Takeda Shingen had spent months preparing his march. In October 1572, after securing alliances with the Later Hojo clan of Odawara and the Satomi clan of Awa, and waiting for winter snows to block the northern passes against his rival Uesugi Kenshin, Shingen led 30,000 men south from his capital of Kofu into Totomi Province. A secondary force of 5,000 under Yamagata Masakage swept into eastern Mikawa Province, quickly seizing Yoshida Castle and Futamata Castle. Shingen's goal was not Hamamatsu but Kyoto itself -- he intended to destroy Oda Nobunaga and claim the capital. He would have preferred to bypass Ieyasu entirely, saving his forces for the greater prize ahead.

Ieyasu could have stayed behind the walls of Hamamatsu Castle and let Shingen pass. His Oda-sent advisors Sakuma Nobumori and Takigawa Kazumasu urged exactly that, as did his own generals Matsudaira Koretada and Ishikawa Kazumasa. But Ieyasu understood something about the fierce Mikawa samurai who served him: to hide behind castle walls while an enemy army marched through his domain would destroy his credibility and weaken his hold on the province. He drew his forces up on Mikatagahara, a high plain just north of Hamamatsu, and waited. It was a decision born not of recklessness but of political necessity -- and it would nearly cost him everything.

The battle opened with Tokugawa arquebusiers and peasant stone-throwers firing into the Takeda formation. Ieyasu was counting on his firearms -- still relatively new to Japanese warfare -- to neutralize Shingen's cavalry advantage. The gambit failed almost immediately. Naito Masatoyo's vanguard cavalry smashed through Honda Tadakatsu's right flank, then wheeled to assault the Oda reinforcements from behind. The Oda troops broke and ran; their officer Hirate Hirohide was killed while Sakuma Nobumori and Takigawa Kazumasu fled the field. When Shingen sent fresh horsemen under Takeda Katsuyori and Obata Masamori into the weakening Tokugawa center, the entire line collapsed into disorderly retreat. One by one, Ieyasu's most loyal retainers fell: Matsudaira Koretada, Naruse Masayoshi, Toyama Kosaku, Endo Ukon -- all killed as their units were encircled and overrun.

Natsume Yoshinobu led the last of his soldiers in a suicide charge against the Takeda advance to buy time for his lord's escape, dying in the attempt. What Ieyasu did next became legend. He ordered the gates of Hamamatsu Castle thrown open and braziers lit along the approach -- an application of the ancient Empty Fort Strategy. Sakai Tadatsugu beat a great war drum from the ramparts, its deep booming echoing across the battlefield. When the Takeda vanguard under Baba Nobuharu and Yamagata Masakage saw the open gates and blazing fires and heard the drums, they halted, convinced it was a trap. They made camp short of the castle. Meanwhile, the famous Iga ninja Hattori Hanzo captured a Takeda spy named Chikuan and delayed the enemy advance at the Tenryu River with an audacious counterattack of just thirty men.

The Battle of Mikatagahara was Tokugawa Ieyasu's most devastating defeat and one of the most celebrated cavalry engagements of the Sengoku period. But Shingen never pressed his advantage. He bypassed Hamamatsu and continued his march toward Kyoto, only to be fatally wounded at the Siege of Noda Castle in February 1573. He died in May of that year, and his dream of reaching Kyoto died with him. Ieyasu survived, learned, and waited. The humiliation on the snowy plain stayed with him for decades -- tradition holds that he commissioned a portrait of himself in the immediate aftermath, haggard and defeated, as a permanent reminder never to be so reckless again. Thirty years later, the man who lost at Mikatagahara would become Shogun of all Japan.