The morning air over the valley is cool, and the ground is still wet with dew. Rows of soldiers stand quietly, adjusting armor cords and tightening their grip on long wooden shafts. Banners rise above the mist, marking the presence of rival clans waiting just out of sight. Somewhere behind the lines, a commander studies the terrain, knowing that the next few hours could decide the fate of an entire province.

Scenes like this unfolded countless times during the Sengoku period (1467-1615), an age defined by political fragmentation, military ambition, and nearly constant warfare. Yet what stands out is not only the scale of these armies, but how different they were from earlier centuries. Warfare was no longer dominated solely by elite mounted samurai. Increasingly, it was shaped by large groups of ashigaru-foot soldiers drawn from common classes-organized into disciplined formations and equipped with practical weapons.

Ashigaru

At the front of these formations stood soldiers armed with the yari, a long spear that came to define Sengoku battlefields. Simple to produce and effective in formation, the yari allowed ashigaru to fight collectively, creating dense lines capable of halting cavalry and controlling movement across the field. The rise of such formations marked a shift in warfare itself: battles were no longer decided only by individual skill or mounted duels, but by coordination, numbers, and discipline. Commanders began to think less in terms of heroic charges and more in terms of positioning, timing, and maintaining formation under pressure.

Yari

Samurai still held positions of command and continued to fight, but their role was changing. Once primarily mounted archers relying on personal combat and prestige, they now operated within larger military systems. Their weapons reflected this transition. Before the katana became dominant, earlier warriors carried the tachi-a longer, more deeply curved sword worn edge-down and designed for use on horseback. The tachi belonged to a style of warfare where mobility and mounted combat were central. As fighting shifted toward infantry-based engagements and closer combat, the shorter, more practical katana gradually replaced it, better suited to the realities of crowded battlefields.

Even so, the sword remained closely tied to samurai identity. The katana, forged through careful folding and tempering, was carried not just as a weapon but as a symbol of discipline and status. In the chaos of battle, it was often drawn only when formations broke and fighting became close and immediate. Over time, figures such as Miyamoto Musashi would come to represent the ideals of swordsmanship, reinforcing the cultural significance of the blade even as warfare itself evolved.

Tachi and Katana

Alongside spears and swords, other weapons continued to shape combat. The **naginata**, with its long shaft and curved blade, allowed *sweeping strikes* that could keep opponents at a distance or disrupt mounted fighters. Though its prominence declined as spear formations became dominant, it remained an important part of Japanese martial tradition.

The Naginata

Before armies closed the distance, battles often began at range. Archers armed with the yumi, the traditional Japanese longbow, could send volleys into enemy ranks, disrupting formations before melee combat began. Its asymmetrical design made it especially effective for mounted archery, reflecting an earlier era when mobility and horseback combat defined samurai warfare. Even as new weapons appeared, the bow remained useful due to its speed and reliability.

Samurai archer riding on horseback with his Yumi the Japanese longbow

Then, in the mid-sixteenth century, another shift occurred-one that would further change the balance of power on the battlefield. Firearms, introduced by Portuguese traders in 1543, spread rapidly across Japan. These matchlock guns, known as the tanegashima, were quickly adopted and produced in large numbers. Unlike bows, they required less lifelong training, making them particularly suited for ashigaru units. This alone began to reshape recruitment and battlefield roles, as effectiveness became less tied to elite training and more to coordination and discipline.

Pistol Museum Tanegashima

What made the matchlock truly transformative, however, was not just the weapon itself but how it was used. Commanders began to rethink battlefield tactics around gunpowder. Instead of relying on shock charges or individual skill, they developed systems of controlled fire. Units of gunners were trained to fire in sequence, maintaining a steady rhythm rather than a single volley. Defensive positions were reinforced with wooden barriers or terrain advantages, turning open battlefields into structured zones of sustained fire.

Among the commanders who understood this shift most clearly was Oda Nobunaga. During the Battle of Nagashino (1575), he demonstrated how firearms could be integrated into a broader tactical system. By placing gunners behind palisades and organizing them into rotating lines, he created continuous firepower that broke the advancing cavalry of Takeda Katsuyori. The battle showed that even the most feared mounted warriors could be stopped not by superior swordsmanship, but by disciplined infantry using coordinated gunfire.

As tactics evolved, so too did the visual organization of the battlefield. War banners became essential tools of communication. Tall nobori banners marked the presence of entire clans, while smaller sashimono worn on the backs of soldiers allowed units to be identified from a distance. In the confusion of combat, these markers allowed commanders to maintain control over increasingly large and complex armies.

Samurai Battle Flags

Protection remained just as important as offense, but its design reflected both environment and material limitations. Samurai armor, known as yoroi, was constructed from small plates of iron and hardened leather, laced together with silk cords into a flexible, layered structure. High-quality iron was relatively scarce in Japan, making large solid plates impractical. Instead, armor emphasized mobility and adaptability, allowing warriors to move across uneven terrain, fight on foot or horseback, and repair damaged sections more easily.

A man wearing a Yoroi

This contrasts sharply with European plate armor, which relied on large, rigid sheets of steel to create a fully enclosed protective shell. European armor was designed to absorb heavy blows from maces, lances, and swords, prioritizing durability over flexibility. Japanese armor followed a different balance-offering protection while preserving movement. Even as firearms became more common, it evolved gradually, reinforcing key areas without abandoning flexibility.

Sengoku Armor Musuem European Plate Armour

Not all battles were fought across open ground. Castles formed the backbone of regional power, serving as both military strongholds and administrative centers. Designed with steep stone walls, narrow entrances, and complex defensive layouts, they forced attackers into disadvantageous positions while allowing defenders to maintain control. Sieges became prolonged and strategic affairs, often relying on planning rather than direct assault. The Siege of Osaka (1614-1615), in which Tokugawa Ieyasu defeated the forces of Toyotomi Hideyori, marked the final consolidation of power and the end of large-scale warfare.

With the establishment of peace under the Tokugawa shogunate, many of the weapons that had defined Sengoku battlefields were no longer needed in combat. Instead, they were preserved. Samurai families passed down swords and armor as heirlooms, while others became part of collections that would later form the foundation of museums. Today, these objects remain as both historical artifacts and works of craftsmanship.

These weapons were also preserved in another form: art. Traditional Japanese battle paintings and folding screens depict armies in motion-spears forming dense lines, banners rising above soldiers, cavalry advancing, and firearms appearing among the ranks. These images capture not only the weapons themselves but the way they were used, offering a visual record that complements the surviving artifacts.

The Battle Of Nagashino(1575)

The Siege of Osaka (1614-1615)

Taken together, these objects and images reveal an era in transition. The Sengoku period was not only a time of conflict, but a period of change-where older forms of warfare gave way to new strategies, where individual combat yielded to organized armies, and where even the role of the samurai was reshaped by the demands of a changing battlefield.