The siege of Mount Hiei was a battle of the Sengoku period of Japan fought between Oda Nobunaga and the sōhei (warrior monks) of the monasteries of Mount Hiei near Kyoto on September 30, 1571. It is said that Oda Nobunaga killed all the monks, scholars, priests, and children that lived on the mountain in this battle. However, recent excavations have pointed out that many of the facilities may have been abolished before this and the destruction was less than some historical sources indicate.
Background
The trigger for the conflict was Nobunaga’s extortion of military funds from the territory of Mount Hiei. In 1569 Jiin-hosou, the lord of the mountain, worked in the imperial court. Because of this, the imperial court requested funds for the restoration of the temple territory, but Nobunaga refused. Nobunaga went on to win the Battle of Anegawa on July 30, 1570. However in the battles of Noda Castle and Fukushima Castle on August 26, 1570, the allied forces of Azai Nagamasa and Asakura Yoshikage were victorious. The Asai-Asakura forces stood on Mt. Hiei and were besieged by Nobunaga’s forces (Siege of Shiga), but they were reconciled by the mediation of Emperor Ogimachi.
In addition to the Azai-Asakura forces, Rokkaku Yoshikata was active as a guerrilla in the southern part of Omi and Koka, and the Miyoshi clan was also aiming to regain Kyoto by suppressing Settsu and Kawachi. In addition, Kōsa, who led the Ikkō-ikki issued orders to the Settsu, Kawachi, Omi, Ise, and the Owari monks who were under Nobunaga’s thumb. On January 2, 1571, Kinoshita Hideyoshi, the owner of Yokoyama Castle, was ordered to block the sea and land routes leading from Osaka to Echizen. The purpose was to cut off contact between Ishiyama Hongan-ji Temple, the Azai-Asakura alliance, and Rokkaku Yoshikata. Nobunaga ordered his men to interrogate and kill any suspicious people. The blockade of traffic at this time seems to have been quite strict, as stated in the "Kenkenki", a diary written by Monzeki Hironori.
In February of the same year, the isolated Sawayama Castle surrendered, and the castle owner Isono Kazumasa evacuated, so Nobunaga assigned Niwa Nagahide as the castle owner and secured a passage from Gifu Castle to the lakeside plain. In May, the Azai army teamed up with the Ikko-ikki to re-enter the Ane River and attack Hidemura Hori. Kinoshita Hideyoshi helped Hori and fought hard, and the Ikko-Ikki and Azai forces were defeated. In the same month, Nobunaga burned down the villages that participated in the Sieges of Nagashima in Ise. He then attacked Odani Castle, which was the residence of Nagamasa on August 18. On September 1, he ordered Shibata Katsuie and Sakuma Nobumori to siege Shimura Castle and Kogawa Castle, which were the bases of Rokkaku Yoshikata and Omi's Ikko-ikki. At Shimura Castle, there were 670 head hunters, and it is believed that they were almost wiped out. Seeing that, the soldiers of Ogawa Castle surrendered. Kanegamori Castle was also sieged, but it fell without a big battle.
On September 29, Nobunaga marched around Sakamoto and Mitsui-ji Temple, and set up his headquarters at Yamaoka Keigaku's mansion.
The lord of Mt. Hiei at that time was Kakujo , the younger brother of Emperor Ogimachi . Mt. Hiei was the intersection of Hokuriku Road and Togoku Road for those aiming for Kyoto, and there were many shrines on the mountain, making it a strategically important base capable of holding tens of thousands of soldiers.
In the previous offensive and defensive battle of Mt. Hiei, the Mt. Hiei side refused the peace that promised to return the temple territory that Nobunaga extorted, and also supported the Asai-Asakura Alliance. Nobunaga is said to have considered completely destroying the military base. Due to Nobunaga being surrounded by enemy forces, the neutralization of Mt. Hiei was considered to be an important issue for breaking the front line.
The Enryaku-ji pleaded for the suspension of the attack by giving 300 gold coins, along with 200 more from nearby Katata, but Nobunaga refused. The monks and soldiers who lived around Sakamoto gathered at Nemoto Nakado on the mountaintop, and the residents of Sakamoto and their wives and children also fled toward the mountain.