The Betrayers of Sekigahara: What Happened to the Men Who Switched Sides

The Battle of Sekigahara, fought on October 21st, 1600, is usually told as a story of tactics and terrain. It was actually a story of letters. In the months before the battle, Tokugawa Ieyasu had spent more time writing than marching, opening secret correspondence with at least four major Western Army commanders and convincing each of them, separately, that the right moment to switch sides would be the moment he gave the signal. When the signal came, mid-afternoon on the 21st, the Western line collapsed sideways. The fight on the field was over in roughly six hours.

What happened to the men who turned the tide — and what their fates tell us about how Ieyasu treated useful traitors — is the part that doesn't make the chronicles' first chapter.

Kobayakawa Hideaki

The most famous defector was Kobayakawa Hideaki, the twenty-year-old commander of fifteen thousand troops on Mount Matsuo on the Western Army's southern flank. He had been promised the entire Chūgoku region by Ieyasu — five hundred thousand koku of new territory if he switched. He hesitated through the morning. When Ieyasu's arquebusiers fired ranging shots at his stationary line just after noon, he charged downhill not against Ieyasu but against his own ally Ōtani Yoshitsugu. Within an hour the Western Army folded.

Ieyasu paid the bill. Hideaki was given Bizen and Mimasaka, fifty-five domains' worth of fertile rice plains, a holding of 510,000 koku that should have made him one of the great lords of the new order. He held it for two years. Edo-period accounts agree he descended into compulsive drinking, declined rapidly into paranoia and physical illness, and died in 1602 at twenty-one. His line ended without an heir. The Kobayakawa family was extinguished within months. Edo-period folklore claimed the ghost of Ōtani Yoshitsugu haunted him to death.

Wakisaka Yasuharu

Wakisaka Yasuharu commanded a smaller contingent on the same flank, a veteran of the Korean invasions and a Toyotomi insider. He defected at almost the same moment as Kobayakawa. Ieyasu kept him in the Awaji domain he already held — only thirty thousand koku, no upgrade, despite the secret promises that had brought him in. The implicit signal was clear: betrayal earned survival, not reward. Wakisaka served loyally for the rest of his life and his line continued, but Awaji was a strategic backwater. He died in 1626 a man who had bet everything on a switch and broken even.

Kuchiki Mototsuna and Ogawa Suketada

The two smaller defectors fared worse than Wakisaka. Kuchiki Mototsuna, who turned at roughly the same minute as Kobayakawa and Wakisaka, was permitted to keep his small Tamba domain but was politically frozen — never trusted enough for major office. Ogawa Suketada was reduced from thirty thousand to seven thousand koku within two years, on charges Edo-period historians considered fabricated, and his line was extinguished in 1610.

Kikkawa Hiroie: The Loyal Traitor

The fifth and least-discussed defector was Kikkawa Hiroie, who controlled the Mōri clan's huge but stationary force on Mount Nangū above the Tokugawa right flank. Kikkawa had reached a private agreement with Ieyasu's representatives in advance: in exchange for a guarantee that the Mōri's 1.2 million koku domain would be preserved intact, Kikkawa would block the Mōri commander Mōri Hidemoto from descending the mountain to attack. Kikkawa kept his word. The Mōri force, the largest single contingent in the Western Army, sat motionless on the mountain for the entire battle, asking repeatedly for permission to advance and being told by Kikkawa that it was 'still too early.'

After the victory, Ieyasu broke the agreement. The Mōri were stripped of three-quarters of their territory and reduced to the small Hagi domain of 369,000 koku. Kikkawa Hiroie spent the rest of his life being blamed by his own clan for the loss, and the Mōri of Hagi spent the next 268 years quietly nursing a grudge. The grudge surfaced in 1868: it was the Mōri of Hagi, more than any other domain, who organized the Meiji Restoration and finally brought down the house of Tokugawa.

The Pattern

Read together, the post-Sekigahara fates of the betrayers tell a single story. Ieyasu paid only Kobayakawa, the largest and most pivotal defector, and even that payment turned to ruin within two years — possibly because Ieyasu found the new boy lord politically inconvenient and let nature finish him. The smaller switchers received survival but no advancement. The man whose treachery technically saved the Mōri — Kikkawa — saved them at the cost of being forever despised, and the cost was paid in full when the Mōri took their revenge two and a half centuries later.

Ieyasu's verdict on betrayal, by deeds rather than words, was that it was useful and disposable. The men who fought for him at Sekigahara — the fudai daimyō who had stood with the Tokugawa from before the battle — built dynasties. The men who switched on the day built tombs.

"Reward the loyal in proportion to their service; reward the traitor only enough to keep him from regretting the betrayal."