Yamanaka Castle, established by Hojo Ujiyasu in the 1560s, is located in what is now eastern Mishima, Shizuoka Prefecture. This castle served as the first line of western defense for the main Hojo Castle at Odawara. Carved into the side of a 586-meter-high mountain, Yamanaka Castle was strategically positioned along the Tokaido Highway, offering superb views of nearby Mt. Fuji, the ocean, and the road leading to Odawara.
The castle featured five baileys: the Honmaru, Ni-no-Maru, Kita-no-Maru, Nishi-no-Maru, and the Daisaki-de-Maru. These compounds were fortified with well-defended gates, log palisades, and wooden walls equipped with gun and arrow slits. Intricately designed dry moats and steep slopes further protected the castle. Notably, Yamanaka Castle’s unique Shoji-bori and Une-bori moats, which are waffle-shaped with narrow ridges surrounding square depressions, can still be seen and appreciated today. These dry moats were necessary as sourcing and maintaining water at the top of the mountain was impractical.
In 1587, as Toyotomi Hideyoshi neared the complete unification of Japan, he set his sights on the Hojo clan, who had not yet submitted to his rule. As he raised large armies against them, the Hojo fortified their smaller outlying castles, including Yamanaka, which was commanded by Hojo Ujikatsu and supported by around 4,000 samurai. However, these fortifications were incomplete when Hideyoshi made his move in 1590. The Toyotomi army, numbering around 67,000, vastly outnumbered the Hojo defenders at a ratio of 16 to 1. Despite this, the Hojo troops fought valiantly, inflicting heavy losses on the Toyotomi forces. The battle, which lasted barely half a day, or according to some accounts, as little as two hours, ended in the deaths of most defenders and the destruction of the castle. Hojo Ujikatsu and his top generals fled to assist in the defense of Odawara Castle. This battle marked the first skirmish in the Siege of Odawara, leading to the downfall of the Hojo clan.
Declared a National Historic Site in 1934, Yamanaka Castle had reverted to forest, prompting preservation projects to restore its remains. Although no structures remain, the distinctive Shoji-bori and Une-bori moat systems are still visible and appreciated. These moats, with their narrow ridges, ensured attackers could only cross in single file, making them easy targets for defenders. The ridges likely featured wooden spikes and tied ropes to further hinder attackers. In 2006, Yamanaka Castle was listed among the Top 100 Castles of Japan.
See also
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Matsushiro Castle
Matsushiro Castle, originally known as Kaizu Castle, is located in what was once Matsushiro town, now part of Nagano City. The site is recognized as a National Historic Site of Japan. Situated on the northern Shinano flatlands between the Chikuma River and a former riverbed that serves as a natural outer moat to the north, the castle and its surrounding town were prone to flooding due to their location.
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Fushimi Castle
Fushimi Castle, also known as Momoyama Castle or Fushimi-Momoyama Castle, is located in Fushimi Ward, Kyoto. Originally built by Toyotomi Hideyoshi between 1592 and 1594 as his retirement residence, the castle was destroyed by the 1596 Keichō–Fushimi earthquake and later rebuilt. However, it was demolished again in 1623, and its site now houses the tomb of Emperor Meiji. A replica of the castle was constructed nearby in 1964.
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Odawara Castle
Odawara Castle, located in the city of Odawara, Kanagawa Prefecture, Japan, is a reconstructed historical site with roots dating back to the Kamakura period (1185–1333). The current donjon (main keep) was rebuilt using reinforced concrete in 1960 on the stone foundation of the original structure, which was dismantled between 1870 and 1872 during the Meiji Restoration.
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Shinpu Castle
Shinpu Castle was a Japanese hirayama-style fortress from the Sengoku period, situated in what is now Nirasaki, Yamanashi Prefecture. It served as the main stronghold of warlord Takeda Katsuyori. Designated as a National Historic Site in 1973, the castle occupies a strategic position on a mountain with steep cliffs, overlooking the Kamanashi River to the west of Kofu, where Takeda Shingen’s Tsutsujigasaki Castle once stood.
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Takato Castle
Takato Castle, located in the city of Ina in southern Nagano Prefecture, Japan, was a notable stronghold during the Sengoku period. By the end of the Edo period, it was the residence of a cadet branch of the Naito clan, the daimyo of the Takato Domain. Also known as Kabuto Castle, it was originally constructed in the 16th century and is now mostly in ruins.
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Takatenjin Castle
Takatenjin Castle was a yamashiro-style fortress from Japan's Sengoku period, situated in the Kamihijikata and Shimohijikata districts of Kakegawa, Shizuoka Prefecture. Designated a National Historic Site in 1975, with an expanded protected area in 2007, its ruins remain a significant historical landmark.
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Yoshida Castle
Yoshida Castle is renowned worldwide, particularly through the intricate woodblock prints by Edo Period artist Hiroshige. His famous series, depicting the 53 stages of the Tokaido—the historic route between Kyoto and Edo (modern-day Tokyo)—includes the 34th print, which shows workmen repairing a castle overlooking a wooden bridge crossing a wide river. This scene captures the Toyokawa River at Toyohashi in southeast Aichi Prefecture, and the castle is Yoshida Castle.
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Yamato Koriyama Castle
The impressive ruins of Koriyama Castle sit atop a small hill, surrounded by two rivers. The strategic positioning and strong layout of the castle served it well through the final years of the Sengoku period and the peaceful days of the Edo period.
