In 1426 Matsudaira Yasuchika and Matsudaira Nobumitsu vanquished Nakane Daizen and Lord Nobumitsu constructed Iwazujō to secure the territory won. He made it his main base in 1429. A series of fortifications and residences were constructed around the base of the castle, known as the ‘Seven Castles of Iwazu’, after seven Matsudaira castellans, including Chikanori, Mitsunori, Nobumori, Nagakatsu, and Chikakatsu. Other castellans from the surrounding area were also brought to Iwazu, and these included lords Norimoto, (Anshō) Chikatada, Moriie, (Makiuchi) Chikatada, Tomosuke, Mitsuchika, Mitsuo, and Chikayo. By the way it is said that Nobumitsu had 48 sons (he presumably also had daughters). There are nine fortification sites in the Iwazu group, but after excluding Iwazu Castle itself, Daizen Castle and Daizen West Castle were probably considered to be one castle.
In 1465 the area was rocked by the Nukata County Revolt, centred on Iguchijō to the south of Iwazujō. The Matsudaira won territory for suppressing the revolt. The Iwazu-Matsudaira used Iwazujō as their main base until conquering more territory and moving to Anshōjō in 1471. In 1584, Tokugawa Ieyasu renovated Iwazujō during the Komaki-Nagakute campaign, and the ruins date to this time.
Iwazujō is an okajiro (hilltop castle) type yamajiro (mountaintop castle) in the Iwazu Township of Okazaki Municipality, north of downtown Okazaki. It is the main castle of a cluster of fortification sites in Iwazu, known as the ‘seven castles of Iwazu’, though I counted nine sites in total. There are substantial ruins at only two of the sites, Iwazujō and Iwazushinjō; very little to see at two more, Iwazu-Inojō and Iwazu-Kibirajō, and nothing castle-related to see at the others, those having been developed over with housing and such. Iwazujō itself, however, is a fantastic site, a nice, compact earthworks castle ruin for castle fans to appreciate. The site is now mostly a bamboo grove but the castle precincts are well maintained by a group of dedicated volunteers (their website: http://www.iwazujo.com/).
Iwazujō features kuruwa (baileys), dorui (earthen ramparts), karabori (dry moats), dobashi (earthen bridges) and other bridge remains. I entered the site via the second karabori where somebody has constructed what looks like a railroad made of bamboo. There is a cart on the track. It runs much of the length of the second karabori and I don’t know its purpose, but it looked fun. The dorui of the second and third baileys rise above the karabori. There is a depression in the ramparts, and opposite at a sort of diagonal angle there is a platform on the other side of the moat. It is thought that a wooden bridge was built here to grant access to the castle.
The second and third baileys have tall, thick dorui protecting them. These berms are thick enough to have hosted towers. Between these baileys and the main bailey is the first karabori. The first karabori is spanned by a beautiful earthen bridge (I find earthen bridges beautiful), which the ramparts of the first bailey loom above. On either side of the dobashi there are deep dry moats.
The main bailey of Iwazujō is spacious. In the middle there is a small information board; leaflets are kept in a plastic jar there. The dorui remains in the south because this is where the karabori was dug, and the excavated earth was heaped up into ramparts for the bailey. The other sides of the main bailey are protected by terraced baileys which create a giant stairway out of the hilltop. Exploring this site was very satisfying.
Other sites in this fortification complex are as follows:
|Matsudaira Nobumitsu; Tokugawa Ieyasu
|Local Historic Site
|Pre Edo Period
|Karabori, Kuruwa, Dobashi, Dorui, &c.
|Nearest Station is Kitanomasuzuka Station on the Aichi Loop Line
|24/7 free; park
|Okazaki, Aichi Prefecture
|35° 0' 17.42" N, 137° 10' 27.88" E
|Added to Jcastle
|Admin Year Visited
|Friends of JCastle
|Jōkaku Shashin Kiroku