Sekigahara Opens the Way for the Tokugawa Shogunate

The death of the regent Toyotomi Hideyoshi in 1598 created a fragile political balance across Japan, as his five-year-old son, Toyotomi Hideyori, was left to inherit nominal rule over an unsettled coalition of warlords. Tensions soon divided the leading military figures of the realm. Ishida Mitsunari emerged as the administrative champion of the Toyotomi loyalists, while Tokugawa Ieyasu gathered prominent commanders who resented Mitsunari's conduct during and after the campaigns in Korea. By the late summer of 1600, these escalating grievances produced open war between Mitsunari's Western Army and the Eastern Army commanded by Ieyasu.

Following maneuvering around several fortifications, the two coalitions converged on the misty valley of Sekigahara in Mino Province. On the morning of October 21, 1600, the advance units stumbled into each other under dense fog created by earlier rains. Accounts differ on the exact hour: reference works usually place the start between about seven and eight o'clock in the morning, while a letter written by Tokugawa retainers two days after the battle suggests the fighting began around ten. Ii Naomasa opened the combat by leading his vanguard against the center of the Western lines, closely followed by Fukushima Masanori, initiating hours of intense clashes characterized by volleys of arrows and gunfire.