The Man Who Almost United Japan

Of all the warlords who contested Japan during the chaotic Sengoku period (c. 1467–1615), Oda Nobunaga stands apart. Starting from a mid-ranking position in a relatively minor province, he rose to control nearly half of Japan before his assassination in 1582. His methods were radical, often brutal, and consistently effective. More than any other figure, he defined what the unification of Japan would look like — even though it would be his successors who finished the job.

Starting Position: Owari Province

Nobunaga inherited control of Owari Province (modern Aichi Prefecture) in 1551, as a teenager. Owari was strategically located in central Honshu, but Nobunaga's position was far from secure — rival clans threatened from without, and his own family was fractured by internal power struggles. His early years were spent consolidating control within Owari, sometimes by killing his own relatives.

His reputation at this stage was that of a reckless eccentric — he earned the nickname Owari no Outsuke ("The Fool of Owari") for his unconventional behavior. His rivals underestimated him. It was a mistake they would not get the opportunity to repeat.

The Battle of Okehazama (1560): Audacity as Strategy

The battle that announced Nobunaga to the world came in 1560. The powerful warlord Imagawa Yoshimoto marched a massive army — estimated at over 20,000 men — through Owari on his way to Kyoto. Nobunaga had perhaps 2,000 troops. Every rational calculation said to submit or flee.

Instead, Nobunaga launched a surprise attack during a violent thunderstorm, directly targeting Imagawa's field headquarters. The assault was so sudden and violent that Yoshimoto was killed before his army could respond. The larger force dissolved in confusion.

Okehazama demonstrated what would become a Nobunaga signature: attacking the center of gravity directly, accepting extreme risk for decisive results. He would repeat this logic throughout his career.

Military Innovations That Changed Japanese Warfare

Nobunaga's most lasting contribution was his systematic use of firearms (teppo) in battle. Guns had arrived in Japan via Portuguese traders in 1543, but most commanders treated them as curiosities or supplementary weapons. Nobunaga recognized their transformative potential.

At the Battle of Nagashino (1575), he deployed an estimated 3,000 arquebusiers in rotating volleys behind prepared wooden palisades — a technique that neutralized the famous cavalry charges of the Takeda clan. The Takeda, considered the finest horsemen in Japan, were devastated. It was one of the most significant tactical innovations in Japanese military history.

Other Nobunaga innovations included:

  • Large-scale use of ashigaru (foot soldiers) as organized professional infantry, not just rabble
  • Centralized logistics — reducing dependence on local foraging and enabling longer campaigns
  • Economic warfare — controlling key trade routes and markets to fund his military
  • Construction of Azuchi Castle, a statement of power visible for miles, symbolizing a new kind of warlord authority

The Destruction of the Buddhist Monasteries

Nobunaga's relationship with organized religion was one of conflict. The great Buddhist temple complex of Enryaku-ji on Mount Hiei had long wielded enormous political power, harboring enemies and defying secular authority. In 1571, Nobunaga destroyed it entirely, killing thousands of monks, acolytes, and civilians sheltering there.

The event shocked Japan. It also made clear that Nobunaga was not constrained by the usual rules of political conduct. He would use any level of force necessary to remove obstacles to his ambition.

The Unfinished Revolution

By 1582, Nobunaga controlled more of Japan than any previous warlord. He had abolished many internal toll barriers, promoted commerce, and was dismantling the old feudal power structures. Then, on the night of June 21, 1582, his general Akechi Mitsuhide turned against him. Surrounded at Honnō-ji temple in Kyoto, Nobunaga committed suicide rather than be captured.

His legacy passed to his general Toyotomi Hideyoshi, who completed the unification he had made possible. Japan would remember Nobunaga as one of history's most consequential military innovators — a man who broke the old world in order to build a new one.