Siege of Oshi

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Siege of Oshi
Part of Supremacy of Toyotomi Hideyoshi
Oshi-jo fukugen 001.jpg
Oshi Castle
Date 1590
Location Musashi Province
36°8′13.74″N 139°27′10.36″E / 36.1371500°N 139.4528778°E / 36.1371500; 139.4528778Coordinates: 36°8′13.74″N 139°27′10.36″E / 36.1371500°N 139.4528778°E / 36.1371500; 139.4528778
Result Toyotomi victory
Hōjō forces Toyotomi forces
Commanders and leaders
Narita Nagachika
Ishida Mitsunari
3000 23,000

The 1590 Siege of Oshi (忍城の戦い?, Oshi-jō no tatakai) was one of many battles in Toyotomi Hideyoshi's campaigns against the Hōjō clan during Japan's Sengoku period.

Oshi Castle was a stronghold of the Narita clan in north-central Musashi Province. The Narita were originally vassals of the Ogigayatsu Uesugi clan and under the leadership of Narita Akiyasu completed Oshi Castle around 1479. The castle was built on a small elevation near the Tone River and made use of marshes and swamplands in its surroundings as part of its defenses, It was regarded as one of the seven most important strongholds of the Kantō region.

The Narita changed their allegiance to the Odawara Hōjō clan in 1546 following the defeat of the Uesugi at the Siege of Kawagoe Castle. In 1560, Uesugi Kenshin invaded the area in support of Uesugi Norimasa, the official Kanto kanrei causing Narita Nagayasu to waiver in his ties to the Odawara Hōjō. However, after a quarrel with Kenshin, the enraged Nagamasa returned to the Odawara Hōjō side, and the castle town was burned down by Kenshin in 1574. In the 1590 Siege of Odawara, Toyotomi Hideyoshi dispatched his senior retainer Ishida Mitsunari on an expedition to reduce the outlying castles still loyal to the Odawara Hōjō clan. Three days after capturing Tatebayashi Castle, Ishida’s forces of 23,000 troops arrived at Oshi. At Oshi, the clan leader, Narita Ujinaga was at Odawara with the bulk of his forces, leaving his home castle defended by only 619 samurai and 2000 local conscripts, led by his daughter Kaihime and younger brother Narita Ujichika.

In the Siege of Oshi, the castle’s held off numerous attacks, including a copy-cat effort to flood the defenders out patterned after Hideyoshi’s famous Siege of Takamatsu. Despite Mitsunari’s impressive construction of 28 kilometers of dikes and torrential rains, the castle still held for over a month and its defenders only after word that their lord had been defeated at Odawara.

From this battle, Oshi Castle gained fame as the “floating castle”, but more importantly, Mitsunari emerged with a sullied reputation as a poor commander, which affected his subsequently ability to gain the loyalty of powerful daimyo after the death of Toyotomi Hideyoshi and contributed to his defeat at the 1600 Battle of Sekigahara

In popular culture[edit]

See also[edit]


  • Turnbull, Stephen (1998). 'The Samurai Sourcebook'. London: Cassell & Co.