Date: Eighth month of Tenshō 13 (1585)
Location: Toyama Castle in Etchū Province
Synopsis: With momentum from victory at the Battle of Komaki-Nagakute, Hashiba Hideyoshi launched attacks against those daimyō who continued to resist his rule. This included, among others, Sassa Narimasa in Etchū Province. After Hideyoshi sent a large army to lay siege to Toyama Castle, Narimasa lost the will to fight and instead surrendered to Hideyoshi who in turn spared him and his family.
Lord: Hashiba Hideyoshi
Commanders: Oda Nobukatsu, Oda Nobukane, Maeda Toshiie, Niwa Nagashige, Hosokawa Tadaoki, Kanamori Nagachika, Hachiya Yoritaka, Miyabe Keijun, Ikeda Terumasa, Inaba Norimichi, Mori Tadamasa, Gamō Ujisato, Kimura Shigekore, Nakamura Kazuuji, Horio Yoshiharu, Yamauchi Kazutoyo, Katō Mitsuyasu, Kuki Yoshitaka
The Toyama Campaign occurred in the eighth month of Tenshō 13 (1585). In this conflict, Hashiba Hideyoshi led a large army to surround and force the surrender of Sassa Narimasa at Toyama Castle in Etchū Province. This event is also known as the Conquest of Etchū.
As an outcome of the Battle of Komaki-Nagakute, Hideyoshi achieved a political victory, forcing the submission of Tokugawa Ieyasu. Hideyoshi then commenced attacks against the commanders aligned with the Tokugawa during that battle. In the sixth month of 1585, Hideyoshi sent his younger brother, Hashiba Hidenaga, as the commander-in-chief of Hashiba forces to attack Chōsokabe Motochika, the sengoku daimyō of Tosa Province in Shikoku. This is known as the Invasion of Shikoku. In the seventh month, Hideyoshi was appointed as the kanpaku, of Chief Advisor to the Emperor. Nevertheless, Sassa Narimasa continued to resist so, to eliminate him, Hideyoshi decided to have Oda Nobukatsu serve as the commander-in-chief of forces to invade Etchū. On 8/4, the division led by Nobukatsu departed from Kyōto and, on 8/6, Maeda forces camped at Torigoe in Kaga Province commenced fighting against the Sassa army. On 8/7, Hideyoshi himself departed the capital with additional forces.
Narimasa responded by having troops stations at thirty-six outlying bases across Etchū amass at Toyama Castle to prepare for an assault by Hashiba army. On 8/19, the Hashiba forces entered Etchū from Tsubata in Kaga and commenced attacks, setting fire to key locations in the province and laying siege to Toyama Castle. Uesugi Kagekatsu of neighboring Echigo Province acted in concert by sending troops to the border of Etchū. Hideyoshi then established a position on the Kurikara Pass (the site of a battle at the end of the twelfth century between the Shinano-Genji and Taira clans). This location allowed him to look down upon the border area of Kaga and Etchū provinces.
At the same time as this action, Hideyoshi had Kanamori Nagachika lead an offensive in neighboring Hida Province against allies of the Sassa, Anegakōji Yoritsuna and Uchigashima Ujimasa, to eliminate them. In the Conquest of Hida, the main division of the Kanamori forces led by Nagachika separated from the Hashiba army in Etchū while a detached division led by Nagachika’s adopted son, Kanamori Yoshishige, came from the direction of the Kanamori territory in Mino, enabling an invasion of Hida from the north and the south. With Narimasa unable to dispatch reinforcements, the Anegakōji were soon defeated, further isolating the Sassa in Etchū.
The Shinzū River, however, swelled, causing Toyama Castle to appear to float in the water, hindering a frontal assault. This would result in losses for the besieging forces. As a result, Hideyoshi sought to capture the castle with flooding. Meanwhile, during the siege, the Hashiba army confronted strong winds and rain, causing more trouble for them.
According to a letter dated 7/17 of Tenshō 13 (1585) from Hideyoshi to Katō Mitsuyasu, the Hashiba army comprised of five divisions in addition to naval forces and others totaling 57,300 men. The defenders in the Sassa army had 20,000 troops. In view of the disparity in the size of the armies, on 8/26, Narimasa proposed via Oda Nobukatsu to surrender. Narimasa then visited Hideyoshi at his encampment at the Kurikara Pass. On this occasion, Narimasa had shaved his head, wore the dress of a monk, and expressed his intention to obey Hideyoshi. Hideyoshi spared Narimasa and moved him and his wife and children to Ōsaka Castle. With the exception of the Niikawa District, all of Narimasa’s landholdings were seized. Thereafter, he served Hideyoshi as a member of the otogishū, or close associates of lords who engaged in conversation and similar activities. Later, Narimasa was transferred to Higo Province.
After the surrender by Narimasa, on 8/1, Hideyoshi entered Toyama Castle and proposed a meeting with Uesugi Kagekatsu of Echigo, but Kagekatsu did not come so, on 8/5, he demolished the castle and departed from Etchū.
Hideyoshi quickly withdrew his forces, proceeding to Kaga on 8/7, Echizen on 8/9, Sakamoto on 8/17, Kyōto on 8/24, and Ōsaka on 8/27. The expedition lasted a total of approximately 50 days.
Although this conflict did not feature a large battle, there are records of a nighttime attack by the Sassa forces against the second division led by Niwa Nagashige. After the event, retainers of the Maeda clan held memorial services for those killed in action so there appear to have at least been small-scale clashes.