Qualla: Iwatsuki Castle

Iwatsuki Castle: Introduction

Mon, 16 Feb 2026 00:00:00 GMT

Photo credit Saigen Jiro, CC0. In 1564, a father rode out to seek allies. While he was gone, his son opened the gates and handed everything to the enemy. That act of filial betrayal at Iwatsuki Castle was not even the most dramatic chapter in the fortress's history -- just another turn in a saga of shifting allegiances, massive sieges, and serial catastrophe that stretched across five centuries on the Kanto Plain. Built in the early Muromachi period by Narita Jikosai Tosho on a bend of the Arakawa River, the castle exploited the swampy lowlands of former Musashi Province to create a nearly impregnable defensive position. Water was both moat and ally here, with marshes guarding the west and south while the river shielded the north and east.

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Image: Saigen Jiro | CC0

Iwatsuki Castle: A Fortress Born from Swampland

Mon, 16 Feb 2026 00:00:00 GMT

Photo credit Fraxinus2, CC BY-SA 4.0. Iwatsuki Castle sat on the Kanto Plain near the northern edge of Musashi Province, surrounded by terrain that made conventional assault miserable. The main bailey, second enclosure, and third enclosure were ringed by extraordinarily wide swampy moats, turning the fortress into a ...

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Image: Fraxinus2 | CC BY-SA 4.0

Iwatsuki Castle: Betrayal, Siege, and the Hojo Juggernaut

Mon, 16 Feb 2026 00:00:00 GMT

Photo credit まも(Mamo), Public domain. The Ota clan had established firm control of Iwatsuki by 1522, but the Sengoku period rewarded flexibility over loyalty. After the Siege of Kawagoe Castle in 1546 shattered Uesugi power in the Kanto region, the Ota shifted their allegiance to the Odawara Hojo. When Uesugi Kenshin...

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Image: まも(Mamo) | Public domain

Iwatsuki Castle: Twenty Thousand Against Two Thousand

Mon, 16 Feb 2026 00:00:00 GMT

Photo credit Mimboo, CC BY-SA 3.0. The Hojo made Iwatsuki a family stronghold, installing a brother of Hojo Ujinao as castellan, followed by another brother, Ujifusa, in 1585. But in 1590, Toyotomi Hideyoshi launched his campaign against the Hojo at the Battle of Odawara and dispatched an army of 20,000 men toward...

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Image: Mimboo | CC BY-SA 3.0

Iwatsuki Castle: Fire, Ruin, and Cherry Blossoms

Mon, 16 Feb 2026 00:00:00 GMT

Photo credit tak1701d, Public domain. Fate dealt Iwatsuki its cruelest blows not through siege but through flame. In 1775, a catastrophic fire during the tenure of Ooka Tadayoshi consumed the castle and most of the surrounding town. The central donjon burned again in 1865, and Ooka Tadayuki, the last lord, simply lac...

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Image: tak1701d | Public domain

Iwatsuki Castle: The Swamp That Saved the Story

Mon, 16 Feb 2026 00:00:00 GMT

Photo credit Abasaa, Public domain. Today the park retains remnants of the original earthen fortifications and several sections of the wide moats that once made Iwatsuki so formidable. Two original castle gates, preserved by private owners over the generations, have been relocated to the park grounds. In spring, th...

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Image: Abasaa | Public domain