The Battle of Arayama occurred in the sixth month of Tenshō 10 (1582) as a contest for control of Noto Province.  The battle was waged by the allied forces of Maeda Toshiie and Sakuma Morimasa against the allied forces of the Uesugi army led by Nukui Kagetaka and Miyake Nagamori (the Hatakeyama revival army) and the warrior monks of Mount Sekidō in Noto. 

The Nukui were kokujin, or provincial landowners, in Noto descended from the lineage of Fujiwara no Toshihito of the Fujiwara-Hokke and were backed by Uesugi Kagekatsu, an adopted son and heir of Uesugi Kenshin of Echigo province opposed to Nobunaga.

Prelude

On 6/2 of Tenshō 10 (1582), Oda Nobunaga died unexpectedly in a coup d’état led by one of his senior retainers, Akechi Mitsuhide, in an event known as the Honnō Temple Incident.  In the wake of the incident, the warrior monks of Mount Sekidō had been secretly plotting the recapture temple lands earlier seized by Nobunaga.  After the monks requested reinforcements from Uesugi Kagekatsu of Echigo Province, Nukui Kagetaka and Miyake Nagamori (siblings who were surviving retainers of the Hatakeyama clan protected by the Uesugi) departed.  At midnight on 6/23, the monks entered Arayama fortress and began to establish a stronghold.  Seizing the opportunity, they procured reinforcements from the Uesugi army and upon joining forces with Kagetaka, Nagamori, and former retainers of the Hatakeyama who returned from Echigo, rode the momentum in an effort to oust Maeda Toshiie.  Meanwhile, as a consequence of the coup that resulted in the death of Nobunaga, uprisings occurred in the former territory of the Takeda clan.  Takigawa Kazumasu and others to whom the power to govern had been delegated by Nobunaga fled one after another so the risk of an invasion of Echigo receded while Kagekatsu began an invasion in a bid to recapture Noto.

Course of events

For the Battle of Arayama, warrior monks on Mount Sekidō took advantage of the death of Oda Nobunaga to request Kagetaka and Nagamori who were in Echigo to deploy to Noto which then led to the instigation of a revolt against Maeda Toshiie.

Kagetaka and Nagamori aimed to reclaim Noto by force.  Together with Yusa Nagakazu, they led reinforcements from Uesugi Kagekatsu by sea, landing in the early morning of 6/23 (or in the seventh month) at the Himi-Mera Inlet and then climbed Mount Sekidō.  These forces then converged with warrior monks commanded by Hannya-in Kaison, Ōmiya-bō Ritsugen, Yamato-bō Kakushō, and Hinomiya-bō totaling 4,300 forces.

On 6/24, they endeavored to build a fort at Arayama Castle near Mount Sekidō and confronted Maeda Toshiie to whom the governance of Noto was delegated under the Oda administration.

Toshiie headed toward Mount Sekidō and sent letters to Sakuma Morimasa (the lord of Kanazawa Castle in Kaga Province) and Shibata Katsuie (the lord of Kita-no-shō Castle in Echizen Province) to urgently request their support.  Toshiie himself led a vanguard division of 3,000 forces and advanced toward Mount Sekidō.  These forces set-up an encampment at the Shiba Pass located in-between Mount Sekidō and Arayama and then launched a surprise attack against the allied forces of the Nukui and the Miyake who were en route to Arayama.  This resulted in the separation of the Nukui and Miyake forces between Mount Sekidō and Arayama.

Around this time, Morimasa led 2,500 soldiers and set-up a base in the village of Takahata in the southern foothills of Mount Sekidō,  but after receiving the news soon attacked Arayama Castle.  Kagetaka, Nagamori, and Nagakazu were all killed in battle.  Toshiie torched a temple building with over 50 monks from Iga and destroyed the Nukui army.

The heads of Kagetaka, Nagamori, and Nagakazu were left exposed to the elements at the Ōshiba Pass.  The next morning, amidst a dense fog, Toshiie launched an assault on Mount Sekidō by setting fire to the halls and monk’s quarters.  Caught off-guard, the warrior monks and Uesugi forces were decimated before they could arm themselves.  The whole mountain was engulfed in the fire.  After a contingent of 3,000 soldiers dispatched by Uesugi Kagekatsu as reinforcements observed the conflagration from around Abugashima, they withdrew to Echigo without attempting to intervene.

A letter from Morimasa dated 8/16 of Tenshō 10 (1582) states that at the Battle of Arayama, all of the members of the Nukui and Miyake clans were killed after being cornered in the fortress by Sakuma forces who came to the assistance of the Maeda from Kanazawa.

Aftermath

The Battle of Arayama between the allied forces of Maeda Toshiie and Sakuma Morimasa against the allied forces of Nukui Kagetaka, Miyake Nagamori, Yusa Nagakazu and the warrior monks of Mount Sekidō is not widely known, but all together it involved more than 10,000 men.  The burning on 7/26 of Mount Sekidō was on a scale comparable to the Burning of Mount Hei by Oda Nobunaga in 1571 and, as such, the Tenpeiji Temple was also turned to ashes.

The Arayama fortress was held by Sassa Narimasa after Nobunaga entrusted Etchū Province to him but, in 1584, Narimasa lost in battle to Maeda Toshiie and after the retreat by the defenders in the Sassa army, it became a key base for the Maeda clan.  The next year, after Narimasa surrendered to Toyotomi Hideyoshi at the Toyama Campaign, the western portion of Etchū came under the control of the Maeda clan while the Arayama fortress was abandoned.