Siege of Mount Hiei (1571): Nobunaga Destroys Enryaku-ji

The Siege of Mount Hiei was the attack by the Japanese warlord Oda Nobunaga on the great Buddhist monastery of Enryaku-ji, north-east of Kyoto, on 29 September 1571. His troops burned the town of Sakamoto and the temple halls and killed thousands of monks and residents. The assault broke the military power of one of Japan’s oldest religious institutions and became the most notorious act of Nobunaga’s career.

Background: a monastery with an army

Enryaku-ji was founded in 788 by the monk Saicho, who brought the Tendai school of Buddhism from China. Set on Mount Hiei, which rises above Kyoto on one side and Lake Biwa on the other, it was meant to protect the new capital of Heian-kyo from evil influences coming from the north-east.

Over the following centuries Enryaku-ji became a great landowner. It controlled estates, toll barriers and the trading town of Sakamoto on the lakeshore, and it maintained armed followers, often called sohei or “warrior monks”. These forces repeatedly marched into Kyoto to press the court with demands. Earlier rulers had clashed with the monastery, and the warlord Hosokawa Masamoto had burned parts of it in 1499.

By the 1560s Japan was in the late Sengoku (“Warring States”) period. Oda Nobunaga, lord of Owari province, had entered Kyoto in 1568 and was trying to impose his authority on central Japan.

Causes of the attack

In 1570 Nobunaga fought a coalition led by Asai Nagamasa of northern Omi and Asakura Yoshikage of Echizen. In the autumn of that year their armies withdrew onto Mount Hiei, and the monks of Enryaku-ji gave them shelter and supplies. Nobunaga could not dislodge them from the steep mountain.

According to the chronicle of his retainer Ota Gyuichi, Nobunaga offered the monks a choice: join his side, or at least stay neutral, and their lands would be restored to them. If they refused, he warned, he would burn the mountain. The monks did not accept, and the standoff ended only with a truce at the end of 1570.

For Nobunaga, the monastery was not simply a religious centre but a rival power that had sided with his enemies and controlled a strategic route between Kyoto and the east. Destroying it would remove a threat close to the capital and send a message to other armed religious groups, such as the Ikko-ikki leagues of the Jodo Shinshu sect.

What happened on 29 September 1571

In September 1571 Nobunaga’s army, often estimated at around 30,000 men, surrounded Mount Hiei. On the 12th day of the 9th month in the Japanese calendar, 29 September by the Western calendar, his troops first set fire to Sakamoto and then advanced up the slopes.

Temple buildings, including the Konpon Chudo, the main hall, were burned. Contemporary accounts describe soldiers killing monks, lay people, women and children without distinction. Ota Gyuichi wrote of thousands of bodies, and the diary of the courtier Yamashina Tokitsugu recorded a figure of 3,000 to 4,000 dead.

Modern historians accept that the killing was extensive, but they give a range. Estimates usually fall between about 1,500 and 4,000 victims.

Key people

• Oda Nobunaga (1534–1582): the warlord who ordered the attack. His chroniclers justified it by accusing the monks of breaking their vows and taking sides in war.
• Akechi Mitsuhide: one of Nobunaga’s commanders in the operation. He was rewarded with lands around Sakamoto, where he built Sakamoto Castle.
• Asai Nagamasa and Asakura Yoshikage: Nobunaga’s enemies, whose alliance with the monks triggered the attack. Both were destroyed in 1573.

Archaeology and debate

Since the late 20th century, excavations on Mount Hiei have found fewer burned layers dating from 1571 than the written accounts suggest. Some archaeologists argue that many summit buildings were already ruined or abandoned before the attack, and that the worst burning and killing took place in Sakamoto and on the lower slopes.

This does not deny the massacre, which several independent sources describe. It does suggest that the image of the entire mountain going up in flames may be exaggerated.

Consequences

Enryaku-ji lost its lands and its armed forces. It never again acted as an independent military power. The attack also showed other religious institutions what resistance might cost; Nobunaga’s long war against the Ishiyama Hongan-ji in Osaka ended with its surrender in 1580.

Mitsuhide’s new base at Sakamoto made him one of Nobunaga’s most important generals. Eleven years later he turned against his lord in the Honno-ji Incident. Nobunaga’s successor Toyotomi Hideyoshi allowed rebuilding to begin in the 1580s, and the Tokugawa shoguns continued it. The present Konpon Chudo was completed in 1642.

Timeline

• 788: Saicho founds a temple on Mount Hiei, the origin of Enryaku-ji.
• 1499: Hosokawa Masamoto burns parts of the monastery.
• 1568, autumn: Oda Nobunaga enters Kyoto.
• 1570, autumn: The armies of Asai and Asakura take refuge on Mount Hiei with the monks’ support.
• 1570, end of year: A truce ends the standoff.
• 1571, 29 September: Nobunaga’s forces burn Sakamoto and Enryaku-ji.
• 1573: Nobunaga destroys the Asakura and Asai.
• 1642: The rebuilt Konpon Chudo is completed.

Why it matters

The destruction of Enryaku-ji marked the end of the era when great monasteries could field armies and defy secular rulers in central Japan. It became a defining image of Nobunaga as a ruthless unifier, and it helped prepare the way for the centralised order later built by Hideyoshi and the Tokugawa.