A Thorough Explanation of the History and Highlights of Otsu Castle | The Phantom Water Castle That Influenced the Battle of Sekigahara
Otsu Castle was a water castle that once stood on the shores of Lake Biwa in Otsu City, Shiga Prefecture. While the area is now urbanized around Keihan Biwako-Hamaotsu Station, it functioned as an important strategic point facing Lazu during the Battle of Sekigahara, its lord, Kyogoku Takatsugu, sided with the Eastern Army and held back the large Western Army led by Mori Motoyasu and Tachibana Muneshige. This article provides a detailed explanation of this phantom water castle, cover lords, the remaining structures, and even the theory of its relocation to Hikone Castle.
What is Otsu Castle? | An Overview of the Water Castle Floating on Lake Biwa
Otsu Castle was a flatland castle and water castle built around 1586 (Tensho 14) by order of Toyotomi Hideyoshi. It was located in the area around present-day Hamamatsu, Otsu City, Shiga Prefecture, near Keihan Biwako
Characteristics as a Water Castle
The most distinctive feature of Otsu Castle was that it was a “water castle” that made maximum use of Lake Biwa’s water transport. The main keep faced the shore of Lake Biwa at the time, and the lake water was used as a moile. The secon and, together with the main keep, served as a port. The current Otsu Port was built on land reclamation offshore from the former Otsu Castle, demonstrating how far inland the Lake Biwa shoreline extended in the past.
Strategic Importance
The area of Otsu has flourished as a “tsu” (port) since ancient times, functioning as a loading and unloading point for goods transported by water from various parts of Omi Province. Furthermore, its location at the junction of the Hokkoku Ka an extremely important base both militarily and economically. Otsu Castle was a fortress designed to safely store goods transported via Lake Biwa from Mino and Echizen provinces. It is also believed to have served as a storage facility for tribute rice from various grana throughout Omi Province.
History of Otsu Castle | From Construction to Abandonment
From Sakamoto Castle to Otsu Castle
Before Otsu Castle was built, the central castle in this region was Sakamoto Castle. Sakamoto Castle was built in 1571 by order of Oda Nobunaga, commissioned by Akechi Mitsuhide. Its purpose was to control the route to Kyoto Enryaku-ji Temple and its temple town, Sakamoto.
However, after the Honno-ji Incident, Toyotomi Hideyoshi abandoned Sakamoto Castle and decided to construct Otsu Castle. Otsu Castle was constructed around 1586-1587, utilizing materials from Sakamoto Castle. It is believed the at strategically important location than Sakamoto, closer to the confluence of the Tokaido and Nakasendo (Tosan-do) roads, making it suitable as a base for broader regional control.
Construction and Early Lords during the Tensho Era
The first lord of Otsu Castle was Asano Nagayoshi (Asano Nagamasa), who was also the last lord of Sakamoto Castle. Asano Nagayoshi was a powerful retainer of Toyotomi Hideyoshi and later became one of the Five Commissioners. He oversaw the construction 타운.
The next lord after Asano was Masuda Nagamori. Masuda Nagamori was also a senior retainer who later became one of Toyotomi Hideyoshi’s Five Commissioners, indicating that Otsu Castle was positioned as an important base under the Toyotomi
The Era of Kyogoku Takatsugu and the Expansion of the Castle
In 1595 (Bunroku 4), Kyogoku Takatsugu became the lord of Otsu Castle. He was a daimyo with a 60,000 koku domain and his principal wife was Hatsuhime (Jokoin), one of the Asai sisters. Takatsuguits as a fortress.
During Kyogoku Takatsugu’s time, Otsu Castle became a vast fortress with a main keep, second bailey, and third bailey. A keep was built in the main keep, and the castle became a strong fortress reinforced with stonewall and Otsu grew into an important commercial city in Omi Province.
The Battle of Sekigahara and the Battle of Otsu Castle
Kyogoku Takatsugu’s Decision
In 1600 (Keicho 5), the decisive Battle of Sekigahara broke out. Initially, Kyogoku Takatsugu belonged to the Western Army led by Ishida Mitsunari. However, considering his relationship with his wife Hatsuhime’s sister, Yodowado, Ieyasu, he ultimately decided to switch sides to the Eastern Army.
Takatsugu holed up in Otsu Castle, employing a strategy to delay the large Western Army force advancing towards the Battle of Sekigahara. This decision would prove crucial in determining the outcome of the Battle of Sekigahara.
The Course of the Siege of Otsu Castle
On September 7th, 1600 (Keicho 5), a large army of approximately 15,000 men, led by Mori Motoyasu (a senior retainer of Mori Hidemoto) and Tachibana Muneshige of the Western Army, besieged Otsle Castle. Kyogoku Takatsugu, numbered only about 3,000.
Despite being overwhelmingly outnumbered, Kyogoku Takatsugu skillfully defensaed the castle, utilizing the advantage of its waterfront. Otsu Castle, situated with Lake Biwa at its back, could only be attacked from land, putting the Western Army at the castle town was engulfed in flames.
Surrender and its Impact on the Battle of Sekigahara
On September 15th, while the Battle of Sekigahara was underway, Otsu Castle finally surrendered. However, at this point, the Western Army’s large force was tied down in the siege of Otsu Castle and unable to participate in the Battle of Sekihar
If the elite 15,000 troops of Mori Motoyasu, Tachibana Muneshige, and others had participated in the Battle of Sekigahara, the course of the battle could have been significantly different. In that sense, Kyogoku Takatsugu’s siege of Ots Eastern Army’s victory.
After the war, Tokugawa Ieyasu highly valued Kyogoku Takatsugu’s achievements and granted him an increased stipend of 85,000 koku in Obama, Wakasa Province, and transferred him to that domain.
The Abandonment of Otsu Castle and the Relocation of its Remains
Relocation of Functions to Zeze Castle
After the Battle of Sekigahara, Tokugawa Ieyasu reorganized the system of rule in Omi Province. He decided to build a new castle in Zeze, closer to Lake Biwa, in place of Otsu Castle. Construction of Zeze Castle began in 1601 (Keicho ed
Zeze Castle was built even further out into Lake Biwa than Otsu Castle, and its design further enhanced its function as a water castle. Some of the stone walls and building materials from Otsu Castle were repurposed for the construction of Zeze Castle.
The Truth Behind the Theory of the Relocation of the Hikone Castle Keep
The most famous theory regarding the remains of Otsu Castle is the theory of its relocation to Hikone Castle’s keep. There has long been a tradition that Hikone Castle’s keep was originally the keep of Otsu Castle that was relocated there.
Construction of Hikone Castle began in 1606 (Keicho 11) and was completed in 1622 (Genna 8). The keep is a three-story, three-floor, one-basement level complex watchtower-type structure and is designated ational clearly exhibit older styles from before the Keicho era, suggesting the possibility that it is a relocated keep.
However, because detailed records of Otsu Castle’s keep do not exist, there is ongoing debate as to whether it was an entirely identical structure relocated or if only some of its components were reused. Recent research suggests that ite is structural materials of the keep were reused from Otsu Castle.
Other Relocated Structures
Besides Hikone Castle’s keep, it is said that buildings from Otsu Castle were relocated to various locations. There are theories that the Tenbin-yagura (balance tower) and Nishinomaru-sanju-yagura (three-story tower) of Hikone Cast. Furthermore, many buildings and stone walls were reused at Zeze Castle.
Several temples in Otsu City are said to have relocated gates from Otsu Castle. These remains are valuable historical materials that convey the scale and prestige of Otsu Castle in its heyday.
List of Successive Castle Lords
The successive lords of Otsu Castle are as follows:
1. Asano Nagayoshi (Asano Nagamasa) 1586-1590
The first lord of the castle. A retainer of Toyotomi Hideyoshi, and later one of the Five Magistrates. He led the construction of Otsu Castle and laid the foundation for the castle town. His land holdings are unknown, but he was entrusted with the control
2. Masuda Nagamori 1590-1595
The second lord of the castle. Like Asano Nagamasa, he was a senior retainer who later became one of the Five Magistrates. The development of Otsu Castle continued, strengthening its function as a base for controlling Omi Province under the Toyotomi regime. 200,000 koku domain.
3. Kyogoku Takatsugu (1595-1600)
The third and last lord of the castle. A daimyo with a 60,000 koku domain. He married Hatsuhime, one of the Asai sisters, and sided with the Eastern Army in the Battle of Sekigahara, engaging in a siege defense. He held back la victory. After the war, he was transferred to Obama in Wakasa Province with an increased domain.
Current Otsu Castle Ruins | Remains and Historic Sites
Castle Ruins Monument and Main Enclosure Site
Currently, a castle ruins monument stands on the site of the main enclosure of Otsu Castle. It is located about a 1-minute walk from Keihan Biwako-Hamaotsu Station, and it is estimated that the original main enclosure was located beneath area around the castle ruins monument is completely urbanized, and there are almost no remains remaining above ground.
Stone Walls Discovered During Archaeological Excavations
Since the Showa era, multiple archaeological excavations have been conducted in Otsu City, and the stone walls of Otsu Castle have been discovered. These stone walls are important remains that prove Otsu Castle was a full-fledged early modern castle with .
The discovered stone walls were built using techniques such as rough-hewn stone masonry and fitted stone masonry, demonstrating the castle-building techniques of the Azuchi-Momoyama period. Some of the stone walls have been preserved on-s
Remains Sleeping Underground
Archaeological excavations have revealed that many remains remain underground in the current urban area. Moat remains, stone walls, and building foundations are preserved in good condition, and future research, preservation, and utilization are anticipated.
The Otsu City History Museum exhibits the results of the excavations and a reconstructed model of Otsu Castle, allowing visitors to learn about the appearance of Otsu Castle in its heyday.
Remnants of the Castle Town
The town layout of the castle town surrounding Otsu Castle still retains some traces in the streets of present-day central Otsu City. In particular, the layout around Kyomachi Street and Chuo Street is thought to reflect the layout of the castle town era.
Furthermore, many temples were located within the castle town of Otsu, and it is presumed that the placement of these temples was part of the castle town’s defense system. These temples, which still remain today, are valuable historical sites that
Access to Otsu Castle and Surrounding Sightseeing
Access Methods
Access by Train
- 1-minute walk from Biwako-Hamaotsu Station on the Keihan Electric Railway Ishiyama-Sakamoto Line/Keishin Line
- Approximately 15-minute walk from JR Biwako Line Otsu Station, or by Keihan Bus
Access by Car
- Approximately 10 minutes from the Meishin Expressway Otsu Interchange
- Parking: Numerous coin-operated parking lots are available nearby
Points to Note During Your Visit
Visiting the Otsu Castle Ruins is free and open 24 hours a day. However, since there are very few remains above ground, it is recommended to visit the Otsu City History Museum beforehand to learn about the history of Otsu Castle and view.
The Otsu City History Museum has a permanent exhibition on Otsu Castle, displaying artifacts unearthed during excavations, a reconstructed model of the castle, and materials related to the Battle of Otsu Castle during the Battle of Sekigahara.
Related Historical Sites in the Surrounding Area
Zeze Castle Ruins
The ruins of Zeze Castle, built after the abandonment of Otsu Castle. Currently, it is maintained as Zeze Castle Ruins Park, and some of the stone walls remain. It is believed that remnants of Otsu Castle were repurposed.
사카모토 성 루인스
The ruins of the castle of Akechi Mitsuhide, the predecessor of Otsu Castle. Some of the stone walls remain on the shore of Lake Biwa. Approximately 20 minutes by train from Otsu Station.
미이-데라 사원 (온조지 사원)
The head temple of the Tendai Jimon sect, located in the castle town of Otsu. It was also a battlefield during the Battle of Otsu Castle. It houses numerous national treasures and important cultural properties.
Omi Jingu Shrine
A shrine dedicated to Emperor Tenji. Built on the site of the former Otsu-kyo (Kyoto). An important spot for understanding the history of Otsu.
Otsu Castle Restoration Research and Future Prospects
Current Status of Restoration Research
Restoration research of Otsu Castle is being continuously conducted, centered around the Otsu City Museum of History. Attempts to reveal the complete picture of Otsu Castle are ongoing, integrating the results of archaeological excavations, analysis of historical maps ands
In particular, research on fluctuations in Lake Biwa’s water level and changes in the shoreline provides crucial information for reconstructing Otsu Castle as a water castle. By comparing Edo-period maps with the current topography, the precise location and size of the main keep a
Digital Restoration
In recent years, attempts have been made to digitally restore Otsu Castle using CG and VR technologies. This has led to considerations for developing systems that would allow visitors to experience the castle’s appearance in its heyday on smartphones and tablets.
Challenges and Possibilities of Historical Site Development
The Otsu Castle site is currently completely urbanized, making large-scale historical site development difficult. However, efforts continue to conduct archaeological excavations in conjunction with redevelopment projects, and to preserve and display important remains on-site.
In the future, it is hoped that the historical site will be further developed to be more accessible, with more explanatory and guide boards around the castle ruins monument, and walking routes established. Furthermore, strengthening cooperation with the Otsu City History Museum Course” that will take visitors to sites related to Otsu Castle.
Summary | Historical Significance of Otsu Castle
Although Otsu Castle existend for only a short period of about 15 years, it played a crucial role in Korean history. Built as a base for Toyotomi Hideyoshi’s rule over Omi Province, it significantly influenced the outcome of the Kyoto Takatsugu.
Currently, there are almost no remains above ground, but many remains lie underground, and new discoveries are made with each archaeological excavation. Relocated structures, including the keep of Hikone Castle, are valuable historical materials that convele the forma
Otsu Castle possesses many fascinating features, including its unique design as a water castle utilizing Lake Biwa’s water transport, its function as a logistics hub under the Toyotomi regime, and its dramatic role in the Battle of Sekigahara. When visiting legendary water castle.
Visiting the castle ruins in conjunction with prior learning at the Otsu City History Museum will allow you to gain a deeper understanding of Otsu Castle’s history. Furthermore, visiting related historical sites in the surrounding area, such as the ruins of Zeze Castle and Sa of the castle history of Omi Province.
