In July, Mitsunari, among others, took up arms (the Battle of Sekigahara) during the absence of Ieyasu, who had gone on an expedition, and as Ieyasu decided to go westward, Kagekatsu dispatched expeditionary forces from Aizu.
7月、討伐に向かった家康の留守中に三成らが挙兵（関ヶ原の戦い）し、家康が西上するとなると会津から出兵。