When you cross Edo River on Keisei Line toward Chiba, you can see a huge plateau on the opposite bank.
This is the Kōnodai (国府台) plateau with its long history that not only encompasses a Sengoku-era castle but reaches back to Paleolithic settlements.
(This map bases on Tokyo Terrain Map powered by gridscapes.net)
The castle is said to have been constructed by Ōta Dōkan (太田道灌, 1432-1486) who established a temporary camp there. Kōnodai turned into an important strategic point between the provinces of Musashi and Shimōsa and into a battleground of the Kantō warlords.
Kōnodai was the scene of the first Battle of Kōnodai (1538) between Hōjō Ujitsuna (北条氏綱, 1487-1541), the son of the founder of the Late Hōjō clan, Hōjō Sōun, and Satomi Yoshitaka (里見義堯, 1507?-1574), who refused to submit to the overlordship of the Hōjō; although supported by the forces of Ashikaga Yoshiaki, Yoshitaka was defeated by Ujitsuna.
The second Battle of Kōnodai (1564) saw the same clans pitched against each other, with the sons of the commanders at the first battle facing each other: outnumbering the enemy 20,000 to 8,000 men, Hōjō Ujiyasu triumphed over Satomi Yoshihiro.
Parts of the original castle ground are now maintained as Satomi Park.
I walked up to Kōnodai Castle from Keisei Line Kōnodai Station. The castle had been abandoned in the Edo Period; in 1885, an army hospital was built in the southern stretch of the Kōnodai plateau. After World War II, a junior high school and a university were built nearby, literally turning the plateau into a school district. Passing the schools, I arrived at Satomi Park.
A castle monument is located in the southern part of the park.
Climbing up the slope in the north-west corner of the castle grounds, we can see earthworks and moats, giving the place a veritable "castle appearance".
From here, the City of Tōkyō can be seen on the opposite side of the river.
I can imagine that it was a very difficult location for the Hōjō army to attack, as the castle was situated on a 20-meter high plateau facing the river, while the defenders could easily spot and attack the enemy. The Hōjō however crushed the Satomi twice at Kōnodai. In the second battle, Yoshihiro was crushed when the Satomi held a premature victory party after fending off the attackers in the early stages of the conflict. We know that even a well-defended stronghold cannot make amends for the negligence of military leaders.
There is a memorial of the Satomi clan on the site of the former castle.
View of Kōnodai, No. 95 from One Hundred Famous Views of Edo; ukiyo-e by Utagawa Hiroshige (歌川 広重, 1797-1858).