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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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.
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Kavanhoe Castle
Kawanoe Castle is located on the small Wasi-yama hill near the port area of the Kawanoe district in the city of Shikokuchuo, occupying a central position along the northern coast of Shikoku Island. Kawanoe was also known as Butsuden Castle. The term “butsuden” in Japan refers to temple halls, and for this reason it is believed that a Buddhist temple once stood on the site before the castle was built. Due to its location at the junction of four provinces on Shikoku Island, Kawanoe held significant strategic importance and was repeatedly targeted by rival forces seeking military control over the region.
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Yokote Castle
The founder of the castle is considered to be the Onodera clan. The Onodera were originally a minor clan from Shimotsuke Province and served Minamoto no Yoritomo (1147–1199), the founder of the first shogunate. The Onodera distinguished themselves in battle against the Fujiwara clan of the Ōshū branch and were rewarded with lands around Yokote. Around the 14th century, the Onodera moved to Yokote as their permanent residence. Their original stronghold was Numadate Castle, but after a series of clashes with the powerful Nambu clan, they relocated their base to the site of present-day Yokote Castle. It was likely during this time that the first fortifications appeared at the castle.
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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.
