A Thorough Explanation of the History and Remains of Kizu Castle | The Complete Picture of Medieval Mountain Castles in Yamashiro Province
What is Kizu Castle?
Kizu Castle is a medieval mountain castle built on Shiroyama (elevation 107m) on the left bank of the Kizu River in Kizugawa City, Kyoto Prefecture. As an important military base in Yamashiro Province (present-day southern Kyoto Prefecture), it played a crucial role during the turbulent Sengoku period, particularly during the Ōnin War.
While the area around the current Kizu Station has undergone residential development, and the area around the castle ruins has become a newly developed residential area called “Shiroyamadai,” the remains of the medieval mountain castle are still well-preserved on the summit of Shiroyama and are protected as a cultural property of Kyoto Prefecture.
Location and Geographical Importance of Kizu Castle
Kizu as a Transportation Hub
Kizu, where Kizu Castle was built, has long been known as a transportation hub. This location was a crucial point where water transport on the Kizu River intersected with land transport, situated on an important route connecting Yamato Province (Nara) and Yamashiro Province (Kyoto). Even today, the presence of Kizu Station, where three JR lines converge (Kansai Main Line, Nara Line, and Gakken Toshi Line), demonstrates the geographical importance of this area.
Topographical Characteristics of Shiroyama
Shiroyama, where Kizu Castle was built, is an isolated hill with an elevation of 107m and a relative height of approximately 60m. Overlooking the plains on the left bank of the Kizu River, its terrain was well-suited for monitoring and defense of the surrounding area. The mountaintop was relatively flat, making it suitable for constructing baileys.
History of Kizu Castle
Construction and the Kizu Clan
The exact construction date of Kizu Castle is unknown, but it is believed to have been built by the local lord, the Kizu clan. The Kizu clan were powerful local lords who controlled the Kizu Manor and held influence in this region from the Muromachi period to the Sengoku period.
The oldest record is an account from 1457 (Kōshō 3) stating that the Kizu clan, attacked by Hatakeyama Yoshinari, burned down Kizu Castle. This occurred during the Hatakeyama clan’s succession dispute preceding the Ōnin War, indicating that Kizu Castle was already functioning as a military base at this time.
The Ōnin War and Kizu Castle
During the Ōnin and Bunmei eras (1467-1487), Kizu Castle became a crucial battlefield in the Ōnin War. The Kizu clan sided with the Eastern Army (Hosokawa Katsumoto’s faction) and was attacked by the Western Army (Yamana Sōzen’s faction).
Fierce battles raged over Kizu Manor. Because this region was a strategic point connecting Kyoto and Yamato, it held high strategic value for both sides, leading to repeated struggles for control. The battles for Kizu Castle during the Ōnin War were a microcosm of the power struggle between the Eastern and Western armies in southern Yamashiro Province.
After the Sengoku Period
It is believed that Kizu Castle continued to exist as a base for local lords even after the Ōnin War, but detailed records do not remain. As the Sengoku period progressed, larger castles were built in the surrounding area, and it is presumed that the military importance of Kizu Castle relatively declined.
Kizu Castle’s Layout and Remains
Basic Structure
Kizu Castle is a single-enclosure mountain castle. The main enclosure is located on the hilltop, and it is defended by moats and lateral trenches. While it is a typical layout for a medieval mountain castle, the remains are well-preserved, making it a valuable resource for understanding the castle-building techniques of the time.
Main Enclosure (Enclosure)
The main enclosure, located on the top of the castle mountain, is surrounded by earthen ramparts. The size of the enclosure is not particularly large, but it is a standard size for a castle of a local lord like the Kizu clan. The flat surface of the enclosure and traces of the earthen ramparts can still be seen today.
Moat
A moat surrounds the main enclosure. Moats are defensive structures that prevent enemy intrusion by cutting off the ridge, and are an important element of medieval mountain castles. The moats at Kizu Castle remain clearly visible today, allowing us to understand the defensive system of the time.
Horizontal Moat and Flanking Fire
Of particular note is the horizontal moat on the south side. This moat has a bend, and it is believed to have functioned as flanking fire. Flanking fire is a defensive technique that allows for attacks from the flank by creating bends in moats or enclosures.
The existence of this flanking fire indicates that Kizu Castle was not merely a simple mountain castle, but was constructed using a certain level of advanced castle-building technology. It is also possible that its defensive functions were strengthened through experience in actual combat, such as the Ōnin War.
Current Status of the Remains
Currently, the Kizu Castle site is maintained as Kizu Castle Ruins Park, and a parking lot is available. It is located about 10-20 minutes on foot from JR Kizu Station, making it relatively easy to access. While the development of the new residential area of Shiroyamadai is progressing, the castle ruins themselves are protected, and it is possible to actually visit the remains such as moats, lateral moats, and earthworks.
Historical Significance of Kizu Castle
Characteristics as a Local Lord’s Castle
Kizu Castle was not a large-scale fortress like the residences of Sengoku-period daimyo, but rather the base of the Kizu clan, a local lord. Such small to medium-sized mountain castles are important historical sources for understanding the realities of regional governance in the medieval period. They provide clues to how local lords like the Kizu clan governed their territories and how they survived periods of war.
Local Battlefronts in the Ōnin War
While the Ōnin War is often associated with battles within Kyoto, fierce fighting also took place in surrounding areas such as Yamashiro Province and Yamato Province. The battle at Kizu Castle demonstrates that the Ōnin War was not merely urban warfare in Kyoto, but a large-scale civil war involving a wide area.
Control of Transportation Routes
Because Kizu was a crossroads of water transport on the Kizu River and land routes, Kizu Castle functioned as a base for controlling these transportation routes. In the Middle Ages, controlling a key transportation hub was extremely important both economically and militarily. The history of Kizu Castle offers valuable insights into the nature of transportation, logistics, and regional governance in the Middle Ages.
Cultural Value of Kizu Castle
The Kizu Castle ruins have been designated a cultural property by the Kyoto Prefectural Board of Education, recognizing their historical and academic value. Examples of well-preserved medieval mountain castle remains are rare, making the Kizu Castle ruins a valuable historical heritage site.
With its single enclosure on the hilltop, surrounding earthworks, moats, lateral moats, and curved sections with flanking fire capabilities, it possesses typical elements of a medieval mountain castle, making it an excellent learning resource for studying castle construction techniques and defensive systems.
Access to and Visiting Kizu Castle
Access Methods
By Train:
- Approximately 10-20 minutes on foot from JR Kizu Station (Kansai Main Line, Nara Line, Gakken Toshi Line)
- Head southeast from the station towards Shiroyama (Castle Hill)
By Car:
- There is a parking lot at Kizu Castle Ruins Park
- The surrounding area is a residential area, so please follow the signs.
Points to Note During Your Visit
- Main Enclosure Earthworks: Check the flat surface at the top and the surrounding earthworks.
- Moat: Observe an example of a defensive structure that cuts off a ridge.
- Horizontal Moat and Flanking Fire Positions: Pay attention to the horizontal moat on the south side. The curved section functioned as a flanking fire position.
- View: From the castle hill, you can overlook the plains of the Kizu River basin, allowing you to appreciate the castle’s excellent location.
Points to Note When Visiting
- As it is a mountain castle, we recommend wearing comfortable shoes and clothing.
- Insect repellent is necessary during the summer months.
- Please walk on the designated viewing paths to avoid damaging the remains.
- The surrounding area is a residential neighborhood, so please be considerate of the neighbors regarding noise and other disturbances.
Other Historical Spots in Kizugawa City
When visiting Kizu Castle, we recommend also visiting other historical spots in Kizugawa City.
- Jōruri-ji Temple: An ancient temple known for its National Treasure main hall and nine Amida Buddha statues.
- Iwafune-ji Temple: An ancient temple with a beautiful three-story pagoda.
- Kuni Palace Site: The site where the capital was temporarily located during the Nara period.
- Kaijūzan-ji Temple: A mountain temple with a National Treasure five-story pagoda.
By visiting these spots, you can gain a deeper understanding of the rich history and culture of Kizugawa City.
Differences from the same-named Kizu Castle (Tokushima Prefecture)
There are actually several castles named “Kizu Castle.” The most well-known are Kizu Castle in Kizugawa City, Kyoto Prefecture (Yamashiro Province), which is introduced in this article, and Kizu Castle in Naruto City, Tokushima Prefecture.
Kizu Castle in Tokushima Prefecture
Kizu Castle, located in Kizu, Muya-cho, Naruto City, Tokushima Prefecture, was built by Shinohara Jiton, a samurai of the Miyoshi clan. The castle was defended by the Shinohara clan from the Eiroku era (1558-1570). During Chosokabe Motochika’s invasion of Awa Province in 1582, the Shinohara clan did not participate in the Battle of Nakatomigawa or the siege of Katsuzui Castle, ultimately surrendering the castle and fleeing to Awaji Island.
Kizu Castle in Tokushima Prefecture is a designated historical site of Naruto City and is also an important historical heritage site.
To Avoid Confusion
Since there are two castles with the same name, it is important to be careful which Kizu Castle is being referred to when reading documents or visiting castle ruins. Generally, the province name is added to distinguish them, such as “Kizu Castle (Yamashiro Province)” or “Kizu Castle (Awa Province).”
Current Status and Challenges of Kizu Castle Research
Historical materials concerning Kizu Castle are limited, and many points remain unknown regarding its construction date and detailed history. Future research topics include the following:
The Need for Archaeological Investigation
If a full-scale excavation is conducted, it may be possible to obtain more detailed information about the castle’s construction date, period of use, and function from the unearthed artifacts. In particular, the discovery of pottery fragments and weapon/armor fragments would be helpful in determining the castle’s age and elucidating the living conditions of the time.
Excavation of Historical Documents
There is a possibility that descriptions of Kizu Castle may be found in historical documents that have not yet been sufficiently investigated, such as the diaries of the Kizu clan, surrounding temples and shrines, and court nobles. A steady accumulation of historical document research will lead to a clearer understanding of Kizu Castle’s history.
Relationship with Surrounding Castles
Kizu Castle may not have existed in isolation, but rather formed a network with surrounding castles and forts. A comprehensive study of the castle complex in southern Yamashiro Province will provide a clearer understanding of the regional defense system and power dynamics.
Summary
Kizu Castle is a medieval mountain castle built on Shiroyama in Kizugawa City, Kyoto Prefecture, by the local lord, the Kizu clan. During the Ōnin War, Kizu Castle served the Eastern Army and was the site of fierce battles against the Western Army.
The castle, situated on a 107-meter-high mountaintop, features a single enclosure and is defended by moats and lateral trenches, a typical structure for a medieval mountain castle. The southern lateral trench, in particular, had a bend designed to function as a flanking fire position, demonstrating practical defensive features.
The remains are still well-preserved today and the castle is easily accessible on foot from JR Kizu Station. As a valuable historical site where one can experience the structure of a medieval mountain castle firsthand, and as a place to understand the major historical events of the Ōnin War at a local level, Kizu Castle ruins are well worth a visit for history enthusiasts.
When visiting Kizugawa City, be sure to visit Kizu Castle ruins and feel the spirit of the Middle Ages. In today’s world of ongoing residential development, the quiet presence of the castle mountain, continuing to tell its history, teaches us the weight of history that transcends time.
