Iwasaki Castle, often overlooked in history books and tourist guides, is located in modern-day Nisshin City, approximately 15 kilometers southeast of Nagoya City. Positioned on a hill, it offers clear views of the surrounding plain.
The castle is believed to have been built by Oda Nobuhide, father of Oda Nobunaga, in the early 16th century to protect his eastern borders and support his base at nearby Shobata Castle. In 1529, Matsudaira Kiyoyasu, Tokugawa Ieyasu’s grandfather, seized the castle by force. Six years later, Kiyoyasu was killed by one of his retainers during a misunderstanding, and his son, Matsudaira Hidetada (Ieyasu’s father), entrusted the castle to Niwa Ujikiyo.
Iwasaki Castle played a significant role in the Battle of Komaki and Nagakute in 1584. Ikeda Tsuneoki led the Toyotomi Hideyoshi forces against the Tokugawa-held castle. The Toyotomi strategy aimed to bypass Tokugawa lines and attack Ieyasu’s stronghold at Okazaki, making quick strikes on small castles along the way to confine them. However, at Iwasaki Castle, Ikeda’s forces were fired upon, and Tsuneoki himself was shot, falling from his horse. Enraged and humiliated, he commanded a full-scale assault. Despite a strong defense, the castle fell with heavy casualties, including over 300 dead. This delay allowed Ieyasu’s forces to catch up and defeat the Toyotomi at the Battle of Nagakute.
The Niwa clan held the castle for nearly 60 years until the Battle of Sekigahara in 1600, after which they were awarded a castle in present-day Toyota City, leading to Iwasaki’s abandonment. Reconstructed in concrete in 1987, the castle is now surrounded by two hectares of preserved parkland. Despite its visual appeal, the reconstruction is not historically accurate. An excavation revealed the remains of a well and a lookout tower. The structure below the keep now houses a museum dedicated to the history of the castle, the battle, and the Niwa clan.
See also
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Numata Castle
Numata Castle, located in Numata, northern Gunma Prefecture, Japan, has a rich and complex history. During the late Edo period, it served as the residence of the Toki clan, who ruled the Numata Domain. Over the centuries, the castle changed hands multiple times and was the site of significant battles during the Sengoku period.
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Iwabitsu Castle
Iwabitsu Castle is a yamashiro-style (mountain) castle located atop Mount Iwabitsu in Higashiagatsuma, Gunma Prefecture, Japan. Recognized for its historical significance, its ruins have been protected as a National Historic Site since 2019.
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Tsutsujigasaki Castle
Tsutsujigasaki Castle (Tsutsujigasaki Yakata) served as the fortified residence of the last three generations of the Takeda clan and is located in the heart of Kofu, Yamanashi Prefecture, Japan. Unlike traditional Japanese castles, it was not referred to as a "castle" in Japanese, as the Takeda clan famously believed in relying on their warriors as their true fortifications, stating, "Make men your castle, men your walls, men your moats." Designated a National Historic Site in 1938, the ruins are now open to the public and house the Takeda Shrine, a Shinto shrine dedicated to the deified spirits of the Takeda clan.
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Nagoya Castle
Nagoya Castle, originally built by the Owari Domain in 1612 during the Edo period, stands on the site of an earlier Oda clan castle from the Sengoku period. It became the centerpiece of Nagoya-juku, a significant castle town on the Minoji road, which connected two major Edo Five Routes: the Tokaido and the Nakasendo. In 1930, ownership of the castle was transferred to the city by the Imperial Household Ministry, establishing it as the focal point of modern Nagoya. Although partially destroyed in the Pacific War in 1945, the castle has undergone continuous restoration and preservation efforts since 1957.
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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.
