Sengoku Period: Japan's Age of Warring States

The Sengoku period is the century and a half when Japan had no functioning central government and its provinces fought each other more or less continuously. The name means "the age of the country at war", borrowed from the Warring States period of ancient China.

It is the era almost every image of the samurai comes from: castles, cavalry, matchlock guns, betrayals, and warlords with distinctive helmets. It is also better documented than most people expect, which means the difference between what happened and what was invented later can usually be established.

When did the Sengoku period begin and end?

The conventional start is 1467, when the Onin War broke out in Kyoto between two coalitions of great families. The war lasted ten years, wrecked the capital, and left the Ashikaga shogunate without the authority to govern beyond the city.

The end date is genuinely disputed, and different historians use different ones:

• 1568 — Oda Nobunaga marches into Kyoto and installs a shogun of his own choosing.
• 1573 — Nobunaga expels the last Ashikaga shogun, formally ending the shogunate.
• 1590 — Toyotomi Hideyoshi completes the unification at the Odawara Campaign.
• 1600 — Tokugawa Ieyasu wins at the Battle of Sekigahara.
• 1615 — the Siege of Osaka ends the last armed opposition. This site uses 1467–1615 as the outer range.

Why did Japan fall into civil war?

Medieval Japan was governed by a shogun in Kyoto who delegated provincial authority to a small number of great military families. Those families held their positions by appointment, and lived in the capital rather than in the provinces they governed. Real administration was done by deputies on the ground.

That arrangement was already brittle when the Onin War broke it. Once the central government could no longer enforce its appointments, the deputies simply kept the provinces they were running. Their retainers then did the same to them where they could. The era named the pattern gekokujo — "the lower overthrows the higher".

The result was a new kind of ruler: the daimyo, who held land because he could defend it, taxed it directly, wrote his own laws for it, and owed nothing to Kyoto but formal courtesy.

How did people actually fight?

The picture of individual mounted samurai duelling belongs to an earlier era. Sengoku warfare was conducted by large combined-arms armies: masses of ashigaru foot soldiers with long spears, bows, and — after firearms arrived through Tanegashima in 1543 — matchlock arquebuses, with mounted samurai as commanders and shock troops.

Most campaigns were about castles, supply and defection rather than pitched battles. Sieges were often settled by starvation or by paying someone inside to open a gate. When the great set-piece battles did happen — Battle of Nagashino, Battle of Sekigahara — they were frequently decided by who had already been bought before the fighting started.

The rise of Oda Nobunaga

For the first ninety years no one could translate regional dominance into national power. That changed with Nobunaga, a lord from a middling family in Owari who destroyed a much larger invading army at the Battle of Okehazama in 1560 and never stopped moving afterwards.

By 1573 he had expelled the last Ashikaga shogun, broken the militant Buddhist orders that had functioned as independent powers, and controlled the centre of the country. He was killed by his own general in 1582 at Honnoji Incident with the job perhaps two-thirds finished.

Hideyoshi's unification

Toyotomi Hideyoshi, born a commoner, avenged Nobunaga within two weeks at the Battle of Yamazaki, beat his rivals inside the Oda organisation, and finished the conquest of Japan at Odawara in 1590.

He then rebuilt the country's administration: nationwide land surveys, a sword hunt that disarmed the villages, and a legal separation between warriors and farmers. He also invaded Korea twice, disastrously. See Japanese Invasions of Korea (1592–1598).

Tokugawa Ieyasu and Sekigahara

Hideyoshi died in 1598 leaving a five-year-old heir. Two years later Tokugawa Ieyasu won the Battle of Sekigahara and in 1603 was appointed shogun. The government he founded lasted 265 years.

The final loose end was the Toyotomi house in Osaka, destroyed in 1615. After that Japan had no large-scale internal warfare until the 1860s.

Key terms

Japanese history writing in English is full of untranslated terms. These are the ones you will meet most often on this site.