Oda Nobunaga, as part of his “final solution” to the conflict with the Saitō clan, conceived the construction of a fort in the Sunomata area, which was intended to serve as a forward base for an attack on Inabayama Castle (later renamed Gifu). Sunomata was a swampy area located between Ogaki Castle, a stronghold of the Oda clan, and Inabayama, the main fortress of the Saitō clan. Earlier attempts to build fortifications in this area, carried out by Oda generals Sakuma Nobumori and Shibata Katsuie, had all ended in failure. After that, the task was entrusted to the young vassal Kinoshita Tokichirō, who later became known as Toyotomi Hideyoshi.
Hideyoshi approached the task in an unconventional and inventive way. He prepared a large supply of timber and prefabricated construction elements in advance, secretly floated them down the Sunomatagawa River, enlisted about two thousand workers, and erected the fortifications at the confluence of two rivers in an exceptionally short time. The speed of construction so astonished contemporaries that the castle came to be called Ichiyajō (“One-Night Castle”) or Sunomata Ichiyajō. In reality, it took Hideyoshi two to three days to assemble all the wooden structures and build the earthen fortifications. The rapid appearance of the fort within direct sight of Inabayama Castle was also intended to have a psychological effect by demoralizing the enemy. Hideyoshi later employed a similar tactic on a much larger scale during the siege of Odawara Castle, when he likewise secretly built Ishigaki Castle.
In fact, Sunomata Castle was an entrenched military camp protected by water-filled moats (mizubori), earthen walls (dobei), and wooden palisades (saku). After the successful siege of Inabayama Castle and the conquest of Mino Province, the Sunomata fortifications were dismantled.
In 1991, a donjon tower was built on the site of the former Sunomata Castle. This structure is a completely fictional “reconstruction,” since Sunomata never actually had a donjon. Ogaki Castle was used as the model for this building. Inside the tower there is a fairly good historical museum dedicated to the construction of the Sunomata fortifications and the confrontation between the Oda and Saitō clans.
See also
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Kaminoyama Castle
Kamino-yama Castle stood at the center of an important logistics hub, in the middle of the Yonezawa Plain, which served as the gateway to the western part of the Tohoku region. Roads connecting the Aizu, Fukushima, and Yamagata areas intersected here.
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Imabari Castle
Tōdō Takatora (1556–1630) served at different times as a vassal of several famous clans—Azai, Oda, Toyotomi, and Tokugawa. He took part in the Battle of Anegawa (1570), the Battle of Shizugatake (1583), the invasions of Kyushu and Korea, the Sekigahara campaign (1600), and the Siege of Osaka (1614–1615).
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Iwakuni Castle
Kikkawa Hiroie (1561–1625) was the grandson of the famous daimyo Mori Motonari and a vassal of the Mori clan. Under Mori Terumoto, he fought in both Korean campaigns and took part in the defense of Ulsan Castle. During the Battle of Sekigahara, Hiroie stood with his 3,000-man force on the side of the Western Coalition; however, even before the battle began, he sent Tokugawa Ieyasu a secret message stating that he did not intend to fight Tokugawa’s troops. As a result of his inaction, 15,000 soldiers under Mori Hidemoto were also unable to enter the battle, since Hiroie blocked their path.
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Gujo Hachiman Castle
Gujo Hachiman Castle is located on 350-meter Mount Hachiman, near the confluence of the Yoshidagawa and Kodaragava rivers, and not far from the Nagaragawa River. During the Sengoku period, this area was of great strategic importance: it stood at a key crossroads of routes connecting Mino Province in the south with the Sea of Japan in the north, and Hida Province in the east with Echizen Province in the west.
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Amagasaki Castle
The founding year of Amagasaki Castle is traditionally considered to be 1617, when Toda Ujikané built his castle here, making it the administrative center of the Amagasaki Domain. However, as early as the Sengoku period, a fortress built by the Hosokawa clan already stood on this site. After the fall of Itami Castle in 1579, Araki Murashige—formerly a vassal of Oda Nobunaga who had rebelled against him—fled to this earlier castle.
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Hiroshima Castle
Mōri Terumoto (1553–1625) was the grandson and rightful heir of the renowned Mōri Motonari. When Terumoto became the head of the Mōri clan in 1571, he inherited vast territories covering a large part of the San’in and San’yō regions in western Honshū. In addition, the Mōri clan possessed the largest and most technologically advanced naval fleet of its time.
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Fukuyama Castle
After the defeat of Toyotomi Hideyori’s supporters in the Osaka Campaigns of 1614–1615, many clans in Japan still remained not fully loyal to the Tokugawa shogunate, especially in the western Chūgoku region. Mizuno Katsunari (1564–1651), a cousin of Tokugawa Ieyasu, became the first of the Tokugawa house’s close retainers, the so-called fudai daimyō, to be relocated to this strategically important area.
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Tiba Castle
The founder of the Chiba clan is considered to be Chiba Tsunesige (1083–1180), who in 1126 moved his residence to the Inohana area and built a strongly fortified stronghold there. Although Tsunesige himself came from the Taira clan, the Chiba clan later supported Minamoto no Yoritomo, the future founder of the first shogunate.
