In 1600, just before the Battle of Sekigahara, Yamaguchi Munenaga, castellan of Daishoji Castle, belonged to Ishida Mitsunari's Western Army. He fiercely resisted an assault by Maeda Toshinaga's Eastern Army forces and died defending the castle. The site symbolizes the fighting on the Hokuriku front of the Western Army that Mitsunari organized.

Oda Nobunaga subjugated Kaga Province, once a stronghold of the Ikko-ikki, and placed it under the rule of his senior retainer Shibata Katsuie. Daishoji Castle was then held by one of Katsuie's subordinate generals, becoming part of Nobunaga's domain. It went on to guard the strategic border with Echizen Province, testifying to the expansion of Nobunaga's power into Kaga.

On August 3, 1600 (Keicho 5), as a prelude to the Battle of Sekigahara, Maeda Toshinaga attacked Daishoji Castle with roughly 20,000 troops. Castle lord Yamaguchi Munenaga, aligned with Ishida Mitsunari's western forces, held out with only about 500 men but the castle fell that same evening, and both Munenaga and his son Shuhiro took their own lives. The victory demonstrated Toshinaga's loyalty to the eastern army and secured the foundation of the Kaga million-koku domain.