September 4, 1591

Kunohe rebellion

Kunohe Masazane surrenders Kunohe Castle

The promised mercy proved to be a trap: the garrison was killed, while Masazane was marched south for a later execution.

The fourth day of the ninth month, Tenshō 19

In 1591, on the fourth day of the ninth month, Kunohe Masazane and seven other commanders surrendered at Gamō Ujisato's camp outside Kunohe Castle in Mutsu Province.

Masazane accepted terms mediated by a priest associated with his family, after being promised favourable treatment or protection for those inside the castle.

The date usually printed as 4 September is that lunisolar date, not a Gregorian one; its proleptic Gregorian equivalent is 21 October 1591.

Who was outside the walls

Iwate Prefecture's account puts the besieging force at about 65,000 against roughly 5,000 defenders; a Heibonsha encyclopedia account reports about 60,000 besiegers.

This was a Toyotomi punitive force — an Ōshū re-pacification army, not an imperial one. Toyotomi Hidetsugu was named with Tokugawa Ieyasu among its commanders and Asano Nagamasa served as military inspector; Hideyoshi ordered the campaign but did not personally receive the surrender.

The terms are broken

After the surrender the promise was not honoured. The castle garrison was killed — a reported figure is 5,000 — while Masazane and the other leaders were taken south as prisoners and executed later.

The fall of Kunohe ended this major armed challenge to Toyotomi-backed Nanbu authority and was followed by a reorganization and destruction of many castles in the Nanbu domain.

The massacre is well established in reference accounts, though its most vivid details derive from later chronicles rather than the sparse contemporary evidence.

Sources

Researched 24 Aug 2026 7 sources not yet audited Traditional date

How this was checked

Researched from the web into a fact sheet and rewritten from that sheet. This article has not yet had an independent model audit. How the pipeline works →

Traditional date. Conventionally dated here; the research places it at 1591-10-21.

What the sources leave uncertain

The date commonly printed as 1591-09-04 is the fourth day of the ninth month in the contemporary Japanese lunisolar calendar, not Gregorian 4 September. Its proleptic Gregorian equivalent is 1591-10-21.
For the same reason, the stated opening date of 'March 13' corresponds to 1591-05-06 Gregorian.
Modern summaries differ on whether the final siege began on the first or second day of the ninth month, but they consistently place Masazane's surrender on the fourth day.
The massacre is well established in reference accounts, but vivid details such as every woman and child being locked in a particular bailey or a fire burning for three days derive from later chronicles rather than the sparse contemporary evidence.