Mogami clan
After the death of Kenshin in 1578 Shigenaga supported Uesugi Kagekatsu as successor during the Siege of Otate. In 1588, Shigenaga once again entered conflict against the Mogami clan where he defeated a Mogami army at the battle of Jugorihara (十五里ヶ原の戦い). When Mogami Yoshiaki expanding his territory into the Shōnai region in Dewa province and threatened Yoshiuji Daihoji, who sought aid from Shigenaga. Together they successfully recovered the Shōnai region as a territory of the Uesugi clan. In 1598, Uesugi Kagekatsu was transferred to Aizu Wakamatsu castle (Fukushima prefecture) by the Toyotomi government, and Shigenaga was transferred to the Aizu region.