Iwasaki Castle

Iwasaki Castle is a historic hirayama-style hill castle situated in Nisshin, Aichi Prefecture, Japan. Originally constructed in the early 16th century during the turbulent Sengoku period, it was built by Oda Nobuhide to secure his eastern borders against the rival Imagawa clan. Its strategic location on the highway connecting Mikawa and Owari provinces made it a vital military asset. The fortress initially served as a support structure for Shobata Castle before changing hands in 1529 when Matsudaira Kiyoyasu seized it to establish a headquarters for the Matsudaira clan. Following Kiyoyasu's assassination, control passed to his retainer Niwa Ujikiyo, whose family governed the site for several decades.

The castle played a significant role in regional conflicts, most notably during the 1584 Battle of Iwasaki, which was part of the larger Battle of Komaki and Nagakute. Forces loyal to Toyotomi Hideyoshi besieged and captured the stronghold, inflicting heavy casualties on the defending Niwa garrison. After the decisive Battle of Sekigahara in 1600, the castle was abandoned and subsequently destroyed, leading the Niwa clan to relocate to new domains. For centuries, the site remained in ruins until archaeological efforts uncovered remnants of its original wells and turrets.

Today, Iwasaki Castle exists as a public historical park spanning two hectares. While much of the original structure lies in ruins, a ferro-concrete donjon was reconstructed in 1987 to serve as a local history museum. This modern building houses an extensive collection of artifacts, including traditional ceramics, samurai armor, and documents detailing the castle's rich past. The site remains open to visitors, offering a tangible connection to the region's feudal history and the prominent figures who once contested its grounds.