The Siege of Suemori Castle occurred on 9/9 of Tenshō 12 (1584) at Suemori Castle in Hōdatsu-Shimizu in the Hakui District of Noto Province.  The conflict was waged between the Maeda army led by Maeda Toshiie and the Sassa army led by Sassa Narimasa.

In 1584, Hashiba Hideyoshi engaged in a standoff at Komaki-Nagakute against the allied forces of Oda Nobukatsu and Tokugawa Ieyasu.  Acting in concert with the allied army of the Oda and Tokugawa, on 8/28, Sassa Narimasa of Etchū Province launched a surprise attack against Asahiyama Castle defended by Maeda Toshiie who was on the side of the Hashiba clan.  Murai Nagayori, a retainer of the Maeda family, repelled the attackers.

On 9/9, Narimasa, aiming to divide Toshiie’s territory comprised of Kaga and Noto provinces, traversed Mount Hōdatsu and set-up a position at the Tsuboyama fortress from which to surround Suemori Castle with a total of 15,000 troops.  He had these troops guard against reinforcements from Toshiie and further assigned Jinbō Ujiharu to keep watch at Kitakawashiri.

On 9/10, upon the outbreak of hostilities, Okumura Nagatomi and Senjū Norimasa, led the garrison of 300 soldiers to resist the besieging forces.  In the initial stages, the Sassa army gained the upper hand, killing a commander at the castle known as Doi Tsugushige (the younger brother of Doi Chikazane), making their hold on the castle precarious.  Despite a breach of the outer citadel by the attackers, the remaining commanders and their garrison held-out until the arrival of reinforcements from Toshiie, repelling the Sassa forces.  During the battle, Nagatomi’s wife, Tsune, walked around the castle holding a naginata, or glaive, distributing watery cooked rice and attending to the injured soldiers, raising their spirits.

Upon receiving an urgent report while at Kanazawa Castle, Toshiie deployed with a contingent of 2,500 soldiers.  Guided by a peasant named Sakurai Saburōzaemon from the village of Takamatsu, the Maeda forces followed along the coastal road that was not well-guarded by the Sassa army.  After traversing Kitakawashiri, the forces arrived at Imahama.

At dawn on 9/11, the Maeda forces launched an all-out assault from the rear of the Sassa army, defeating them.  Each camp lost over 750 soldiers in the conflict.

Narimasa withdrew and headed toward Etchū Province but along the way occupied Torigoe Castle in the Kahoku District of Kaga which had been abandoned.  Thereafter, he strengthened his defenses and assumed a defensive posture.  Toshiie succeeded in defending his territory and cooperated with Hideyoshi who had secured a political victory at the Battle of Komaki-Nagakute and pressed the offensive.  This is known as the Toyama Campaign.