INTERACTIVE BATTLE
Battle of Yamanaka Castle
29 March 1590 · Yamanaka Castle
The Toyotomi army attacked Yamanaka Castle, a Later Hōjō stronghold guarding the route to Odawara, and captured it within half a day.
Background
Yamanaka Castle was a mountain fortress that the Later Hōjō had constructed to defend the western approaches to Odawara, with surviving remains showing advanced fortification techniques such as board-like trenches and ridge trenches. As Hideyoshi's Odawara campaign approached, the garrison rushed to reinforce auxiliary positions including Daisaki Demaru, but the Toyotomi forces chose a direct assault rather than bypassing the castle.
Outcome
On March 29 of the eighteenth year of Tenshō, the Toyotomi launched their assault from the direction of Daisaki Demaru and the West Tower, and captured the castle in about half a day. Castle lord Matsuda Yasunaga and others from the Later Hōjō side died, as did Ichiyanagi Naoesue and others fighting for the Toyotomi.
Course of the battle
1 29 March 1590
Toyotomi forces launch a general assault
Advancing toward Odawara, Toyotomi forces attacked Yamanaka Castle from several directions. The Later Hojo had been strengthening this western approach through Hakone.
Sources12345·Certainty: High
2 29 March 1590
Fighting spreads from the outworks to the main enclosure
Fighting spread from the Daisaki outwork and western sector toward the inner enclosures. Matsuda Yasunaga on the Hojo side and Hitotsuyanagi Naosue among the attackers were killed.
Sources12345·Certainty: High
3 The same day
Yamanaka Castle falls
Yamanaka Castle fell quickly and the Toyotomi army continued across Hakone toward Odawara. Exact troop totals, duration, and routes assigned to each contingent remain uncertain.
Points of debate
Troop totals, duration, and attack routes are disputed.
Sources12345·Certainty: High
Historical significance
This assault marked the beginning of a large-scale multi-front campaign striking not only at Odawara Castle but simultaneously at satellite fortresses such as Nirayama, Hachigata, and Hachiōji. It initiated the step-by-step collapse of the Later Hōjō defensive network.
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Key figures
豊臣氏
2
Tōkaidō regional commander
Is said to have participated in the Yamanaka Castle assault as one of the Toyotomi generals mobilized in the Tōkaidō region.
Sources1·Certainty: Medium
Tōkaidō regional commander
Is said to have participated in the Yamanaka Castle assault as one of the Toyotomi generals mobilized in the Tōkaidō region.
Sources1·Certainty: Medium
Other events of 1590
Sources consulted
- 三島市「山中城跡」
- 三島市郷土資料館「山中城の合戦後の勘兵衛」
- 三島市「山中城跡（国指定文化財「史跡」）」
- 三島市「戦国・安土桃山時代」
- 静岡県「しずおか文化財ナビ 山中城跡」
The numbers in the text refer to the list above. Certainty indicates how far a statement is supported by the cited sources; it does not refer to the precision of the coordinates or the dating.
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