is a "yamashiro"-style (

castle A castle is a type of fortification, fortified structure built during the Middle Ages predominantly by the nobility or royalty and by Military order (monastic society), military orders. Scholars usually consider a ''castle'' to be the private ...

located on Mount Iwabitsu in Higashiagatsuma,

Gunma Prefecture is a landlocked Prefectures of Japan, prefecture of Japan located in the Kantō region of Honshu. Gunma Prefecture has a population of 1,937,626 (1 October 2019) and has a geographic area of . Gunma Prefecture borders Niigata Prefecture and Fuk ...

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

. The ruins have been protected by the central government as a National Historic Site since 2019.

Overview

Iwabitsu Castle is located in northwestern Gunma Prefecture in the middle of a long valley created by the

Agatsuma River The is a major river in the northern Kantō region of Japan. It is in length and has a basin area of . Located entirely within Gunma Prefecture, it is one of the prefecture's major rivers. It is also a major tributary of the Tone River. The river ...

(a tributary of the

Tone River The is a river in the Kantō region of Japan. It is in length (the second longest in Japan after the Shinano River) and has a drainage area of (the largest in Japan). It is nicknamed Bandō Tarō (); ''Bandō'' is an obsolete alias of the ...

). This valley was the route of the Shinshu Kaidō, a road which led from Takasaki to

Shinano Province or is an old province of Japan that is now Nagano Prefecture. Shinano bordered Echigo, Etchū, Hida, Kai, Kōzuke, Mikawa, Mino, Musashi, Suruga, and Tōtōmi Provinces. The ancient capital was located near modern-day Matsumoto, whi ...

via the Torii Pass, and the castle thus controlled a strategic point on this highway.

History

The origins of the Iwabitsu Castle are uncertain, but it is believed to have been built by the local Agatsuma clan sometime in the 13th century. During the

Muromachi period The , also known as the , is a division of Japanese history running from approximately 1336 to 1573. The period marks the governance of the Muromachi or Ashikaga shogunate ( or ), which was officially established in 1338 by the first Muromachi ...

, it was held by the Saitō clan, another local warlord. However, in the early

Sengoku period The was the period in History of Japan, Japanese history in which civil wars and social upheavals took place almost continuously in the 15th and 16th centuries. The Kyōtoku incident (1454), Ōnin War (1467), or (1493) are generally chosen as th ...

, it was captured by

Sanada Yukitaka was a Japanese samurai warrior of the Sengoku period. He is known as one of the "Twenty-Four Generals of Takeda Shingen". He was the father of Sanada Nobutsuna and Sanada Masayuki and grandfather of the legendary samurai warrior Sanada Yukim ...

, who had expanded from Shinano Province into northern

Kōzuke Province was a Provinces of Japan, province of Japan in the area of Japan that is today Gunma Prefecture. Kōzuke bordered Echigo Province, Echigo, Shinano Province, Shinano, Musashi Province, Musashi and Shimotsuke Province, Shimotsuke Provinces. Its abb ...

with the backing of his overlord,

Takeda Shingen was daimyō, daimyo of Kai Province during the Sengoku period of Japan. Known as "the Tiger of Kai", he was one of the most powerful daimyo of the late Sengoku period, and credited with exceptional military prestige. Shingen was based in a p ...

. The Saitō clan had turned to

Uesugi Kenshin , later known as , was a Japanese ''daimyō'' (magnate). He was born in Nagao clan, and after adoption into the Uesugi clan, ruled Echigo Province in the Sengoku period of Japan. He was one of the most powerful ''daimyō'' of the Sengoku period ...

Echigo Province was an old provinces of Japan, old province in north-central Japan, on the shores of the Sea of Japan. It bordered on Uzen Province, Uzen, Iwashiro Province, Iwashiro, Kōzuke Province, Kōzuke, Shinano Province, Shinano, and Etchū Province, ...

for assistance, but due to the distance from Echigo and the stratagems employed by the Sanada, the castle fell in 1563.

Sanada Masayuki was a Japanese Sengoku period lord and ''daimyō''. He was the head of Sanada clan, a regional house of Shinano Province, which became a vassal of the Takeda clan of Kai Province. Along with his father and brothers, Masayuki served the Taked ...

used Iwabitsu Castle as his base to continue his expansion into northern Kōzuke, capturing Numata Castle in 1579. He also rebuilt the Iwabitsu ''

jōkamachi The were centres of the domains of the feudal lords in medieval Japan. The ''jōkamachi'' represented the new, concentrated military power of the daimyo in which the formerly decentralized defence resources were concentrated around a single, cent ...

'' into a fortified ''

shukuba were Stage station, staging post stations during the Edo period in Japan, generally located on one of the Edo Five Routes or one of its sub-routes. They were also called ''shuku-eki'' (宿駅). These stage stations, or "" developed around them, ...

'' by surrounding the entire town with a series of forts and gates, similar to the layout which he later employed when designing the new stronghold for the

Takeda clan The was a Japanese samurai clan active from the late Heian period until the late 16th century. The clan was historically based in Kai Province in present-day Yamanashi Prefecture. The clan reached its greatest influence under the rule of Taked ...

Shinpu Castle was a Sengoku period ''hirayama''-style Japanese castle located in what is now part of the city of Nirasaki, Yamanashi prefecture. It was the primary fortress of the warlord Takeda Katsuyori. The ruins have been protected as a National Historic ...

as few years later. After the fall of the Takeda clan in 1582, Sanada Masayuki had planned to provide refuge for

Takeda Katsuyori was a Japanese ''daimyō'' (military lord) of the Sengoku period, who was famed as the head of the Takeda clan and the successor to the legendary warlord Takeda Shingen. He was son-in-law of Hojo Ujiyasu, ''daimyō'' of Hojo clan. Early life H ...

at Iwabitsu Castle, but Katsuyori was unable to reach it due to treachery by some of his remaining retainers and committed ''

seppuku , also known as , is a form of Japanese ritualistic suicide by disembowelment. It was originally reserved for samurai in their code of honor, but was also practiced by other Japanese people during the Shōwa era (particularly officers near ...

''. The famed

samurai The samurai () were members of the warrior class in Japan. They were originally provincial warriors who came from wealthy landowning families who could afford to train their men to be mounted archers. In the 8th century AD, the imperial court d ...

Karasawa Genba was an officer at the castle. Following the establishment of a stable regime under

Toyotomi Hideyoshi , otherwise known as and , was a Japanese samurai and ''daimyō'' (feudal lord) of the late Sengoku period, Sengoku and Azuchi-Momoyama periods and regarded as the second "Great Unifier" of Japan.Richard Holmes, The World Atlas of Warfare: ...

, Iwabitsu and Numata were awarded to

Sanada Nobuyuki was a Japanese samurai of the Sengoku period. He was the son of ''daimyō'' Sanada Masayuki and the older brother of Sanada Yukimura. Early life He was the first son of Sanada Masayuki and his wife, Kansho-in. His younger brother was Sanada Yu ...

, while his father Masayuki retained

Ueda Castle is a Japanese castle located in Ueda, northern Nagano Prefecture, Japan. At the end of the Edo period, Ueda Castle was home to a cadet branch of the Matsudaira clan, ''daimyō'' of Ueda Domain, but the castle is better known for its association w ...

. Following the death of Toyotomi Hideyoshi, Sanada Masayuki remained loyal to

Toyotomi Hideyori was the son and designated successor of Toyotomi Hideyoshi, the general who united all of Japan toward the end of the Sengoku period. His mother, Yodo-dono, was the niece of Oda Nobunaga. Early life Born in 1593, he was Hideyoshi's sec ...

and his regent

Ishida Mitsunari was a Japanese samurai and military commander of the late Sengoku period of Japan. He is probably best remembered as the commander of the Western army in the Battle of Sekigahara following the Azuchi–Momoyama period of the 16th century. He ...

, whereas Sanada Nobuyuki, sided with

Tokugawa Ieyasu Tokugawa Ieyasu (born Matsudaira Takechiyo; 31 January 1543 – 1 June 1616) was the founder and first ''shōgun'' of the Tokugawa shogunate of Japan, which ruled from 1603 until the Meiji Restoration in 1868. He was the third of the three "Gr ...

. With the victory by Tokugawa forces at the

Battle of Sekigahara The Battle of Sekigahara (Shinjitai: ; Kyūjitai: , Hepburn romanization: ''Sekigahara no Tatakai'') was an important battle in Japan which occurred on October 21, 1600 (Keichō 5, 15th day of the 9th month) in what is now Gifu Prefecture, ...

in 1600, Sanada Nobuyuki was confirmed in his holdings in northern Kōzuke, but due to the

Tokugawa shogunate The Tokugawa shogunate, also known as the was the military government of Japan during the Edo period from 1603 to 1868. The Tokugawa shogunate was established by Tokugawa Ieyasu after victory at the Battle of Sekigahara, ending the civil wars ...

’s rule of “one domain – one castle” in 1615, Iwabitsu Castle was abolished. The ''jōkamachi'' survived as post station on the highway, but was relocated closer to the Agatsuma River. At present, nothing survives of the original castle. The entrance to the site is approximately 30 minutes on foot from Gunma-Haramachi Station on the

JR East The is a major passenger railway company in Japan and the largest of the seven Japan Railways Group companies. The company name is officially abbreviated as JR-EAST or JR East in English, and as in Japanese. The company's headquarters are in ...

Agatsuma Line The is a local rail line in Gunma, Japan, and is part of the East Japan Railway Company (JR East) network. Approximately following the Agatsuma River, it is 55.6 km between and stations. Operations Although the official start of the line ...

, followed by another 30 minute hike up the side of the mountain to reach the location of the

inner bailey The inner bailey or inner ward of a castle is the strongly fortified enclosure at the heart of a medieval castle.Friar, Stephen (2003). ''The Sutton Companion to Castles'', Sutton Publishing, Stroud, 2003, p. 22. It is protected by the outer ...

. Iwabitsu Castle was listed as one of the

Continued Top 100 Japanese Castles The is a list of 100 Japanese castle, castles, intended as a sequel of 100 Fine Castles of Japan. The castles were chosen for their significance in culture, history, and in their regions by the in 2017. Hokkaidō region Tōhoku region Kant ...

in 2017.

Literature

* * * *

References

{{Continued Top 100 Japanese Castles Castles in Gunma Prefecture Ruined castles in Japan Sanada clan Higashiagatsuma, Gunma

Overview

History

See also

Literature

References