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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Okayama Castle
According to a number of accounts, the earliest fortifications on the site of present-day Okayama Castle appeared as early as the 14th century and were built by the Nawa clan. The Asahigawa River was used as a natural defensive barrier, protecting one side of the fortifications.
In the early 16th century, the Kanamitsu clan constructed a new castle here, which at the time was known as Ishiyama. In 1573, it came under the control of the Ukita clan, after which Ukita Naoie (1529–1582) launched large-scale reconstruction efforts. He did not live to see the work completed, and construction was continued by his son Hideie. -
Nagahama Castle
Hashiba, later known as Toyotomi Hideyoshi, received Odani Castle and the surrounding lands from Oda Nobunaga after the defeat of the Azai clan. However, Odani Castle was located high in the mountains, which made it poorly suited for the effective administration of the territory. For this reason, in 1575 Hideyoshi began constructing a new castle in the village of Imahama on the shore of Lake Biwa. Taking the character naga from Nobunaga’s name, he renamed both the village and the new castle Nagahama.
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Kokura Castle
Kokura Castle is traditionally considered to have been founded by Hosokawa Tadaoki (1563–1645), although by the time the Hosokawa clan came to control these lands, the fortification had already existed since at least 1569 and was most likely built by members of the Mori clan.
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Ikeda Castle
In 1334, Ikeda Noriyoshi built a small fort on this site, which over time was repeatedly expanded and rebuilt. During the Ōnin War of 1467–1477, the Ikeda clan supported the Western Coalition. As a result, Ikeda Castle was attacked and captured by the forces of the Eastern Coalition, but it was soon recaptured, allowing it to avoid serious destruction.
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Aizu-Wakamatsu Castle
Aizu-Wakamatsu is the most powerful and at the same time the oldest castle in the Tōhoku region in the north of Honshu Island. Its history begins in the 14th century and is closely connected with the Ashina clan, whose members claimed descent from the legendary Taira family.
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Maruoka Castle
Maruoka Castle is located in the central part of the former city of Maruoka, which is now part of the city of Sakai. This area lies in the northeastern part of Fukui Prefecture. The castle was built on the bank of the Kuzuryu River, on the side opposite Fukui City, which once served as the administrative center of the former Echizen Province. Thanks to its location, Maruoka held significant strategic importance, as it controlled two major routes at once: the Hokurikudo highway leading from Kaga Province and the Mino Kaido road connecting these lands with Mino Province.
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Marugame Castle
Marugame is part of the so-called “Authentic Dozen,” a group of twelve castles whose donjons have survived to the present day without major reconstructions since the Edo period.
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Iyo Matsuyama Castle
Historically, the center of Iyo Province—corresponding to today’s Ehime Prefecture on the island of Shikoku—was the city of Imabari, while the Matsuyama area was regarded as an agricultural hinterland with broad plains and low hills. During the Muromachi period, the central part of the province was governed by the Kano clan from Yuzuki Castle. With the onset of the Sengoku period, however, this clan lost its former influence and was forced to survive in the shadow of the more powerful Mori and Chōsokabe clans. After Toyotomi Hideyoshi’s forces conquered Shikoku in 1587, the northern part of Iyo Province was granted to Fukushima Masanori, one of the so-called “Seven Spears of Shizugatake.” In 1595, Masanori was transferred to Kiyosu Castle, and the lands around Matsuyama were given to another of the Seven Spears, Katō Yoshiaki, who received Masaki Castle and an income of 60,000 koku of rice.
