Senmi Castle
Senmijō is a yamajiro (mountaintop castle) ruin in the north of Miasa Township, Ômachi Municipality. Senmijō, deep within the mountainous interior of Shinano, is a barely visited and underexplored site. Indeed, I was able to make a tremendous discovery at this ruin, namely a large trench complex whi
.jpg)
History
Senmijō was first built by the Obinata Clan, vassals of the Murakami Clan, to protect the mountain passes which led to their territory from the west. On the otherside of the mountains was the territory of the Nishina Clan. This was during the first half of the 16th century.
In 1552, Takeda forces invaded Azumi County, and Yamagata Masakage attacked Senmijō. The fierce battle saw castellan Obinata Nagatatsu slain, and the castle fall under Takeda control. In subsequent years the castle changed hands due to in-fighting within the Obinata Clan. The clan was split between supporting the Takeda and resisting, and this dispute became an all out civil war within the clan (see Fumimichi Castle). But in 1555 the pro-Takeda faction of the Obinata took back the castle from the rebels.
Many defeated clans in Nagano, like the Murakami Clan, fled to Echigo to be with Uesugi Kenshin following the advance of Takeda Shingen. However, the Kai-Takeda Clan met its final demise in 1582 (see Taira-yashiki), and thereafter Uesugi Kagekatsu took back territory in Shinano, including Senmijō which became a frontline castle against the resurgent Ogasawara Clan (former official governors of Shinano Province).
Ogasawara Sadayoshi ordered the Nishina Army to attack Senmijō in 1584, and they successfully conquered the castle, only to see it fall back into Uesugi Kagekatsu's hands a couple of months later. The Nishina attacked once more that year, but this time failed to capture the mountain fortress. The following year, 1585, Ogasawara Sadayoshi successfully conquered Senmijō, and that year installed Futatsugi Morimasa as castellan, who rebuilt the castle.
In 1590, following the fall of Odawara to Toyotomi Hideyoshi which cemented his position as undisputed leader of Japan, Uesugi Kagekatsu, defying the general trend toward peace that Toyotomi-kampku (regent) was trying to encourage, brazenly attacked Ogasawara lands, and re-captured Senmijō in the autumn. The kampaku was not best pleased, and ordered Uesugi Kagekatsu to retreat, which he did. Thereafter Ishikawa Iemasa was appointed castellan of Senmijō.
Field Notes
Senmijō is a yamajiro (mountaintop castle) ruin in the north of Miasa Township, Ômachi Municipality. Senmijō, deep within the mountainous interior of Shinano, is a barely visited and underexplored site. Indeed, I was able to make a tremendous discovery at this ruin, namely a large trench complex which has gone unidentified by Yogo-sensei and Ranmaru-sensei, the castle-bloggers whose maps I was using to navigate the site. The spirit of adventure and thrill of discovery is very much alive in this quiet place.
Senmijō features horikiri (trenches), dorui (earthen ramparts), tatebori (climing moats), kuruwa (baileys) and other earthwork ruins. Ranmaru divides the castle complex into three fortresses: an upper A-Fort, a lower B-Fort, and a detached C-Fort. Indeed, the site is quite expansive.
Whilst searching for the route to the C-Fort annex, I noticed a tatebori climbing the mountainside beside the trail. I climbed up this chute (keeping pace with a lizard scurrying at my feet), and discovered a large horikiri located between the A and C forts. This trench is not depicted on any maps of the castle I have seen, and so I'm happy to claim it as my own discovery.
"ART's Trench (please indulge me)" is not some ambiguous divot, but a very well formed and preserved trench complex, with an impressive depth of about 2 m on the descending side, and some 5m on the rising side of the ridge. It is situated on an otherwise unworked ridge section with no baileys attached, which is curious. The structure is of a central trench segment with a steep climbing section to the south, and a careening section to the north where it joins up with a creek. This creek seems to have been augmented as a defensive line to stop lateral movement on the mountainside, and there is a 'U'-shaped egress at the bottom of this chute. If I had stumbled into this falling section I would've no doubt been catapulted off the mountain like an awry pinball.
There is an embankment overlooking the trench on the descending side. It has some gnarly old trees and clumps of grass, and to me was a small oasis from whence I admired the beauty of the sculpted earth. Below the embankment I could only see the tops of trees. Later, retracing my steps after climbing up the scarp to A-Fort, I realised that the path I was on when I noticed the tatebori section of the trench is the path descending to the C-Fort from B-Fort, and that beneath the trench and berm is a cliff of sheer, smooth rock. This was confounding. Why did the castle-builders dig a deep trench along a ridge which was impossible to reach from below?
I'm not one for making up my own theories, amateur as I am, but I got to thinking how C-Fort was accessed originally from the rest of the castle. It was likely from C-Fort that the rest of the castle was accessed, but was as it by that tiny path which now exists going from B-Fort, or were there large ascending bridges, perhaps hikibashi (draw-bridges), connecting C-Fort with A-Fort over cliff and trench? If the enemy breached C-Fort and the bridges were withdrawn or collapsed, it would be extremely difficult for them to then enter the rest of the castle. This is just my outlandish idea, but how else can we account for this large trench here?
Gallery
.jpg)
.jpg)
.jpg)
.jpg)
.jpg)
.jpg)
.jpg)
| Castle Profile | |
|---|---|
| English Name | Senmi Castle |
| Japanese Name | 千見城 |
| Founder | Obinata Clan |
| Year Founded | Early 16th Century |
| Castle Type | Mountaintop |
| Castle Condition | Ruins only |
| Historical Period | Pre Edo Period |
| Artifacts | Dorui, Horikiri, Kuruwa, &c. |
| Features | trenches |
| Visitor Information | |
| Access | Shinano-Ômachi Station on the Ôito Line; rental e-bike |
| Hours | 24/7 free; mountain |
| Time Required | 150 minutes |
| URL | Castle Website |
| Location | Ômachi, Nagano Prefecture |
| Coordinates | 36.60735, 137.91629 |
|
|
|
| Admin | |
| Added to Jcastle | 2023 |
| Contributor | ART |
| Admin Year Visited | Viewer Contributed |
| Friends of JCastle | |
| Kojō Seisuiki | |
| Ranmaru | |
| Yogo | |
