Iwakura Castle was a hira-jiro, or flat-land castle, located in the plains that would become Iwakura City, Aichi Prefecture. At one time, it rivaled Kiyosu Castle in size and stature. Constructed in 1479, it covered an area of 900 meters north to south and 400 meters east to west. Two sets of moats encircled the castle: the outer moat, about 10 meters wide, and the inner moat, about 15 meters wide, separated by a 10-meter-wide strip. These moats surrounded the Honjo, or main castle precinct, which measured about 170 meters north to south and 90 meters east to west. To the north and directly east of the castle flowed the Gojo River.
The castle's Ote-mon, or main gates, faced southeast, with the rear gates to the north. Directly south and to the northeast were large areas, roughly the size of the central precinct, designated for samurai housing.
During the Sengoku period, Owari Province was ruled by two main factions of the Oda clan. The Iwakura Oda clan held the northern districts of Owari, while the Kiyosu Oda clan ruled the southern areas. The famed Oda Nobunaga belonged to the Shobata Oda clan, a branch of the Kiyosu Oda family.
Nobunaga increased his power by defeating and overtaking the Kiyosu Oda. In opposition, the Iwakura Oda formed an alliance with Nobunaga's brother, Nobuyuki. However, they were defeated by Nobunaga at the Battle of Ukino in 1558, after which Iwakura Castle was attacked.
In June 1558, Oda Nobunaga surrounded Iwakura Castle with palisades, set the castle town ablaze, and placed it under a siege that lasted for two to three months. During the ensuing battle, Yamauchi Moritoyo, a vassal of the Iwakura Oda, was killed. His son, Katsutoyo, was temporarily unemployed until joining Nobunaga’s forces around 1567, later becoming the master of Kakegawa and Kochi Castles.
Nobunaga continuously launched fire-arrows and fired rifles into the castle, employing various tactics to wear down the defenders. Eventually, the besieged Iwakura forces found it too difficult to hold the castle and decided to surrender. The defenders left and dispersed, and shortly thereafter, Nobunaga had the castle destroyed, returning to his castle at Kiyosu, having achieved the unification of Owari Province.
Unfortunately, nothing remains of Iwakura Castle except for a monument standing on the site of the rear gates to the main enclosure.
See also
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Wakayama Castle
Wakayama Castle was built in 1585, when Toyotomi Hideyoshi ordered his uterine brother, Hashiba (Toyotomi) Hidenaga, to construct a castle on the site of the recently captured Ota Castle. The purpose of this construction was to secure control over the likewise newly conquered Province of Kii. Following an already established tradition, Hidenaga entrusted the project to his castle-building expert, Todo Takatora. Takatora carefully inspected the future castle site, personally drew up several designs, created a model of the planned castle, and took part in the work of laying out the grounds (nawabari). For the construction he brought in more than 10,000 workers and completed the large-scale project within a single year, which was considered extremely fast by the standards of the time.
Toyama Castle
Toyama Castle is located almost in the very center of the former province of Etchū and is surrounded by a wide plain with a large number of rivers. The very first castle on the banks of the Jinzu River was built in 1543 by Jimbo Nagamoto. The Jimbo clan were vassals of the Hatakeyama clan and governed the western part of Etchū Province. The eastern part of the province belonged to their rivals, the Shiina clan, who were also Hatakeyama vassals. Beginning in the 15th century, the influence of the ancient Hatakeyama clan gradually weakened, and as a result, the Jimbo and the Shiina fought constant wars for control of the province. Meanwhile, the forces of the Ikkō-ikki movement periodically intervened, helping first one side and then the other.
Takada Castle
During the Sengoku period, the lands where Takada Castle would later be built were part of Echigo Province and were controlled by the Uesugi clan.
Kishiwada Castle
The celebrated 14th-century military commander Kusunoki Masashige (1294–1336), who owned extensive lands south of what is now the city of Osaka, ordered one of his vassals, Kishiwada Osamu, to build a fortified residence. This order was carried out around 1336. These fortifications became the first structures on the site of what would later become Kishiwada Castle. From the beginning, the castle stood in a strategically important location—roughly halfway between the cities of Wakayama and Osaka, south of the key port of Sakai. Because of this position, it changed hands several times during periods of warfare.
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.
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).
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.
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.
