The ledgers said he was winning. This was the tragedy of Ishida Mitsunari (石田三成).

In the weeks leading up to September 14, 1600, Mitsunari had assembled the 西軍 (Seigun) — the Western Army — the largest military coalition since Toyotomi Hideyoshi's death two years earlier. More than 120,000 men had gathered under the Western banner. Against them, Tokugawa Ieyasu's Eastern Army numbered roughly 75,000. The numbers seemed decisive. Mitsunari had also secured something equally important: political legitimacy. On August 22, he had issued thirteen formal charges against Ieyasu on behalf of the Five Commissioners, accusing Ieyasu of betraying the late Hideyoshi's wishes and threatening the inheritance of Hideyoshi's young son, Hideyori. The document gave the Western coalition a legal and moral framework — they were not rebels. They were guardians.

Mitsunari was 41 years old. He had spent his entire career as an administrator — managing Hideyoshi's logistics, conducting cadastral surveys, drafting the political correspondence that moved an empire. He was exceptionally good at it. His entire professional worldview rested on a belief that careful preparation and correct inputs produce correct outputs.

He was not wrong about the preparation. He was wrong about the inputs.

Nominal supreme commander of the Western Army was Mōri Terumoto (毛利輝元), lord of domains worth 1.2 million koku and master of the most powerful western clan in Japan. Terumoto accepted the command. He entered Osaka Castle and remained there for the duration of the campaign. On the day of the battle — October 21, at Sekigahara — Mōri Terumoto was in Osaka. He contributed nothing, because his retainer Kikkawa Hiroie (吉川広家) had already concluded a private arrangement with Ieyasu: the Mōri vanguard would stand immobile on the Nangū-san road, blocking 36,000 western troops from reaching the battlefield. The largest single force in the Western coalition was neutralized before the campaign began.

Kobayakawa Hideaki (小早川秀秋) commanded 15,000 men on the heights above the Sekigahara valley — the most strategically decisive position on the field. He was 22 years old, the adopted nephew of Hideyoshi, commanding a force large enough to determine the battle's outcome by themselves. He was also in secret correspondence with Tokugawa Ieyasu, waiting for the signal to switch sides.

The only man who would prove entirely loyal to Mitsunari was Ōtani Yoshitsugu (大谷吉継). Yoshitsugu was Mitsunari's closest friend — perhaps the only person in Japan who genuinely cared about the man, not just the coalition. He was also dying. Contemporaries described him as suffering from what they called leprosy — likely Hansen's disease — that had left him visibly disfigured and nearly blind. He traveled in a palanquin. He reportedly told Mitsunari directly that the alliance would fail — that the western lords could not be trusted, that the numbers were an illusion. Then he joined anyway, out of friendship, and died at Sekigahara fighting to the end, surrounded on multiple sides when four western divisions also switched allegiances and attacked him simultaneously.

From the western lord's perspective on the eve of September 15 — the day Mitsunari's army would march into Ogaki Castle and take up their forward position — the war looked like it might be won. The larger force was assembled. The political justification was documented. The strategy was sound on paper.

The paper, as it turned out, had already been written on by someone else.