Iwabitsu Castle

En un regard

Le château en bref

Clinging at around 590 m to the side of Mount Iwabitsu, an 802 m peak overlooking the left bank of the Agatsuma River, this castle covers some 136 ha, making it, according to Gunma Prefecture, the largest known medieval castle in its territory. Its originality lies in the combination of a defensive system with a terraced castle town, about 600 m long and set high up, a pairing considered unique at national level. The date of its founding remains unknown: the prefecture gives 1564 as its first written mention, while a specialist website suggests a 13th-century origin under the Agatsuma and a capture by Sanada Yukitaka in 1563, without citing a supporting document. A letter from Takeda Shingen, dated by estimate to 1565, does in any case mention troops sent there on Sanada's instructions. A Takeda outpost against the Uesugi, the site then became the centre from which the Sanada administered Agatsuma, on the route between Shinano and Kōzuke. The fall of the Takeda in 1582 left it with its most famous episode: Takeda Katsuyori is said to have been invited there but never to have reached it, and the Senryūin, on the southern slope, preserves the memory. Excavations in 2013-2015 and 2021 yielded ritual ceramics, Shinano-type cooking pots and a crucible bearing particles of gold. Today it is the vertical moats radiating down the slope that make the stronghold legible; the national notice considers it well preserved in its state of abandonment.