The Battle of Uozu Castle was fought in 1582 between vassals of Uesugi Kagekatsu with 4000 soldiers and that of Oda Nobunaga with more than 10,000 soldiers. The Oda forces, led by Shibata Katsuie, Sassa Narimasa, Maeda Toshiie, and Sakuma Morimasa, fresh from successfully taking Toyama Castle, besieged Uozu Castle around March 11 (March 3, 1582).

The castle commanders immediately beseeched Kagekatsu for help, but Kagekatsu's reinforcements, already depleted by the Otate no Ran, were delayed by the betrayal of Shibata Shigeie and the Oda troops remaining in Kai and Shinano after their subjugation of the Takeda.

The Oda forces weakened the castle with numerous fierce attacks. Kagekatsu personally led an army from Kasugayama Castle on May 4 (May 25, 1582). Two days later, the Oda forces occupied the outer citadel of the castle. On May 19 (June 9, 1582) the Uesugi army arrived on Uozu Castle's east bank and set up camp at Tenjin Hill. However, they could not break through Oda's besieging army, and were forced to withdraw on May 27 (June 7, 1582) when it appeared that Kasugayama Castle itself may come under attack.

Abandoned by Kagekatsu after a 3-month long siege and running out of provisions, the 13 commanders of Uesugi, Sanbonji Kagenaga, Yoshie Munenobu, Yoshie Kagesuke, Yoshie Nobukage, Ishiguchi Hiromune, Nakajou Kageyasu, Takenomata Yoshitsuna, Terashima Nagasuke, Tadenuma Yasushige, Abe Masayoshi (sp?), Wakabayashi Ienaga (sp?), Kameda Choujou (sp?), and Fujimaru Katsutoshi wrote their names on wooden tablets and committed seppuku on June 3 (June 22, 1582). Thus the castle fell to Oda.

The Oda army prepared to march on to Echigo, but news of the death of Oda Nobunaga on June 21, the day before the end of the siege, caused confusion and panic within the army, and it retreated.

<small>Note: Japanese dates given in this entry are based on the lunar calendar; Gregorian Calendar dates in () were calculated using <a href="http://www.uni-tuebingen.de/geschichte-japans/nengo_calc.htm">NengoCalc</a>.</small>