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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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.
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Uwajima Castle
Uwajima Castle, located in Uwajima City, Ehime Prefecture, Shikoku, is one of the 12 remaining Japanese castles with an original keep. Known for its small size, Uwajima Castle is relatively difficult to access, which means it is less frequented by tourists.
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Ueda Castle
Ueda Castle in Nagano Prefecture once stood prominently on a cliff overlooking the Saigawa River. Also known as Amagafuchi-Jo, Isesaki-Jo, Matsuo-Jo, and Sanada-Jo, it was built around 1583 by its first master, Sanada Masayuki. This sturdy yet small fortress cleverly utilized the surrounding natural defenses, including the river, steep rocky cliffs, the layout of the town below, and the strategically designed waterways to hinder attackers. Ueda Castle was fortified with seven defensive yagura (watchtowers) atop robust stone walls and had two large gates with watchtowers above them.
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Tsuyama Castle
Tsuyama Castle, located in Tsuyama City, Okayama Prefecture, is celebrated as one of Japan's top three major hilltop (Hirayama) castles, alongside Himeji and Matsuyama Castles. Originally, Tsuyama Castle comprised 77 structures, including the main keep, various yagura (watchtowers), gates, palaces, and living quarters. For comparison, Hiroshima Castle had 76 structures, and Himeji had 61. The first castle on this site was built in 1441 but was soon abandoned. The large-scale construction that we recognize today began in 1603 under the orders of Mori Tadamasa. The castle served as the administrative base for the Tsuyama Han daimyo, the Mori clan from 1603 to 1697, and the Matsudaira clan from 1698 to 1871.
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Tsu Castle
Tsu Castle, located in Tsu City, Mie Prefecture, was originally built by Hosono Fujiatsu in 1558 and was known as Anotsu Castle, named after the old region. The site was strategically chosen at the confluence of the Ano and Iwata Rivers, which naturally formed a moat around the castle, while the nearby port served as a vital trade route.
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Sasayama Castle
Tamba Sasayama Castle, also known as Sasayama or Kirigajo (Mist Castle), is a flatland castle (hira-jiro) situated on a gentle rise in the Tamba region of Hyogo Prefecture. It was constructed in 1608 as part of Tokugawa Ieyasu's strategy to prepare for an attack on Osaka, aiming to bring an end to the Toyotomi clan. Ieyasu ordered the castle's construction using the Tenka Bushin system, engaging 20 former enemy daimyo and their forces to complete the complex within six months. This system kept the former enemies close and preoccupied, financially straining them and limiting their capacity for further conflict. The stones used in Sasayama Castle feature engravings called kokumon, indicating who made each part of the walls and preventing theft by other lords' men.
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Sadowara Castle
Sadowara Castle in Miyazaki Prefecture was a mountaintop yamajiro castle, initially built by the Tajima clan during the Nanboku-Cho period (1334-1394). As was typical of castles from that era, Mt. Kakusho, the chosen mountain, was terraced to create various baileys, or kuruwa. While defensive structures were constructed at the top and around the mountain, the lord's main living quarters and administrative offices were situated at the mountain's base.
