Oyama Castle

Japanese: 小山城 - おやまじょう

This castle was located in Oyama City, Tochigi Prefecture. Along with the ruins of Nakakuki Castle and Washi Castle, it is a designated national historic site. Its origins are said to date back to around 1150 (Kyuan 6), when Oyama Masamitsu, a member of the Ota clan, whose main territory was in Musashi Province since the Heian period, moved to Oyama in Shimotsuke Province and built a residence there. Masamitsu took the name Oyama from then on. The Oyama clan went on to be appointed as the guardian of Shimotsuke Province during the Kamakura period. At the time, the Oyama clan's castle was Washi Castle (in the same city), and Oyama Castle was merely a subsidiary castle, but after Oyama Yasutomo, the head of the family during the Nanboku-cho period, moved his castle to Oyama Castle, it became the main castle of the Oyama clan. It was the base of the Oyama Yoshimasa Rebellion, which took place from 1380 (Kōryaku 2) to 1383 (Eitoku 2). The Oyama clan was pursued and extinguished by the Muromachi shogunate during this rebellion, but was later revived by adopting a son from the Yuki family, a related clan. In 1574 (Tensho 2), Oyama Castle fell to an attack by the Hojo army, and the lord of the castle, Koyama Hidetsuna, fled to Satake Yoshishige in Hitachi Province. Oyama Castle became the castle of the Hojo clan, and Hojo Ujiyasu expanded it as a base for the invasion of northern Kanto. Later, Koyama Hidetsuna returned to Oyama Castle with the help of Takigawa Kazumasu, a senior vassal of Oda Nobunaga who entered Umabashi Castle (Maebashi City, Gunma Prefecture) as the Kanto Kanrei, and became a subordinate of the Hojo clan. However, since it was subordinate to the Hojo clan, Oyama Castle fell to an attack by Yuki Harutomo in 1590 (Tensho 18) during the Siege of Odawara, and the Koyama clan was extinguished. Koyama Castle is also known as the castle where Tokugawa Ieyasu, who was heading to conquer the Uesugi clan of Aizu in 1600 (Keicho 5), held a council after learning of Ishida Mitsunari's uprising. In 1616 (Genwa 2), Honda Masazumi entered Oyama Castle with a fief of 30,000 koku, but in 1619 (Genwa 5), he was transferred to Utsunomiya Castle, and Oyama Castle was abandoned. Currently, the castle ruins are Shiroyama Park, and earthworks, moats, and horse-sheds remain. About 8 minutes walk from Oyama Station on the JR Tohoku Main Line and Utsunomiya Line. ◇It is also called Gion Castle (Gion Castle).

Source: Kodansha Encyclopedia of Japanese Castles Information

Japanese:

栃木県小山市にあった城。中久喜城跡、鷲城跡とともに国指定史跡となっている。平安時代以来、武蔵国に本領を有した太田氏一族の小山政光が1150年（久安6）ごろに、下野国小山に移住して築いた居館がその起源とされる。政光はこれ以降小山氏を名乗った。小山氏は鎌倉時代には下野国守護に任じられるまでになった。当時、小山氏が居城としていたのは鷲城（同市）で、小山城はその支城に過ぎなかったが、南北朝時代の当主の小山泰朝が居城を小山城に移して以来、小山氏の本城となった。1380年（康暦2）から1383年（永徳2）にかけて起こった小山義政の乱では、その拠点となった。この乱で小山氏は室町幕府の追討を受けて断絶したが、のちに同族の結城家から養子を迎えて再興した。1574年（天正2）、小山城は北条軍の攻撃により落城して、城主の小山秀綱は常陸国の佐竹義重のもとに逃れた。小山城は北条氏の城となり、北関東攻略の拠点として北条氏照による城の拡張が行われた。その後、小山秀綱は関東管領として厩橋城（群馬県前橋市）に入った織田信長重臣の滝川一益のはからいで小山城に戻り、北条氏配下となった。しかし、北条氏の配下であったことから、小山城は1590年（天正18）の小田原の役の際に結城晴朝の攻撃を受けて落城し、小山氏は断絶した。小山城は1600年（慶長5）、会津の上杉氏征伐に向かった徳川家康が石田三成の挙兵を知り、評定を行った城としても知られる。1616年（元和2）、本多正純が3万石で小山城に入城したが、正純は1619年（元和5）に宇都宮城に転封となったことから、小山城は廃城となった。現在、城跡は城山公園となっており、土塁・堀切・馬出しなどが残っている。JR東北本線・宇都宮線小山駅から徒歩約8分。◇祇園城（祗園城）とも呼ばれる。

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