The Siege of Uozu Castle occurred from 3/11 to 6/3 of Tenshō 10 (1582) in the environs of Uozu Castle in Etchū Province.  This conflict was waged between the Oda army under the command of Shibata Katsuie and the Uesugi army under Uesugi Kagekatsu.

Prelude

In 1576, the Uesugi and Oda clans were allies vis-à-vis the Takeda of Kai Province and the Gohōjō of Sagami Province.  Ashikaga Yoshiaki, the deposed shōgun sheltering with the Mōri clan (a key rival of the Oda), then rallied opponents of Nobunaga for an encirclement campaign.  Similarly, Uesugi Kenshin reconciled with the Hongan Temple (an enemy of the Oda), thereby rupturing the alliance between the Uesugi and the Oda.  In 1578, after the death of Kenshin, the Uesugi were beset by a succession struggle known as the Otate Conflict, after which Uesugi Kagekatsu became the next head of the Yamanouchi-Uesugi family (the main branch of the clan).  Kagekatsu proceeded to ally with the Takeda (another enemy of the Oda) so that the Uesugi and the Oda continued in opposition to one another.

Following Kenshin’s demise, Nobunaga plotted a means to gain control of the Hokuriku region.  After the Battle of Arakawa in 1581, various retainers serving Nobunaga, including Terasaki Morinaga (the lord of Gankaiji Castle) and Ishiguro Naritsuna (the lord of Kifune Castle), were purged by Nobunaga for colluding with the Uesugi after having built the foundation for the Oda clan in the Hokuriku.

In the second month of 1582, the Oda army devastated the Kai-Takeda clan and, in the third month, the Oda surrounded Uozu Castle.  Meanwhile, Kojima Motoshige joined forces with Uesugi Kagekatsu to launch a surprise attack against Toyama Castle defended by Jinbō Nagazumi and captured the castle.  As a result, on 3/11 of Tenshō 10 (1582), Shibata Katsuie, Sassa Narimasa, Maeda Toshiie, and Sakuma Morimasa suspended their assault on Uozu Castle and Nobunaga had Katsuie and others attack and recapture Toyama Castle.  Thereafter, an Oda army of 40,000 men recommenced their assault on Uozu Castle while a garrison of 3,800 Uesugi troops holed-up in defense of the castle.

Hostilities

Under siege, Nakajō Kageyasu, the commanding officer of the Uesugi forces at the castle, urgently requested reinforcements from Uesugi Kagekatsu, but after eviscerating the Takeda, Oda forces remained stationed in Shinano Province adjacent to Echigo Province in addition to in Kōzuke.  Furthermore, Shibata Shigeie, the lord of Shibata Castle in Echigo, appeared poised to invade the territory of the Uesugi so Kagekatsu could not spare forces to support the defense of Uozu Castle.  Instead, he dispatched forces from Noto Province along with Saitō Tomonobu (the lord of Akata Castle) and Jōjō Masashige (the lord of Matsukura Castle).  On 5/4 of Tenshō 10 (1582), Kagekatsu departed from Kasugayama Castle with his own forces and, on 5/19, entered Tenjinyama Castle to the east of Uozu Castle, setting up a camp to serve as a rear guard.  Meanwhile, on 5/6, the Oda army occupied the outer citadel so Kagekatsu could not initiate a battle.

Mori Nagayoshi of Kaizu Castle in Shinano Province and Takigawa Kazumasu of Mayabashi Castle in Kōzuke Province prepared for an invasion of Echigo so, on 5/27, Kagekatsu decided to withdraw.  Thereafter, the Uesugi forces inside the castle continued to hold-out, as violent clashes persisted with the besieging army.  Three months after the start of hostilities, on 6/3, thirteen commanders who understood the castle would fall took their own lives together.  These included Sanponji Kagenaga, Yoshie Munenobu, Yoshie Kagesuke, Yoshie Sukekata, Terashima Nagasuke, Tadenuma Yasushige, Abe Masayoshi, Ishiguchi Hiromune, Wakabayashi Ienaga, Kameda Naganori, Fujimaru Katsutoshi, Nakajō Kageyasu, and Takenomata Yoshitsuna.  The castle fell and the Oda prevailed.  This occurred on the day after the unexpected death of Nobunaga, which news had already spread in the capital.

Aftermath

While the Oda forces momentarily basked in the joy of victory, unbeknownst to them, one day prior, their lord, Oda Nobunaga, died in a coup d’ètat launched by a senior retainer named Akechi Mitsuhide in an event known as the Honnō Temple Incident.  The news shook the clan and the troops scattered.  Once Uozu Castle was vacated, Suda Mitsuchika and other Uesugi forces entered and also recovered eastern portions of Etchū from which the Oda retreated.  At the ensuing Kiyosu Conference to decide the successor to Nobunaga, Sassa Narimasa obtained recognition of his rights to the territory of Etchū so the castle was attacked again.  Members of the Suda clan turned over the castle and pulled back to Kaizu Castle in Shinano.  Thereafter, during the Toyama Campaign, the Uesugi army combined with the Maeda to attack from eastern and western axes in another invasion of Etchū.  After the Toyama Campaign, Maeda Toshiie’s lineal heir, Maeda Toshinaga, received an increase to his fief of three of the four districts comprising the province, including the Tonami, Imizu, and Nei districts.  In 1595, his fief was further increased with the addition of the Niikawa District.  Aoyama Yoshitsugu who received castles from residents of Etchū associated with the Uesugi served as the chamberlain of Uozu Castle.  In the Edo period, owing to the mandate of the bakufu permitting only one castle per province, Uozu Castle was apparently abandoned.

Origins of some of the soldiers

Nakajō Kageyasu, Takenomata Yoshitsuna, and Yoshie Nobukage were all close associates of Uesugi Kenshin.  Fujimaru Katsutoshi, Kameda Naganori, and Wakabayashi Ienaga were originally provincial landowners and adherents of the Ikkō sect in Kaga Province.  After Kenshin’s invasion of Kaga, they became servants of the Uesugi.  Wakabayashi Ienaga is surmised to be a family member of Wakabayashi Nagato-no-kami, a leader of the uprisings when Kenshin invaded Kaga.  Sanponji Kagenaga was a member of the Uesugi family.  Yoshie Kagesuke does not appear on the record signed by the group of twelve from Uozu Castle but is deemed to have been killed the same day so is included in the group.

Anecdote

After Kagekatsu withdrew, thirteen commanders in the castle understood the fall of the castle was near, upon which they each attached wooden tags to their ears with their names and took their own lives together.