A Fractured Empire
The waning decades of the Ashikaga shogunate marked the beginning of a deepening crisis in Japan’s political landscape. Although the Ashikaga clan had established the Muromachi shogunate in the 14th century, creating an appearance of centralized rule, their grip on power weakened dramatically by the mid-15th century. The shogunate’s inability to enforce authority over the provincial daimyō—a class of influential regional lords—eroded any sense of cohesive national governance. This failure led to the emergence of a patchwork of increasingly independent domains, each ruled according to its own ambitions and interests.
This growing fragmentation reached a tipping point as symbolic power in Kyoto gave way to tangible authority in the countryside. The Ashikaga shoguns became little more than figureheads, while regional warlords began levying taxes, raising private armies, and issuing their own decrees. The once unified empire splintered into a battleground of rival clans, each striving for supremacy. This fracturing of central control set the stage for the Sengoku period—a century-long era defined by endless battles, shifting allegiances, and the relentless pursuit of dominance.
Cracks in the Order
As the authority of the Ashikaga shogunate began to crumble in the 15th century, fissures widened within Japan’s once-centralized feudal structure. The shogunate’s weakened leadership, plagued by political infighting and a failure to control distant provinces, unraveled the relative peace maintained since earlier eras. Enter the daimyō—regional lords who saw in this turmoil a path to greater power.
Freed from rigid shogunal oversight, these warlords created their own armies, fortified their territories, and engaged in local disputes to expand influence or settle age-old rivalries. Some gained land through military might, while others attracted followers through promises of protection and better rule for peasants and lesser samurai. The shogunate, powerless to enforce decisions, increasingly represented mere legitimacy rather than real authority.
This decentralization marked a profound transformation. Japan slipped from a state governed by a solitary military regime into a fragmented land where loyalty was given locally and alliances shifted with the tides of battle. The resulting instability and power struggles upset the fragile balance, ushering in the chaotic Sengoku period.
The Ōnin War’s Spark
The spark that ignited the Sengoku period came in 1467 with the onset of the Ōnin War. A succession crisis within the Ashikaga shogunate—triggered by Shōgun Ashikaga Yoshimasa’s failure to name a clear heir—set rival factions at each other’s throats. Supporters of Yoshimasa’s brother, Yoshimi, clashed with those loyal to his infant son, Mirroring earlier rifts, ambitious daimyō took advantage to press their claims and deepen divisions.
The war swiftly turned Kyoto into a wasteland as opposing armies led by Hosokawa Katsumoto and Yamana Sōzen devastated the ancient capital, reducing grand residences and sacred temples to smoldering ruins. As fighting spread and central authority collapsed, alliances became fluid and personal vendettas supplanted old loyalties. The chaos shattered any possibility of clear victory; instead, it created an enduring legacy of unrest.
When the war officially ended in 1477 with no decisive outcome, it left the Ashikaga shogunate irreparably weakened. Regional warlords stepped into the void, carving autonomous realms. With the old order broken, Japan plunged into an era where strength, strategy, and ambition—not inherited status—were the primary currencies of power.
Rise of the Samurai Lords
With the power of the Ashikaga shogunate in tatters, a new breed of leaders arose: the samurai lords, or daimyō. These once-loyal retainers became rulers in their own right, seizing the moment to attain lands and authority. The collapse of centralized governance enabled these warlords to transform into fully autonomous figures, each governing their lands with virtually no interference from Kyoto.
The daimyō built and maintained their own armies, imposed taxes, and managed the day-to-day lives of those within their territories. They expanded their domains through conquest, survival dictated by their ability to defend and grow their holdings. As the bonds to the shogunate loosened, loyalty was redirected to those who could best offer protection and prosperity.
This new feudal order ignited constant rivalry and shifting alliances. Former vassals became competitors, capturing castles and fighting to raise their stature. The transformation of samurai culture—from disciplined retainer to ambitious lord—drove the violence and complexity of the Sengoku period, turning Japan into a landscape crisscrossed by conflict and constantly evolving political fortunes.
The Code of the Sword
Amid the violence and upheaval of the Sengoku period, the samurai class clung to a set of guiding principles: Bushidō, or the “Way of the Warrior.” Though the notion of Bushidō would only be fully codified later, its fundamental tenets—loyalty, honor, discipline, and strategic acumen—took firm root during this tumultuous era. In a landscape where trust was rare and the tides of war shifted swiftly, these values became essential for both survival and self-worth.
Loyalty to one’s lord was non-negotiable, often demanded to the point of sacrifice. In a world rife with betrayal and sudden reversals, unbending fidelity marked the true samurai. Discipline extended beyond martial skill, encompassing the arts, philosophy, and a pursuit of personal equilibrium. Samurai were expected to master the sword and bow while also cultivating refined pursuits like poetry and calligraphy.
Equally crucial was adaptability in warfare. The romantic image of chivalrous duels gave way to the reality of complex tactics: raids, misinformation, and ever-shifting pacts. Victory belonged to the cunning and the prepared. Ultimately, the evolving code of the samurai served as both compass and armor, fortifying the soul against the turbulence of war and anchoring the warrior class in an age otherwise defined by chaos.
Seeds of Unification
Out of the chaos and division of the early Sengoku period, a new vision for Japan’s future began to take shape. The relentless ambition and tactical brilliance of figures like Oda Nobunaga and Toyotomi Hideyoshi shifted the momentum from endless division towards the possibility of unification.
Oda Nobunaga, hailing from modest beginnings, revolutionized Japanese warfare and politics. He modernized armies, harnessed the power of firearms, and shattered powerful Buddhist militias that had long asserted their own authority. His bold strategies and key victories—such as the surprise attack at Okehazama—marked the dawning of a new age, where centralizing figures challenged tradition and seized control through innovation.
Toyotomi Hideyoshi, Nobunaga’s astute protégé, continued the work of breaking down barriers between domains. Rising from humble origins, he implemented sweeping reforms that redefined the relationship between warrior and land, such as the sword hunt—disarming pockets of resistance—and comprehensive land surveys. These measures solidified his authority and began to knit the fractured archipelago into a more cohesive political entity.
Though true unity would come only with Tokugawa Ieyasu at the start of the 17th century, the legacy of Nobunaga and Hideyoshi was undeniable. Their drives for order and centralization planted the seeds from which a unified and enduring Japanese state would eventually grow, bringing to a close the age of warring states and heralding the dawn of a new era.
