The samurai who despised Ishida Mitsunari had a point — and they were completely wrong. He was not a warrior. He had never been a warrior. Born in 1559, he had risen through the Toyotomi administration on the strength of his mind: meticulous, efficient, incorruptible, and utterly relentless. As one of Hideyoshi's five 奉行 (bugyō), he had managed the logistics of two invasions of Korea, the finances of the Toyotomi state, and the political machinery of the most powerful regime in Japanese history. What he had not done was lead men in battle. The generals remembered this every time they looked at him.

In the summer of 1600, that distinction ceased to matter. Tokugawa Ieyasu, the one man with both the power and the ambition to dismantle everything Hideyoshi had built, had marched his army north to confront the Uesugi clan — leaving the Toyotomi heartland exposed. Mitsunari saw the window and acted with the same precision he had applied to every task of his career. He began working the phones — or rather, the messenger relay system — of feudal Japan.

His first target was Otani Yoshitsugu, his oldest and most trusted friend. Yoshitsugu was dying. Leprosy had taken his eyesight and ravaged his body; he had to be carried in a palanquin. He knew perfectly well what joining Mitsunari's coalition meant. He agreed anyway. If Mitsunari was going to die for this cause, Yoshitsugu would die with him. He did, at Sekigahara, ordering his own men to kill him rather than be captured.

The coalition-building moved with astonishing speed. August 16: Otani joins. August 17: the conspirators meet at Sawayama and draft the invitation to Mori Terumoto. August 22: the Western Army 西軍 (Seigun) is formally proclaimed at Osaka Castle, claiming to act as guardians of the seven-year-old Toyotomi heir Hideyori. Six days, from a bureaucrat's desk, to an army of 80,000.

The nomination of Mori Terumoto as commander-in-chief was the cleverest stroke of all. The Mori clan was one of the great western houses — their name gave the coalition the legitimacy Mitsunari could not supply himself. And Terumoto, for his part, accepted the honor and stayed home. The supreme commander of the Western Army never left Osaka Castle. After Sekigahara, Ieyasu assessed the situation with cold clarity and let him live — stripping his domain from 1.2 million koku to 369,000, but sparing his life. The man who lent his name to a rebellion and contributed nothing was permitted to survive it.

Mitsunari was not so lucky. He was 41 years old, and he knew that most of the daimyo he was recruiting were lukewarm or actively duplicitous. Kobayakawa Hideaki was already in quiet communication with Ieyasu. Kikkawa Hiroie had promised to stand still rather than fight. Mitsunari built his coalition out of reluctant partners, on a ticking clock, against the most powerful man in Japan. He was a 奉行 (bugyō) who had decided that administration was not enough — that if the Toyotomi legacy was to survive, someone had to pick up a weapon. He was executed by beheading on November 6, 1600, seven weeks after Sekigahara. But the outcome was not inevitable. Had Kobayakawa not defected mid-battle, the bureaucrat might have won.