The hill was only 86 meters tall, barely a rise in the vast flat geometry of the Nobi Plain. But it was isolated — a volcanic remnant standing alone in the middle of farmland — and from its summit a man could see in every direction. Tokugawa Ieyasu, age forty-two, looked at Komakiyama and recognized it for what it was: the best defensive position for a hundred li in any direction.

He entered Komakiyama Castle on March 15, 1584, and began turning it into a fortress.

The situation that had brought him there was, on the surface, not his quarrel. Oda Nobukatsu — second son of the recently assassinated Oda Nobunaga — had watched Hashiba Hideyoshi, his father's former general, execute three of his senior retainers and move to consolidate control over the Oda inheritance. Nobukatsu appealed to Ieyasu for help. Ieyasu agreed to provide it. The reasons were obvious: if Hideyoshi absorbed the Oda domains unchallenged, he would control central Japan and be positioned to swallow everyone else, including Ieyasu, in sequence.

This was the only direct military confrontation between the two men who would define the next two centuries of Japanese history. Hideyoshi had reunified the central provinces after Nobunaga's death. He had more money, more allies, and more men — estimates of his force at Komaki range from 60,000 to 100,000, against Ieyasu's approximately 17,000. By any conventional military calculus, Ieyasu should have been crushed.

He refused to fight on conventional terms.

From the summit of Komakiyama, Ieyasu watched Hideyoshi establish his own headquarters at Inuyama Castle to the north. The two armies built earthworks, dug trenches, and settled into a standoff that stretched across the spring. Ieyasu's retainer Sakakibara Yasumasa had recommended the hill, and the choice proved decisive: Hideyoshi's massive army could not assault the position without unacceptable losses, and could not ignore it without leaving an armed enemy force in their rear.

The stalemate became its own kind of pressure. Hideyoshi needed a result. He was, for the first time in his career, unable to simply apply overwhelming force and move on. Ieyasu was costing him time.

The breaking point came when Ikeda Tsuneoki — one of Hideyoshi's most trusted generals, a man who had grown up in the Oda household — proposed a solution: take 20,000 men on a flanking march through Mikawa Province, Ieyasu's home territory. The threat to Mikawa would force Ieyasu off the hill to defend his heartland, and then Hideyoshi could crush him in open ground.

Ieyasu did not go off the hill. Instead, he moved fast enough to intercept.

The encounter at Nagakute (長久手) on April 9 lasted roughly two hours. Ieyasu's forces caught Ikeda's column mid-march, in terrain unsuited to the large force's advantages. The result was annihilation: Ikeda Tsuneoki was killed, along with his son Yukisuke and his son-in-law Mori Nagayoshi, two of Hideyoshi's finest field commanders. Casualty estimates for Hideyoshi's side range from 3,000 to 6,000 men.

It was the cleanest battlefield victory of Ieyasu's career to that point. And he followed it by doing almost nothing.

Hideyoshi shifted strategy. Unable to defeat Ieyasu directly, he moved against Nobukatsu's weaker castles, pressuring Ieyasu's ally rather than Ieyasu himself. Nobukatsu, watching his holdings erode, made a separate peace with Hideyoshi by late 1584. This was the masterstroke — Ieyasu had no legal justification to keep fighting a war on behalf of a man who had stopped fighting it. He accepted Hideyoshi's supremacy through diplomacy, sending his son as a hostage-adoption and eventually, in 1586, travelling to Osaka to pay formal homage.

On the surface this looked like defeat. Ieyasu had won the battle and surrendered the war. But read forward through the next eighteen years, the logic becomes clear. By accepting Hideyoshi's supremacy, Ieyasu preserved his domains, his army, and his life. Hideyoshi died in 1598, leaving an infant heir and a council of regents that immediately began fracturing. Ieyasu was positioned — experienced, powerful, patient — to move. At Sekigahara (関ヶ原) in 1600, he destroyed the last coalition that could have stopped him. In 1603, he founded the Tokugawa Shogunate (徳川幕府, Tokugawa Bakufu).

The road from that 86-meter hill in 1584 to the shogunate's founding in 1603 was not a straight line, but the direction was consistent. Ieyasu's patience at Komaki established the template for everything that followed: identify the best ground, hold it, wait for the enemy to make the mistake that lets you finish them. He was forty-two at Komakiyama. He was sixty-two when he became shogun. He was seventy-three when he finally ended the Sengoku era at Osaka.

The man who chose the hill outlasted everyone.