The smoke had barely cleared from Sekigahara when Tokugawa Ieyasu (徳川家康, Tokugawa Ieyasu) began something far more consequential than the battle itself.

The fighting had lasted six hours. What followed lasted centuries.

In the weeks after October 21, 1600, Ieyasu — 57 years old, patient beyond measure, and finally in undisputed command of Japan — confiscated 6.3 million 石 (koku) of agricultural output from the losing Western Army and its allies. That figure represented roughly one-third of everything Japan produced. Families who had held their domains for generations found themselves erased from the map by administrative order, with no second battle required and no appeal available.

The punishments came with architectural precision. Mōri Terumoto (毛利輝元, Mōri Terumoto), who had commanded the most powerful domain in western Japan, was reduced from eight provinces to two — Nagato and Suō, worth about 369,000 koku. Uesugi Kagekatsu (上杉景勝, Uesugi Kagekatsu), who had refused to come to Fushimi on Ieyasu's orders in the months before the battle, saw his fief cut by 75%, from 1.2 million to 300,000 koku in distant Yonezawa. Between 88 and 93 clans suffered 改易 (kaieki), the formal Tokugawa sanction that abolished a lord's domain and rank entirely — stripping not just land and income, but the social identity of an entire family and all the retainers who depended on them.

The rewards were equally deliberate. Kobayakawa Hideaki (小早川秀秋, Kobayakawa Hideaki), whose last-minute defection had swung the entire battle, received a 520,000-koku domain in Bizen and Mimasaka. Yuki Hideyasu (結城秀康, Yuki Hideyasu) received all of Echizen Province at 670,000 koku. The tozama (外様, tozama) — lords who had joined Ieyasu only after Sekigahara — received increased but deliberately distant territories, positioned where, if they ever rebelled, the Tokugawa would have time to mobilize against them. Ieyasu was not just punishing enemies and rewarding allies. He was placing people on a board.

On November 6, the Western Army's chief strategist Ishida Mitsunari (石田三成, Ishida Mitsunari) was executed at the dry riverbed of the Kamo River in Kyoto. Along with Konishi Yukinaga (小西行長, Konishi Yukinaga) and Ankokuji Ekei (安国寺恵瓊, Ankokuji Ekei), he had been paraded around Osaka with an iron ring around his neck before his execution — and notably, all three were denied the honor of seppuku and simply beheaded. His head was displayed at Sanjō Bridge (三条大橋, Sanjō Ōhashi) for the public to see. According to a widely told story, offered a persimmon by a bystander on the way to his death, Mitsunari refused it on the grounds that it would be bad for his digestion — a final act of composure, or dark humor, that became legendary.

Ieyasu's Tokugawa clan itself grew from 2.5 million to 4 million koku. Strategic cities, transport routes, and mines passed into direct Tokugawa control. The redistribution was so swift — completed within weeks — that potential resisters never had time to organize. By December 1600, the map of Japan had been redrawn.

The deeper significance lay in what the redistribution revealed about power. The Sengoku era — a century of civil war in which any warlord with enough force could seize new territory — did not truly end at the Battle of Sekigahara. It ended in the weeks that followed, when Ieyasu demonstrated that military victory alone was insufficient; the real power was administrative. The power to erase a daimyo family from the map with a written order, backed by the implied threat of overwhelming force, was a different kind of weapon than any sword or arquebus.

The tozama lords who survived — Mōri, Shimazu (島津, Shimazu), Uesugi, Chōshū (長州, Chōshū), Satsuma (薩摩, Satsuma) — retained enough land to preserve their dignity and their grievances. Ieyasu did not destroy them completely. He left them reduced, relocated, and watching. That calculation, too, proved correct in ways he could not have predicted: it was precisely these clans, still nursing the memory of Sekigahara, who finally dismantled the Tokugawa in 1868, more than two and a half centuries later.