Ōnin War

What Happened

The Ōnin War was a civil war fought in Japan from 1467 to 1477, during the Muromachi period. It began as a dispute between two powerful men — Hosokawa Katsumoto, a high official of the shogunate, and Yamana Sōzen, a regional lord — and escalated into a nationwide conflict that drew in the Ashikaga shogunate and a large number of daimyō (大名, feudal lords) from many regions.

The fighting was concentrated in Yamashiro Province, the home province of the capital, Kyoto. The war's named engagements include the Battle of Goryō, the Battle of Higashi-iwakura, the Siege of Wakae Castle, the Battle of Nishinooka, the Battle of Kamigyō, and the Battle of Shōkoku-ji. Kyoto itself was the principal battleground, and the city suffered extensive destruction over the decade of fighting.

The conflict involved the Hosokawa clan, the Yamana clan, the Shiba clan, the Hatakeyama clan, and the Ōuchi clan, alongside the Ikkō-ikki and the Ikkō-shū, armed leagues of Buddhist devotees. The war ended in 1477, having lasted eleven years.

Background

By the mid-fifteenth century the Ashikaga shogunate, the military government that had ruled Japan since 1336, was losing its grip on the great warrior houses. Two of those houses in particular, the Hosokawa and the Yamana, had grown strong enough to compete directly for influence over the shogunate itself.

The immediate trigger was a succession dispute. Hosokawa Katsumoto backed one candidate for the shogunal succession; Yamana Sōzen backed another. Around this central quarrel clustered a set of older feuds among the great families — the Shiba, the Hatakeyama, and others — each of which had its own internal split over inheritance. What might have remained a court intrigue instead pulled in armed houses across the country, because each faction could call on allies and clients far from the capital.

The result was that a dispute at the top of the political order became a general war. The Ashikaga shogunate, rather than suppressing the conflict, was itself divided and drawn into it.

Why It Mattered

The Ōnin War is conventionally treated as the event that opened the Sengoku period, the "Warring States period" — a long, drawn-out struggle in which individual daimyō fought to dominate the whole of Japan. The authority of the Ashikaga shogunate never recovered from the war.

The destruction of Kyoto was itself decisive. The capital was not merely the seat of government but the centre of the country's courtly and monastic institutions, and a decade of fighting there hollowed out the old order. Power shifted outward, to regional lords who could raise and hold armies of their own.

The war also demonstrated that the great houses could be broken from within. The Shiba and Hatakeyama, both drawn into the fighting through their own succession disputes, were among the houses whose internal divisions the war exposed and deepened.

The Name in Japanese

The Japanese name is 応仁の乱.

• Kana reading: おうにんのらん
• Romaji: Ōnin no Ran

Broken down character by character:

• 応 — read here as ō. It carries the sense of "to respond," "to answer," or "to comply."
• 仁 — read here as nin. It means "benevolence," "humanity," or "virtue" — one of the central concepts of Confucian thought.
• の — read no. This is the possessive particle, linking the name that precedes it to the noun that follows. It works like the English "of."
• 乱 — read here as ran. It means "rebellion," "revolt," "disturbance," or "war." In Japanese historical writing, ran is the standard word attached to the name of a civil conflict or uprising.

So the whole name means, roughly, "the Ōnin disturbance" or "the Ōnin rebellion."

The first two characters, 応仁, are not descriptive words here — they are an era name, or nengō (年号, ねんごう). Japanese eras were named in pairs of auspicious characters, and 応仁 was the era during which the war began. The war takes its name from the era in which it started, not from the year it ended: it concluded during the succeeding Bunmei era. This is why the conflict is sometimes also called the Ōnin-Bunmei war.

The pattern is worth remembering, because it recurs constantly in Japanese history. A war, a revolt, or a major upheaval is often named after the era in which it broke out, with の乱 (no ran) appended. Recognising 応仁 as an era name rather than as a description is the key to reading the title correctly.

Key Figures

Hosokawa Katsumoto — the high shogunate official whose dispute with Yamana Sōzen set the war in motion. He led the Hosokawa faction.

Yamana Sōzen — the regional lord who opposed Hosokawa Katsumoto. The quarrel between these two men was the conflict's immediate cause.

Ashikaga Yoshihisa — an Ashikaga shogunal figure connected to the war.

The war also drew in the Hosokawa clan, the Yamana clan, the Shiba clan, the Hatakeyama clan, and the Ōuchi clan, as well as the Ikkō-ikki and the Ikkō-shū. The involvement of so many houses — each with its own grievances and its own internal divisions — is what turned a dispute between two men into a nationwide war.