Archaeologists in Osaka, Japan, believe to have found clues about an non-existent Sanada Maru fortress built and used by warlord Sanada Nobushige during the Siege of Osaka (1614-1615).
Sanada Maru was an Osaka Castle branch that projected southward from the “Sogamae” (general frame) moat, which defined the outermost contour of the Toyotomi clan’s castle. The discovery was made during the first excavation work in search of remains of the fortress in the Esashi-machi district of Osaka’s Tennoji Ward by a private group called Sanada Maru Excavation Promotion Council. Excavations revealed a layer of artificially filled earth at the site which might confirm the theory that the fortress was square-shaped and larger than previously thought. Warlord Sanada Yukimura known as Nobushige (1567?-1615) fought on the side of the Toyotomi clan during the 1614 Winter Campaign, one of the major battles in the Siege of Osaka. The warlord entrenched himself at Sanada Maru and repelled Tokugawa Shogunate forces, causing them major losses. After peace was made following the Winter Campaign, Sanada Maru was demolished.
Most available historical drawings represent the fortress in a semi-circular shape. The site is now largely the grounds of the Osaka Meisei Gakuen high school complex. Archaeologists excavated 70 square meters of land on the northern part of the plot that resembles the remains of a moat in an old cadastral map. A land plot on the southern area also remains depressed like a moat, indicating that the filled earth layer may have been part of earthwork surrounding the fortress. According to the experts it might have measured 300 meters in the east-west direction and 350 meters in the north-south direction, including the breadth of the moat.
(after Asahi Shimbun & Kazushige Kobayashi)