Japan Castle Explorer: Tendo Castle -One-by-one attack to circular alliance-

Tendo Castle

-Individual attack to circular alliance-

Overview

Name: Tendo castle (Tendo-jo)
Alias:
Place: Tendo Tendo city, Yamagata
Type: Mountain Castle
Built: 14th century
Remaining remnants: Clay walls and moats
Title:

Brief History

Tendo castle（天童城） is located over Maizuru-yama mountain, one of about 150 meter height from hillside at the center of current Tendo city. Body of the mountain is a “C” shaped circular facing its gap toward north, surrounding Atago-numa lake. It is an independent hill separated from backside mountains, and even though a bit too large its structure and moderate height is suitable for the castle.

Tendo area is at the middle-east part of 30 kilometer long Yamagata basin. In addition to its agricultural production at the broadest part of the basin, this area is also a place of communication where north and southward main road of the basin that is current Route 13 crosses east and westward road toward Shonai area at west and Sendai area at east currently used as Route 112 and Route 48.

Based on above conditions, currently Tendo city is one of three large cities in the basin, along with Yamagata city in the south part and Murayama city in the north part. Except for Yamagata city later developed as the center of the domain and prefecture, current major cities and towns in the basin were also the territories of major local lords in medieval era.

Origin of Tendo castle

Tendo castle was used by local lord Tendo clan. Tendo clan was originally a descendant of Minamoto clan and branch family of Nitta clan, which is known for Yoshisada Nitta (1301-1338), a commander of the South Court army in 14th century. At first Tendo clan was a part of Satomi clan, which became a warlord at Boso peninsula of current Chiba prefecture.

Around the end of Kamakura era, under the political conflict and tension, a part of Satomi clan moved to their manor at Tendo area and named as Tendo clan. At first Tendo clan lived at Nariu area in the northwest part of Tendo city and built Nariu castle, a small flat castle.

After the fall of Kamakura Shogunate in 1333, a long conflict occurred between Muromachi Shogunate established by Takauji Ashikaga (1305-1358) and the South Court lead by Emperor Godaigo (1288-1339). The South Court sent their strong general Akiie Kitabatake (1318-1338) to seize Tohoku region.

Kitabatake clan vs Shiba clan

To secure Yamagata basin which is at the side of Sendai basin, where Tagajo castle (Miyagi prefecture) which was the main base exists, it is said that Akinobu Kitabatake sent his son Tendomaru Kitabatake (?-?) to Yamagata basin. Tendomaru entered Yamagata basin built Tendo castle at the place of Tendo, ahead of Sekiyama-Toge pass which crosses Ou mountains.

In response to this, Muromachi Shogunate sent their major relative Iekane Shiba (1308-1356) to Tohoku region as "Oshu Tandai" (general commander of Tohoku region). As Akiie Kitabatake who had brilliant military talent died in the battle of Ishizu after long expedition to Kyoto city, the South Court significantly declined then Shiba clan could roughly seize Tohoku region by the middle of 14th century.

Next Iekane sent his son Kaneyori Shiba (1316-1379) to Yamagata basin. As local lords still resisted under the name of South Court, Kaneyori broke such lords and forced them to follow to the Shogunate. During this battle Tendomaru Kitabatake finally left Tendo castle, and is said to move to Tsugaru peninsula of current Aomori prefecture and built Ajigasawa area.

Mogami clan and Tendo clan

Iekane Shiba built Yamagata castle (Yamagata prefecture) and named as Mogami clan, then sent his son as a successor of Tendo clan which was the largest local lord of the area succeeding the territory of Kitabatake Tendomaru. Now Tendo clan became branch family of Mogami clan but still held their own tradition, thus this became the conflict of Mogami clan and Tendo clan later.

Contrary to Mogami clan which kept the south part of Yamagata basin, Tendo clan placed their branch families at Tone area, Takasu area or Kaminoyama area surrounding the territory of Mogami clan. At this time Tendo clan became equivalent to Mogami clan which was the governor of Dewa province (Yamagata and Akita prefecture), and Tendo castle was expanded along the development of the clan.

Structure of Tendo castle

Tendo castle spread over “C” shaped Maizuru mountain and consist of central part, east part and west part. Central part includes central area of about 100 meter long and 30 meter wide, which has basement of watchtower at east edge. From the main entrance at the border of central part and western part, about 10 small terraces were built at the slope.

Eastern part starts ahead of saddle point just below of central area, which might work as a large dry moat to separate central part and eastern part. Ahead of large area of about 150 meter long and 30 meter wide, many terraces are built along with the slope from hilltop to hillside.

Western part lost structures of hilltop part because of the construction of the part, but corridor terraces surrounding hilltop part well remain especially at north slope and west slope. At the south of western part, south part is built utilizing small park. Total size of Tendo castle is about 600 meter long square, and its size and security exceeded Yamagata castle, the main base of Mogami clan.

Alliance of eight local lords

In the beginning of 16th century, Mogami clan lost its power by internal conflicts and was defeated by Date clan, which was originally the warlord of Date area ahead of Ou mountains but captured Yonezawa basin in the south of Yamagata basin, at the battle of Hasedo castle (Yamagata prefecture) and was controlled by Date clan.

Major local lords other than Mogami clan, including Tendo clan, Nobesawa clan of Nobesawa castle (Yamagata prefecture), Hosokawa clan of Oguni castle (Yamagata prefecture), Kaminoyama clan of Kamiyoyama castle (Yamagata prefecture) or Tone clan of Tone castle (Yamagata prefecture) formed an alliance called as “Mogami Hachidate” (eight castles of Mogami area) to keep independence from Date clan.

Later Yoshimori Mogami (1521-1590) left Date clan utilizing their internal conflict and recovered independence, but next Yoshimori and his son Yoshiaki Mogami (1546-1614) fought for the leader. As Yoshiaki tried to strengthen the control to local lords, Tendo clan and other local lords supported Yoshimori, but in 1574 finally Yoshiaki broke Yoshimori and supporting Date army then stabilized his situation.

One-by-one attack to alliance

In 1577, Yoshiaki attacked Tendo clan, but as Mogami territory was surrounded by circular alliance Yoshiaki could not focus his army to Tendo clan. There was no result and once both party agreed under the condition of marrying Yoshiaki and the daughter of Tendo clan. But Yoshiaki made plot to divide the alliance and make one-by-one attack.

In 1580, Yoshiaki let Satomi clan, an important retainer of Kaminoyama clan, assassinate their master and turn to Mogami clan. Next Yoshiaki marched to Mogami providence and broke Oguni clan and next turned Hidetsuna Sakenobe (1563-1616) to Mogami clan, then built reverse encirclement against Tendo clan.

In the meantime, the daughter of Tendo clan who became the concubine of Yoshiaki died in ill, then Yoshiaki and Tendo clan broke in 1582. Two years later Yoshiaki attacked Tendo clan again but was stroke back by the activation of Mitsunobu Nobesawa (1544-1591), the lord of Nobesawa castle and relative of Tendo clan.

Afterward of Tendo clan and Tendo castle

Evaluation the braveness of Mitsunobu Nobesawa and economic income of Nobesawa silver mine in the territory, Yoshiaki let Mitsunobu Nobesawa marry with his daughter and turned him to the retainer. Alliance of local lords collapsed by the plot of Yoshiaki, and finally isolated Tendo clan left Tendo castle and ran into Date clan in 1584.

At this time Nobesawa clan made a promise with Yoshiaki not to kill Tendo clan, Yoshiaki did not chase Tendo clan and let them go. Considering its location and size Tendo castle might be suitable for new main base of Mogami clan, but Yoshiaki did not use Tendo castle and abolished. Closeness to Date clan which was the fatal rival of Mogami clan might be disliked.

Now all building was lost and western part was destructed by the construction of the park, structure of the castle having layers of small terraces still remains over the mountain. Today hilltop area is covered by trees and has no good scenery, but formerly it had great scenery of whole part of Yamagata basin. Circular shape of the castle separated into three parts resembles the alliance of local lords that encircled Mogami clan but was divided and collapsed by individual attack.

Access

30 minutes walk from JR East Yamagata-Shinkansen line Tendo station. 20 minutes drive from Tohoku Chuo Jidoshado Expressway Tendo interchange to hillside parking of Tendo-Koen park.