The Sekigahara Campaign was a series of battles in Japan fought between the Eastern Army aligned with Tokugawa Ieyasu and the Western Army loyal to Ishida Mitsunari, culminating in the decisive Battle of Sekigahara. The conflict was sparked by a punitive expedition led by Ieyasu against the Uesugi clan in the northeastern Tōhoku region, providing Mitsunari with an opportunity to denounce Ieyasu in the name of the infant ruling taikō Toyotomi Hideyori while the Tokugawa troops were in the field. Much of the campaign consisted of a struggle to control key castles on the Tōkaidō and the Nakasendō, the main roads linking Edo and the capital of Kyoto. However, battles and sieges far from these key highways, both in the Tōhoku and in pockets of resistance around the capital, had wide-reaching effects on the manoeuvring and availability of troops for the decisive battle at Sekigahara. The campaign also spilled over briefly into the southern island of Kyūshū, but Ieyasu quickly ordered his forces to stand down following his victory for political reasons. The campaign dramatically changed the political landscape of Japan, resulting in the ascendancy of the Tokugawa Shogunate over the Toyotomi clan and the shifting of political power between the various daimyō who participated in it. Background With the death of Toyotomi Hideyoshi in 1598, his 5 year-old son Toyotomi Hideyori succeeded him formally as the taikō or imperial regent, and rule of Japan fell under a Council of Five Elders appointed by Hideyoshi as regents for Hideyori until he came of age. Tokugawa Ieyasu, a member of the council, installed himself in Hideyoshi's former residence of Fushimi Castle and arranged political marriages for his children in defiance of the council's restriction on doing so, drawing political ire. Ishida Mitsunari, one of the Five Commissioners appointed to civil administration by Hideyoshi, attempted to approach Maeda Toshiie, a councilman and guardian of Hideyori, at Ōsaka Castle to conspire against Ieyasu; however, the intervention of Hosokawa Tadaoki, a friend of Ieyasu and of the Maeda clan, convinced Toshiie's son Toshinaga to dissuade Toshiie from opposing Ieyasu. Mitsunari resorted to attempting an assassination plot on Ieyasu, but when the plot failed, several of Ieyasu's generals independently attempted to eliminate Mitsunari. Mitsunari infamously escaped the castle at night disguised as a woman and fled to Fushimi Castle to beg Ieyasu to protect him from retaliation. Ieyasu agreed on the condition that Mitsunari go