The Battle of Nanao Castle

The Battle of Nanao Castle—Kenshin's Pacification of Noto and the Pinnacle of Hokuriku Control

The siege of Nanao Castle, conducted from Tenshō 4 (1576) to Tenshō 5 (1577), was a nearly year-long siege orchestrated by Uesugi Kenshin, the "God of War" of Echigo, to establish his control over Noto Province (present-day Noto Peninsula region, Ishikawa Prefecture). Nanao Castle was the primary stronghold of the shugo daimyō Hatakeyama clan of Noto Province, built atop Kojo-yama (Old Castle Mountain, 300 meters high) overlooking Nanao Bay, and was the most imposing and fortified castle in Noto in terms of both scale and strength.

By conquering this castle, Kenshin ushered the struggle for hegemony in Hokuriku into a new phase, bringing vast territories spanning Noto, Etchu, and Kaga under his control. Shortly after Nanao Castle's fall, Kenshin achieved a historic victory at the Battle of Tetori River, defeating a large force under Oda Nobunaga and marking the military zenith of his career.

The Decline of the Noto Hatakeyama and Uesugi Kenshin's Intervention

The Hatakeyama clan, shugo daimyō of Noto Province, was a cadet branch of the Hatakeyama, one of the Three Administrators (Kanrei) of the Muromachi shogunate, and had long ruled Noto as a distinguished house. However, as the Sengoku period progressed, the Noto Hatakeyama fell into repeated factional strife, with powerful retainers such as Yusa Tsugumitsu and other senior officials wielding considerable influence, and the authority of the clan's nominal leaders became greatly weakened.

Kenshin's active intervention in Noto began around Tenshō 2 (1574). After consolidating control of Etchu Province (present-day Toyama Prefecture), Kenshin sought to expand further west into Noto, Kaga, and Echizen. Members of the Hatakeyama household called for Kenshin's aid, providing him justification to deepen his involvement in Noto.

In spring of Tenshō 4 (1576), Kenshin entered Noto from Etchu and began the siege of Nanao Castle. However, the castle's commanding terrain made swift conquest difficult. Kenshin lifted the siege temporarily and returned to Etchu, then launched a full-scale investment again in autumn of the same year.

Nearly a Year of Siege—Plague and Treachery Bring Down the Castle

The intensive siege that began in autumn of Tenshō 4 (1576) lasted roughly one year. Nanao Castle, protected by its commanding terrain and amply provisioned with food, water, and weapons, proved nearly impossible to take by direct assault. The Kenshin forces pursued a blockade strategy, cutting off supply lines to starve the garrison (siege by starvation).

As the siege dragged on, tragedy unfolded within the castle walls. In summer of Tenshō 5 (1577), plague—variously identified as dysentery or smallpox—swept through Nanao Castle, felling the samurai and soldiers who formed its main garrison. Castle lord Hatakeyama Haruo-maru and numerous retainers and troops succumbed to the plague. The defensive capacity collapsed rapidly, and the castle fell into a state of despair.

In this darkening hour, a traitor emerged from within the castle. Yusa Tsugumitsu, a senior Hatakeyama retainer, secretly conspired with Kenshin and in September of Tenshō 5 opened the castle's rear gate (karamoto), admitting the Uesugi forces. The castle crumbled from within, and Hatakeyama Haruo-maru surrendered or took his own life (accounts vary).

When Kenshin learned of Nanao Castle's fall, a celebrated Chinese poem attributed to him is preserved. Beginning with "Frost fills the military encampment, autumn's clarity reigns; rows of geese pass through the moon's third watch," this poem is said to have been composed by Kenshin at his command post overlooking Nanao Castle as the nearly year-long siege concluded, and has endured as a testament to the warrior-poet's cultivated sensibilities and refinement.

To the Battle of Tetori River—Kenshin's Triumph Over Nobunaga's Forces at His Peak

Shortly after Nanao Castle's fall, on the 23rd day of the ninth month of Tenshō 5 (1577, by lunar reckoning), Kenshin and his forces clashed with the Oda army at Tetori River (present-day Ishikawa Prefecture). At the Battle of Tetori River, Kenshin's Uesugi forces achieved a great victory against a massive Oda contingent—reportedly 40,000 to 50,000 strong—commanded by Shibata Katsuie, Takigawa Kazuaki, and Toyotomi Hideyoshi.

The Oda had marched to relieve Nanao Castle, only to find it already fallen. Retreating forces fell upon the Uesugi in pursuit at the river crossing and suffered devastating losses. This battle is regarded by later military historians as one of the few instances in which Kenshin demonstrated clear superiority over the military might of the Oda-Tokugawa alliance (though the battle's scale and circumstances remain debated among scholars on the basis of source materials).

Kenshin subsequently withdrew to Echigo while continuing his Hokuriku administrative efforts. However, in the third month of Tenshō 6 (1578), Kenshin collapsed suddenly at Kasugayama Castle (present-day Joetsu City, Niigata Prefecture), succumbing to a cerebral stroke. He was 49. The Battle of Nanao Castle and the Battle of Tetori River became his final, resplendent military victories.

Connection to Blades—Noto Smiths and Kenshin's Swords

In considering the connection between the Battle of Nanao Castle and blades, one must first note Noto Province's blade culture. The Noto Peninsula has long been renowned as a center of blade production, and particularly Noto's smiths forged works in a distinctive style known as Noto-mono (Noto works). During the era of the Noto Hatakeyama, numerous artisans gathered in Nanao Castle town, and the production of blades and military equipment flourished. Kenshin's conquest of Nanao Castle meant that this reservoir of Noto craftsmanship and cultural legacy passed into Uesugi dominion.

Uesugi Kenshin himself was celebrated among Sengoku daimyō as a connoisseur and collector of fine blades. Among the masterworks he possessed was a celebrated sword, "Kenshin Kagemitsu" (a work by Kagemitsu of Osafune, Bizen, of the late Kamakura period), which Kenshin particularly treasured. After his death, these blades passed to his successor Uesugi Kagekatsu and remained heirlooms of the Uesugi house across generations.

Among the spoils Kenshin seized at Nanao Castle were surely swords, armor, and treasures accumulated by the Hatakeyama across generations. As a cadet line of the Three Administrators, the Noto Hatakeyama possessed a storied collection: blades transmitted from Kyoto and fine works by Noto smiths. Kenshin transported these treasures to Echigo, enriching the Uesugi repositories.

The Chinese poem Kenshin composed upon Nanao Castle's fall reveals his dual nature as warrior and scholar. For Kenshin, blades transcended mere weapons; they were spiritual emblems of the samurai code and objects of artistic appreciation. His reverence for the sword was bound to the spirit of Bishamonten (the protector deity of Kenshin's devotion), manifesting as deep respect for the blade as an instrument of righteous warfare.

Historical Significance of the Battle of Nanao Castle—Kenshin's Hokuriku Supremacy and Uesugi Expansion

The Battle of Nanao Castle stands as one of Uesugi Kenshin's paramount achievements in Hokuriku consolidation. By this victory, Kenshin pacified Noto Province and, combined with Etchu and Kaga, effectively placed vast territories spanning three provinces of Hokuriku under his authority. His dominion now spanned from the eastern Kanto Kanrei region into the three provinces of Hokuriku—a vast realm that posed an undeniable threat to Oda Nobunaga.

Had Kenshin lived beyond his death in Tenshō 6 (1578), his ultimate ambition—invasion from Hokuriku into the Home Provinces—might have materialized. The Battle of Nanao Castle was the last great stride toward that goal. After Kenshin's death, Hokuriku descended into renewed turmoil, ultimately falling under Oda-Toyotomi rule following campaigns by Shibata Katsuie and Toyotomi Hideyoshi.

Today, the ruins of Nanao Castle (Kojo-yama) in Nanao City, Ishikawa Prefecture, are preserved as a historic site. From the summit, one may gaze across Nanao Bay and appreciate the castle's former strategic importance. A stone marker bearing Kenshin's attributed poem stands as a testament to the battle's significance and welcomes many visitors as a historic site of the Battle of Nanao Castle. Nanao Castle ruins stand as a valued archive of Noto's heritage and culture, and the strife of the Hokuriku region during the Sengoku era.