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.
The castle's design was crafted by Todo Takatora, a renowned castle architect, and construction was overseen by Ikeda Terumasa. The castle's wide moats and impressive ishigaki stone walls, along with its well-planned layout, are notable features. The three main gates are strategically positioned, and remnants of the Umadashi, special defensive ramparts outside the main gates, can still be seen. Although the castle has a tenshu-dai, or tower keep base, a keep was never constructed. One theory suggests that Ieyasu, fearing the castle's formidable design could be used against him, decided against building the keep. In reality, the plans were abandoned due to Ieyasu's urgency to start constructing Nagoya Castle. Similarly, the keep at Iga Ueno, another Todo Takatora design, was destroyed by a typhoon during construction, and Ieyasu, eager to eliminate the Toyotomi threat, canceled its rebuilding.
Most of Sasayama Castle was destroyed around 1871 at the end of the feudal period. However, the Dai O-shoin, the main palace building, remained intact until it was gutted by US aerial fire-bombing in 1944. The O-shoin was reconstructed in 2000, based on old photographs and the architecture of Nijo Palace in Kyoto, which itself was modeled after Nagoya Castle’s Honmaru Goten Palace. Interestingly, after completing Sasayama Castle, Ieyasu immediately ordered the same 20 daimyo to begin work on the larger, grander Nagoya Castle.
Parts of the original castle town still exist, and several traditional samurai houses have been preserved by the local government. Sasayama Castle is a fascinating site to explore, with ongoing preservation projects aimed at safeguarding the castle and its surrounding historical areas.
See also
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Unknown 1585 Letter Reveals How Toyotomi Hideyoshi Gave Yamato to His Brother and Consolidated Power in Japan
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The 16-Year-Old Samurai Who Crossed the Pacific and Discovered America in 1860
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Arato Castle
Arato Castle was built in 1524 by the Yamada clan under the orders of their overlord, Murakami, as a small mountain fort. Over time, it gained strategic importance and became a focal point in the conflict between two famous daimyō of the Sengoku period — Takeda Shingen and Murakami Yoshikiyo. This conflict turned the castle into one of the key fortifications in the struggle for control over Shinano Province.
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Tatsuno Castle
Tatsuno Castle is not a single fortification but rather a complex consisting of two parts: a mountain fortress located at the summit of Mount Keirozan and a flatland-mountain castle situated at its base. The mountain stronghold was built around 1499 by Akamatsu Murahide. During the Muromachi period, the Akamatsu clan was an influential family that, at the height of its power, controlled the provinces of Settsu, Harima, Bizen, and Mimasaka. Murahide’s ancestors were directly involved in the events of the Genkō War in the 14th century and in the subsequent establishment of the Ashikaga shogunate. However, by the 15th century, due to the process of gekokujō, the clan began to lose its position under pressure from rising families, including their former vassals—the Urakami and Bessho clans. In addition, the Akamatsu faced constant pressure from the Amago clan of Izumo Province.
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Takamatsu Castle
Takamatsu Castle was founded by Ikoma Chikamasa (1526–1603), who was appointed ruler of Takamatsu by Toyotomi Hideyoshi in 1587. The following year, Chikamasa began construction of the castle on the coast of the Inland Sea (Setonaikai), completing it by 1590.
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Sawayama Castle
During the Kamakura period, Sabo Tokitsuna, the sixth son of Sasaki Sadatsuna, built a fort on Mount Sawayama. This fort occupied a strategically important position because it allowed control over traffic along the important Tōsandō route, which was later known as Nakasendō. This road connected the capital, Kyoto, with the eastern regions of the country. Due to its location, the fortification held great military importance, and during periods of civil war it repeatedly became the site of fierce battles.
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Nadzima Castle
It is believed that the first structures on this site were built by Tachibana Akitoshi (?-1568), head of the Tachibana clan, a branch family of the Ōtomo clan, as auxiliary fortifications for Tachibanayama Castle. In 1587, Toyotomi Hideyoshi established control over the island of Kyushu and granted Chikuzen Province to Kobayakawa Takakage, one of the leading vassals of the Mori clan. Takakage began construction of a new castle on the site of the existing fortifications in 1588. The exact date of completion is unknown, but by the time the invasion of Korea began in 1592, the castle had already been finished, as records note that Toyotomi Hideyoshi stayed there overnight on his way to Hizen Nagoya Castle, which served as the headquarters of the invasion forces.
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Kubota Castle
The founder of the castle is considered to be Satake Yoshinobu (1570–1633). Yoshinobu was one of the six great generals of Toyotomi Hideyoshi. During the Odawara Campaign of 1590, he took part in the siege of Oshi Castle under the command of Ishida Mitsunari, with whom Yoshinobu developed a good relationship.
