The 1578 siege of Ōtate took place following the sudden death of Uesugi Kenshin

Uesugi Kenshin

was a daimyo who ruled Echigo province in the Sengoku period of Japan.He was one of the most powerful lords of the Sengoku period. While chiefly remembered for his prowess on the battlefield, Kenshin is also regarded as an extremely skillful administrator who fostered the growth of local industries...

, one of Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

's greatest warlords. Kenshin had requested that the inheritance be split between his nephew, Uesugi Kagekatsu

Uesugi Kagekatsu

was a daimyo during the Sengoku and Edo periods of Japanese history. The son of Nagao Masakage and husband of Uesugi Kenshin's elder sister, Aya-Gozen. After his father died, he was adopted by Kenshin....

, and his adopted son Uesugi Kagetora

Uesugi Kagetora

was the seventh son of Hōjō Ujiyasu; he was adopted by Uesugi Kenshin, and was meant to be Kenshin's heir. However, in 1578, he was attacked in his castle at Ōtate by Uesugi Kagekatsu--Kagetora's respective brother-in-law—and was subsequently defeated. Kagetora committed suicide the following...

.

Thus, on March 17 1578, Uesugi Kagekatsu led a force from his castle at Kasugayama

Kasugayama Castle

' was the primary fortress of the Japanese warlord Uesugi Kenshin during the Sengoku period. It is situated in what is now the city of Jōetsu, Niigata prefecture, and was originally built and ruled by the Nagao clan....

 to besiege his cousin's Ōtate castle. The castle fell, Kagetora committed seppuku

Seppuku

is a form of Japanese ritual suicide by disembowelment. Seppuku was originally reserved only for samurai. Part of the samurai bushido honor code, seppuku was either used voluntarily by samurai to die with honor rather than fall into the hands of their enemies , or as a form of capital punishment...

, and Kagekatsu claimed the full inheritance.