Kagekatsu was the second son of Nagao Echizen no Kami Masakage (d.1564), husband of Uesugi Kenshin's elder sister Ayahime. As a child he was known as Kiheiji. Kenshin adopted him and named him part heir alongside Uesugi Kagetora (Hojo Ujiyasu's 7th son, adopted by Kenshin in 1569). Following Kenshin's death in 1578 Kagekatsu found a pretext to feud with Kagetora and the resulting civil war became known as the Otate no Ran. By 1579 Kagekatsu had gained the upper hand and forced Kagetora to commit suicide. This bloody division allowed Oda Nobunaga's generals (headed by Shibata Katsuie) to conquer the Uesugi's lands in Kaga, Noto, and Etchu.
In 1582 Kagekatsu led an army into Etchu and was defeated by Oda forces at the Battle of Tenjinyama. He hastily returned to Echigo when he learned that Oda general Mori Nagayoshi had raided Echigo in his absence. When Uozu castle in Etchu fell to the Oda, in the course of which a number of important Uesugi retainers were killed, Kagekatsu's fortunes appeared bleak. The Uesugi were given a reprieve with the death of Nobunaga shortly afterwards. Kagekatsu made friendly overtures to Hashiba (Toyotomi) Hideyoshi, and attacked Shibata Kasuie's northern outposts during the Shizugatake Campaign (1583). He was therefore confirmed in his Echigo fief (worth 550,000 koku) and went on to support Hideyoshi during the Komaki Campaign (1584), in which he played a limited role by launching a foray into Shinano. He attacked Hojo forts in Kozuke during the 1590 Odawara Campaign and in 1598 was transferred to Aizu (worth almost 1,000,000 koku), an area of western Mutsu controlled by the Ashina prior to 1589.
That same year he was named one of Five Regents (Go-Tairo) and following Hideyoshi's death grew hostile to Tokugawa Ieyasu. In 1600 Kagekatsu began preparations for war, and in effect opened the Sekigahara Campaign. His army, which Ishida Mitsunari had hoped would tie down Tokugawa Ieyasu himself, clashed with the forces of Date Masamune and Mogami Yoshiakira and gained little in the battles conducted in and around Aizu. After the Tokugawa victory at the Battle of Sekigahara, Ieyasu transferred the Uesugi from their 1.2 million koku fief to Yonezawa domain (300,000 koku). While this left the Uesugi still one of the wealthiest clans in the realm, despite their prominent place in opposition to Ieyasu, Morgan Pitelka argues that it was precisely out of respect for that prominence - i.e., for the Uesugi's status, power, reputation - that they deserved, perhaps even were entitled, to remain quite prominent; Pitelka emphasizes, too, that the drop by some 900,000 koku was still a massive loss, a heavy blow to the Uesugi, appropriate given their opposition and defeat, even if it did leave them still among the most wealthy. Meanwhile, roughly half of Kagekatsu's previous territory, Aizu domain, now reduced to 600,000 koku, was granted to the Tokugawa-loyal warlord Gamô Hideyuki.
Kagekatsu was able to redeem himself somewhat by taking part in the Osaka castle campaigns. At the Battle of Shigeno (1614) Kagekatsu led 5,000 men into action against the Osaka defenders and distinguished himself by refusing an offer by Ieyasu to retire for rest. Kagekatsu, who died at Yonezawa in 1623, was remembered as a dour, humorless man. Although considered a capable enough general, his record was clearly an uneven one.
- Initial text from Samurai-Archives.com FWSeal & CEWest, 2005
- Morgan Pitelka, Spectacular Accumulation, University of Hawaii Press (2016), 83.