Which Japanese battle of 1600 founded the Tokugawa peace?

Sekigahara was fought on 21 October 1600 in a narrow basin between mountains, in fog, by something like 160,000 men - one of the largest battles anywhere in the world before the modern era. Tokugawa Ieyasu's eastern coalition faced Ishida Mitsunari's western one, and on paper the west had the better position: they held the high ground on three sides and outnumbered the enemy in the field.

It was decided by who did not fight. Several western contingents had been quietly negotiating with Ieyasu for months. Kobayakawa Hideaki sat on Matsuo hill with fifteen thousand men and watched the morning go by without committing; Ieyasu is said to have finally had his arquebusiers fire on Hideaki's own position to force him to choose. He charged - downhill into the western flank - and other units went over with him. The battle was finished by mid-afternoon.

Ieyasu was shogun by 1603, and the settlement he built held Japan in near-total internal peace for two and a half centuries, at the price of closing the country. He also sorted every lord into those who had backed him before Sekigahara and those who submitted after, and the second group were kept permanently at arm's length from power. Two hundred and sixty-eight years later, it was two of those outside domains, Satsuma and Choshu, that brought the shogunate down.