wakizashi became widespread. Swords created through naginata naoshi possess distinctive curves and grain patterns, and many such pieces remain identifiable as "naginata naoshi" in modern sword authentication.

The second was conversion to religious and ceremonial use. Shinto shrines and Buddhist temples continued to use naginata as protective and ritual weapons. Particularly, it was customary for samurai women to receive a single naginata as part of their marriage dowry through the Edo period. This tradition became the cultural wellspring of naginatadō (naginata martial art) as a women's martial discipline.

Types and Diversification of Spears — Sengoku-Period Variety

As the spear era began, forms diversified according to function. The triangular cross-section plain spear (suyari) was the basic form, but variants flourished—including the single-crescent spear (katakama-yari), cross-shaped spear (jūmonji-yari), Kikuchi spear, and sasaho spear.

Legendary generals' favorite spears became the stuff of legend: Katō Kiyomasa's "snake spear" (hebi-yari, a type of cross-shaped spear) and Fukushima Masanori's "Nihon-gō," named during the Sengoku and Azuchi-Momoyama periods. The spear rose from a mere infantry consumable to a prestigious weapon displaying a commander's individuality.

Naginata and Spears After the Edo Period

After the Edo Shogunate's establishment, demand for spears and naginata as practical weapons plummeted. Yet the custom of ceremonial spear-bearing in daimyo processions persisted, and the "spear-bearing procession" remained an important ritual demonstrating a daimyo's rank until the end of the Edo period.

The naginata survived as a mandatory subject for samurai women in their residential training halls, and after the Meiji period was adopted as part of girls' school education, continuing to the present day. While spear technique has been transmitted as a martial art, it lacks the popularity of naginatadō, and only a handful of schools such as Hōzōin-ryū spear technique maintain the tradition today.

The shift in dominant role from naginata to spear was not merely a matter of weapon superiority, but rather reflected a fundamental change in warfare itself and embodied a turning point in both the military and cultural evolution of Japanese society.