Ōnin War

The Ōnin War was a civil war in Japan that lasted from 1467 to 1477, fought mostly in and around the capital, Kyoto. A quarrel between the shogun's deputy Hosokawa Katsumoto and the powerful provincial lord Yamana Sōzen, tangled up with disputed successions in the shogun's family and in leading clans, drew great lords from across the country into a decade of fighting. It left Kyoto in ruins, gutted the authority of the Ashikaga shoguns and opened the long era of civil war known as the Sengoku period.

The war is often blamed on a dispute over who would follow the eighth shogun, Ashikaga Yoshimasa. In 1464, having no son, he persuaded his younger brother Yoshimi to leave the monastery and named him heir. In 1465, however, Yoshimasa's wife Hino Tomiko gave birth to a son, Yoshihisa, and sought support for his claim. Hosokawa backed Yoshimi; Yamana sided with Tomiko and her son.

The succession was only one cause. Real power in the Ashikaga shogunate rested with a council of great lords, and the deaths of several of them, together with intrigue at court, had left the government unstable. From 1441 crowds repeatedly demanded debt cancellations and attacked the sake brewers and warehouses on whose taxes the shogunate depended. At the same time, rival heirs were fighting over the leadership of the Hatakeyama and Shiba clans. According to the most widely held view, the main cause was the feud between Hatakeyama Yoshinari and Hatakeyama Masanaga.

By 1467 the lords had formed two coalitions: an Eastern Army under Hosokawa, said to number about 85,000, and a Western Army under Yamana of about 80,000. Fighting broke out in Kyoto that year as rival mansions were burned. Hundreds of large buildings were destroyed in the summer, and Hosokawa was soon hemmed into the north-east of the city while Yamana held the south and west. Ōuchi Masahiro brought 20,000 men to reinforce Yamana in September, and in November the Western Army captured the great temple of Shōkoku-ji.

The war then settled into a stalemate. The two armies faced each other across a trench some three metres deep and six metres wide, while temples such as Tenryū-ji burned. Loyalties shifted strangely. Yoshimi went over to Yamana's side, and in 1469 the shogun named his son Yoshihisa as heir, so the two armies effectively swapped candidates. Yoshimasa, meanwhile, devoted himself to poetry and to planning the Silver Pavilion.

Both Yamana and Hosokawa died in 1473, yet the fighting dragged on. Branded rebels by the court, the Western Army gradually lost heart, and on 17 December 1477 Ōuchi Masahiro burned his quarter of Kyoto and withdrew. Neither side had achieved its aims. Much of the capital had been destroyed, and local tradition holds that its residents still meant the Ōnin War when they spoke of "the war" well into the 20th century.

The war gave tacit licence to private warfare across Japan. In Yamashiro Province the two Hatakeyama factions fought each other to a standstill until, in 1485, local warriors and peasants rose, expelled both armies and by 1486 had set up their own provincial government. In Kaga Province, followers of the Ikkō sect of Jōdo Shinshū Buddhism, the Ikkō-ikki, overthrew the governor Togashi Masachika in 1488 and took control. Such upheavals are often described as gekokujō, "the low overcoming the high".

After the war the Ashikaga shoguns became puppets of the Hosokawa, who dominated the shogunate until 1558, when they were themselves betrayed by their vassals, the Miyoshi. The Ōuchi fell to their former vassal Mōri Motonari in 1551. Across the country, vassals turned on their lords and succession disputes drew in outsiders. New warlords rose in this turmoil, among them Oda Nobunaga, who won a victory at Okehazama in 1560, and by the close of the Warring States era a mere dozen or so great warlord houses survived. In 1921 the historian Naitō Konan argued that the period around the Ōnin War was the most important in Japanese history, and that understanding modern Japan required little knowledge of what came before it.

Our 1492 map shows Japan after the war, and the 1530 map shows the country in its Warring States era.