so-gamae – 日本200名城バイリンガル (Japan's top 200 castles and ruins)

23.Odawara Castle Part3

I introduced the histories and features of Odawara Castle until the Sengoku Period in the previous articles. In this article, I will talk about the histories and features of the castle starting from the Edo Period to the present time. The catchphrase of this article will be “Disaster Recoveries”.

Location and History

Period of Okubo Clan

After the Battle of Odawara Castle in 1590, Ieyasu Tokugawa who captured the Kanto Region chose Edo, not Odawara, as his home. However, he assigned his senior vassal, Tadayo Okubo to Odawara Castle instead as the founder of the Odawara Domain. That meant the castle was still important in order to protect the region from enemies at the western edge of the region. Tadayo lived in the castle while maintaining its stone walls. He used the main hall that the Hojo Clan built, and the Main Tower the clan may have built also. This was because the style of the tower was different from those of the castle later on, but there is no certain evidence of this. Ieyasu often stayed in Odawara Castle when he went hunting or looked around his territories. Despite the close relationship, Tadayo’s successor, Tadachika Okubo was fired by Ieyasu due to a minor violation in 1614. It was actually said that it was caused by the conflicts between the Okubo Clan and the Honda Clan that was another senior vassal family.

The portrait of Tadayo Okubo, owned by Odawara Castle (licensed under Public Domain via Wikimedia Commons)

The portrait of Masanobu Honda, owned by Kaga-Maeda Museum (licensed under Public Domain via Wikimedia Commons)

The image of the first main tower, from the signboard at the site

Period of Inaba Clan

The Odawara Domain was revived in 1632 when Masakatsu Inaba, who was a close vassal of the shogun, became the lord of the castle. He was also a son of Lady Kasuga who was the foster mother of the shogun. Masakatsu was expected to guard the barrier of Hakone near Odawara, which would be the defensive line of the Kanto Region. However, in the following year, Kanei Great Earthquakes happened and it destroyed most of the castle and the castle town. The Tokugawa Shogunate, which planned the shogun’s visit to Kyoto after staying in Odawara in 1634, rapidly launched the reconstructions of the castle. That concluded the basic style of Odawara Castle during the Edo Period. For example, the main tower was rebuilt like the current one, but not the same one. The main portion of the castle was all surrounded by stone walls. The main hall in the main enclosure was built only for the shogun. Therefore, the lord of the castle stayed in his hall in the second enclosure, which was called “Oyakata”.

The portrait of Masakatsu Inaba, owned by Yogenji Temple (licensed under Public Domain via Wikimedia Commons)

The imaginary drawing of Odawara Castle during the Edo Period, from the signboard at the site

The image of the second main tower, from the signboard at the site

The castle town was also developed as a transportation hub of Tokaido Road, one of the main roads in Japan. On the other hand, the range of the castle was reduced to only on the plain land, compared to that during the Sengoku Period. There were exemptions that some of the So-gamae structure were used as borders of the domain or the town. For instance, the eastern gate of the town to Edo, called “Edoguchi-mitsuke” used the So-gamae earthen walls. In the Yamanokami Ditch on the hill, guards monitored the border of the domain at the gate which was built there.

Period of Okubo Clan again

The Okubo Clan became the lord of the Odawara Domain (Odawara Castle) after the Inaba Clan moved to the Takada Domain in 1686. Tadatomo Okubo who was the lord of the clan supported the current shogun as a member of shogun’s council of elders. Few years later, the Genroku Earthquake occurred in 1703 which destroyed the castle and its town again. Mt. Fuji also erupted four years later, which was called “Hoei Eruption”, and its volcanic ash caused serious crop failure to the farms. The castle lost all its main tower and halls, but the shogunate didn’t help the domain in this case. As a result, it took as long as 18 years to restore them except for the main hall for the shogun which was not needed any more. The reconstruction of the main tower was a third generation, which survived until the end of the Edo Period. When the costal defensive system against possible invasions was needed, three batteries were built along the remaining earthen walls of the So-gamae structure beside the sea. However, they were unfortunately demolished until now.

The image of the third main tower, from the signboard at the site

Odawara Castle until Now

After the Meiji Restoration, Odawara Castle was abandoned and most of the castle buildings were scraped. Meanwhile, the stone walls of the main portion were still used as the base of an imperial villa. However, the Great Kanto Earthquakes, which happened on the 1st of September in 1923, destroyed the villa, the stone walls and the only remaining castle building, was the one-level turret of the second enclosure. This disaster had mostly erased the scenery of the remaining castle. The villa was eventually turned into Odawara Castle Park.
People in Odawara started to restore the castle in 1934 by rebuilding the stone walls and the turret of the second enclosure. The 4th main tower and its stone wall base was rebuilt in 1960. Since then, Tokiwagi-mon Gate in 1970, Akagane-mon Gate in 1997, and Umadashi-mon Gate in 2009 were restored to recreate their scenery during the Edo Period. They could be considered one of the disaster recoveries which the castle experienced again and again.

Some of the stone walls of the main enclosure, which collapsed in the Great Kanto Earthquakes

Features

From Third Enclosure to Second Enclosure

Past visitors to the castle would usually enter the castle from the main gate while current visitors would start from Ohoribata Steet beside the moat of the second enclosure. (Ohoribata means “beside the moat”) However, how about if we take another route instead? This route starts from the entrance to the ruins of Kodamon-guchi Gate beside the Odawara post office. It goes on the few remaining earthen walls of the third enclosure to the Ohoribata Street via the gate ruins. This gate had originally been the main gate of the castle during the Sengoku Period. It was said that Kenshin Uesugi attacked the gate first and followed by Shingen Takeda later on.

The ruins of the main gate in the third enclosure, which is used as a bell tower

The moat of the second enclosure was originally a pond surrounding the castle, called “Large Pond” or “Lotus Pond”. The stone walls and the single-level turret over the moat were restored after the Great Kanto Earthquakes. The original stone walls, which were destroyed by the earthquakes, were much higher than the current ones.

The restored stone walls and the single-level turret in the second enclosure

If you enter the front entrance of the Odawara Castle Park, you will enter the Umadashi-mon Gate through the earthen bridge over the moat. This gate was the latest restored gate in the castle, using wooden materials. It has a square space, called Masugata, inside, which makes it tough for enemies to penetrate.

If you pass the gate and walk around the moat again, you will eventually reach the Akagane-mon Gate, which is the front entrance of the second enclosure. You will need to walk across the wooden bridge to go over the moat again, which comes from the castle’s defensive layout. The gate was also restored to its original conditions with the help of old photos, records, and the results of the excavations. This Masugata System looks stronger than The Umadashi-mon Gate, which is surrounded by stone walls and mud walls.

The inside of the second enclosure is mostly an empty space but had the main hall for the lord (during the Edo Period) and the imperial villa (during the Meiji and Taisho Eras).

The space of the second enclosure and the main enclosure just above the hill

Arriving at Main Enclosure

We will eventually reach the main enclosure from the second enclosure through Tokiwagi-bashi Bridge. There used to be the eastern moat surrounding the main enclosure under the bridge, however, it has been converted into an iris garden which you can enjoy if you walk down to the former bottom of the moat. You can also see many hydrangeas planted on the slopes of the enclosure during the summer season.

After crossing the bridge, you will finally enter the last gate, called Tokiwagi-mon. It was restored using concrete instead of wood. The original gate had the Masugata system as well, however, the final restoration lacks one side of the walls probably to make it more accessible for visitors.

There is the reconstructed main tower in the main enclosure. It is very large for a three-level tower which is 27.2m tall and about 39m tall (including the tower base). The tower has four floors inside. It is the seventh tallest main tower among the existing ones in Japan. It is the fourth generation of the main towers of this castle, which was built emulating the miniature model and records of the third generation. However, the fourth generation has the observation platform for visitors on top, which is different from the design of the third generation tower. For this reason, the current tower is regarded not as “restored” but rather “reconstructed”. The inside of the tower is used as a historical museum, which was renovated are reinforced with earthquake-proof technology back in 2016.

The current main tower (the fourth generation)

You can see views of Odawara in all directions from the platform, including where you’ve already visited.

A view from the tower (Hachiman-yama old enclosure)

A view from the tower (the main and second enclosures)

A view from the tower facing west (including Sagami Bay)

Hopes for the Future and Lessons of the Past

If you get out of the main enclosure through the northern exit, you will reach Goyomai Enclosure. (Goyomai means “official stored rice”) Unfortunately, you can not enter it because of the excavations. Instead, you can see the panels around, which showcases what were found there so far. For example, the ruins of a stone pawed garden, including beautiful cut stones, during the Sengoku Period were discovered. The site was turned into warehouses for rice during the Edo Period, which originated the name of the enclosure. I’m looking forward to seeing this site again after it becomes more developed.

The explanation about the stone pawed garden

The explanation about the Tokugawa Shogunate roof tiles

If you go to the southern slopes of the main enclosure, you can see a lot of large stones at the foot which collapsed during the Great Kanto Earthquakes. In fact, the stones were used for the stone walls which covered the top of the enclosure. Some of the stones are still connected to each other forming a curve. That means they slid down from the top to the foot keeping the form when the earthquakes happened. It must have been caused by the enormous strength of the earthquakes. The exhibitions made me realize how important being prepared for disasters is.

The curved stone walls lie down at the foot of the enclosure

Other stone walls which collapsed during the earthquakes

Finally, It may be a good idea to visit the southern moat nearby. It is also known as “lotus moat” which uses the same name during the Sengoku Period. You may be seeing the same scenery as people at that time, which shows the castle has a long history.

My Impression

There are a lot of attractions about Odawara Castle from the Sengoku Period to the present time. Maybe you will need more than one day to see all of them. The lords of the castle achieved many things. For instance, they constructed one of the greatest castles and rebuilt the main towers three times. These works were passed down from one lord to the next. It may look simple, but it is difficult to maintain. I speculate that if another disaster happens in the future to Odawara, people there will survive along with Odawara Castle. They could be a role model for other people under similar situations in the future.

That’s all. Thank you.

Back to “Odawara Castle Part1”
Back to “Odawara Castle Part2”

23.Odawara Castle Part2

I think that the bast way to feel what Odawara Castle was during the Sengoku Period, would be to wak the So-gamae structure. Therefore, this article will show you how to walk around the So-gamae in the current Odawara City.

Features

Rare Remaining So-Gamae structures on Plain Area

Unfortunately, there are only a few remaining structures of So-gamae on the plain city area. First of all, it might y be better to walk the old Tokaido Road to the east. The starting point would be Matsubara Shrine, or a rest station called “Odawarajuku-Nariwai-Koryukan”, which are located at the center of the old transportation hub of Odawara.

It would be more comfortable to go on Kamaboko Street, where there are many traditional Japanese fish cake (which is called Kamaboko) shops are located, which is also similar to the route of the old Tokaido Road during the Sengoku Period. If you walk along the street for a while, you will eventually reach Hojo Inari Shrine. The shrine was built by the Hojo Clan and at the southeast corner of the So-gamae structure.

If you turn left to the north of the shrine, you will soon find the ruins of Edoguchi-mitsuke (which means the gate to Edo). The gate was the eastern entrance of Odawara Transportation Hub during the Edo Period. It was also the Sannoguchi Gate of the So-gamae structure earlier on. Therefore, the partitions of the gate were used until the end of the Edo Period.

In addition, there is also Sanno Shrine, which is little far from the gate ruins, which was a defensive position of the Hojo Clan outside the So-mgamae during the Battle of Odawara. The only direct fighting during the battle happened at this site.

The ground of the shrine looks like a defensive position

If you go on the path beside the gate ruins, you will eventually arrive at one of the few remaining structures of So-Gamae in the city area. It is called, Renjoin Temple Earthen Walls, which is about 100m long and about 3m high. It was originally set with a moat and more defensive than this single unit. You will see a large dent on the walls, which was caused by the Odawara air raid in 1945 during World War II. The ruins had a long history through the multiple periods.

Remaining Structures on the Hill Areas

An easy way to the So-gamae structure on the hill area is to go on the opposite street of a park, called “Medaka-no-gakko”. The street will go up on Yatsu Hill, one of the hill areas behind the Odawara city area. You will eventually find the ruins of Shiroshita-Haridashi. Haridashi refers to the overhanging part of the So-gamae structure. The defenders could have lookout point of the attackers and could counterattack the side from the site. The remaining structure is the base of the overhanging part. That’s why the line forms a right angle.

You can also look around the remaining dry moats along the hill. However, most of them are currently farms now, where visitors are not allowed to enter.

If you continue to go along the street for a while, you will eventually encounter a three-way intersection. Turn right at the intersection, then you will be able to travel on the So-gamae structure easily.

After a while, you will be at Yamanokami-Horikiri. Horikiri refers to a ditch separating a hill in order to avoid the enemies from attacking through the hill. If you go to the bottom edge of the Horikiri, you will find the dry moat of the So-gamae structure touching the Horikiri at right angles. However, the moat is much deeper than the Horikiri. That means the enemies that fell inside the moat, would not be able to invade the Horikiri easily.

Looking at the moat of the So-gamae structure from the edge of the Horikiri ditch

Looking up the earthen walls of the So-gamae structure and the ditch from the bottom of the moats

Next comes Inari-mori (which is the town name). At this site, the earthen walls and dry moats of the So-gamae makes a dent inwards along the natural terrain. The outside of the depression looks like an isolated island. The Hojo Clan also built earthen walls on the island in part to not allow enemies to stay there. This site is one of the most intact parts of the So-gamae structure. The moats managed to keep their original conditions of about 10m deep and over 50-degree slant. This is probably why the visitors are kept out from the moats by ropes and poles.

Large Ditchies of Komine Okane-no-dai, Highlight of So-gamae Structure

The northern part of Odawara City is surrounded by the three hill areas: Hachimanyama, Tenjinyama, and Yatsu. Komine Okane-no-dai hill is part of the Hachimanyama hill area and the highest among the areas. Therefore, the hill was the most important spot for the Hojo Clan in terms of protecting Odawara Castle from invasion. The clan eventually separated the hill by building three ditches. If you walk from the Inarimori Ruins along the So-gamae structure, you will reach the intersection to the three ditches. If you turn right, you will be at the western ditch, left to the eastern ditch, or if you keep going straight, it will lead to the central one.

The western ditch is at the outermost area on the hill, which was originally over 200m long, but is now only 150m long. It was built just before the Battle of Odawara. The ditch seems to get shallower and gentler compared to the original condition. However, if you look at the bottom of it, you can still see something that resembles partitions, which may be the traces of the Shoji-bori system. The edge of the ditch is still connected to the moat of the So-gamae structure.

Next comes the central ditch, which was built at the same time as the western one. The bottom of the ditch is now used as a modern road. You can still see some of the earthen walls around it remaining. A connecting road between this ditch and the eastern ditch still exists.

You will finally arrive at the eastern ditch, which has been developed as a park. You can easily walk the bottom of it. This ditch is the most intact one among the three ditches, which is 280m long and 25 to 30m wide, the same as the original conditions. It is currently 8 to 10m deep, but it was originally about 12m with the Shoji-bori system. Its slant is about 50 degrees, which may be the same as original one, too. The bottom of the ditch is not straight but rather curved, which made it difficult for enemies to walk through smoothly.

The ditch seen from its earthen walls around

Where is the goal of the So-gamae?

You will eventually go down on the hill to the New Moats and Earthen Walls of the Outer Third Enclosure. This place is where Ujimasa Hojo launched the constructions of the So-gamae structure. You can see a great view to the west from there, including Ishigakiyama Mountain where Hideyoshi Toyotomi built his Ishigakiyama Castle during the Battle of Odawara Castle. There is another interesting story where the Hojo side was very surprised to see the completion of Ishigakiyama Castle after all the trees around were cut down, called “Ichiyajo” which means “one night castle” (a castle that only took one night to build). However, the story may be doubtful because the castle ruins can clearly be seen from the site. In addition, please be mindful that the site closes at 3:00 PM, which is much earlier than other historical sites.

The New Moats and Earthen Walls of Outer Third Enclosure

You need to check out the opening hours of the site

You will next walk down to the Tenjinyama hill area. This area also has walls of the So-gamae, called the Earthen Walls, at the west of Denjoji Temple. The walls are located in front of the elevated railways of the Shinkansen (bullet train) and used as a graveyard. If you look up the site from below, you will realize this structure uses natural terrain as well.

After returning to the city area, you should also check out Hayakawa-guchi Ruins (Guchi means entrance or route), one of the few remaining items of the So-gamae structure on the plain area. The Hayakawa-guchi entrance was the front line to the west, where the Toyotomi troops attacked from. Therefore, the entrance was fortified heavily by doubled earthen walls and moats. If you enter the ruins, which have been developed as a park, you will eventually find that the park is sandwiched between the remaining doubled walls.

Other than that, you will be able to find other remaining earthen walls of the So-gamae structure, which are used as the bases of the modern residences along the seaside. If you find one of them, you will be able to understand that these structures were built on such a place and are still intact for the modern facilities to use. This will conclude the tour of the So-gamae structure.

This base of the modern residence uses the earthen walls of the So-gamae structure (its stone walls were probably added later on)

To be continued in “Odawara Castle Part3”

23.Odawara Castle Part1

Odawara was supposed to be the capital of five generations of the Hojo Clan. The city is now supposed to be a popular tourist spot near Hakone hot spring. Odawara Castle first started as a small one in a new post town. The castle eventually grew under the rules of the Hojo Clan to one of the greatest castles during the Sengoku Period. It was finally turned into an important castle at the western edge of the Kanto Region during the Edo Period. The castle was located at the same place through all its life while it changed a lot, which is a very rare case. This article will focus on the history of the castle until the Sengoku Period.

Odawara was supposed to be the main castle for the five generations of the Hojo Clan. The city is now supposed to be a popular tourist spot near Hakone hot spring. Odawara Castle first started as a small one in a new transportation hub. The castle eventually grew under the rules of the Hojo Clan to one of the greatest castles during the Sengoku Period. It was finally turned into an important castle at the western edge of the Kanto Region during the Edo Period. The castle was located at the same place through all its life while it changed a lot, which is a very rare case. This article will focus on the history of the castle until the demise of The Hojo Clan during the Sengoku Period.

The current Odawara Castle, this main tower was rebuilt according to that during the Edo Period

Location and History (until Sengoku Period)

Beginning of the Castle and the Appearance of Sozui Ise

In the ancient time, passengers, who went to the Kanto Region from western Japan, didn’t often use the Hakone Route, but used the Ashigara Route instead. However, they eventually used the Hakone Route when some shrines near the route became more popular. Odawara was first formed as a transportation hub for the passengers not later than the 14th Century. On the other hand, Odawara Castle was thought to be built in the middle of the 15th Century. The Omori Clan, the first lord of the castle, built it in order to collect taxes from the passengers. For this reason, the castle was still small during its early stage.

The location of the castle

As for the location of the castle, it was said that it was first situated at Hachimanyama old enclosure, which is the north of the current Odawara Castle, and further away from the transportation hub. Considering the purpose of the castle, it may have been at the same place as the current one, or at Tenjinyama Hill, closer to the town.

In the beginning of the Sengoku Period, a man named Sozui Ise, became one of the biggest heroes at that time, and later would become a legend. According to the legend, he started only as a Ronin, but eventually became a great warlord, through his own excellent talent. This has been recognized as a big success story of “Gekokujo” which means “giant killer”. However, in recent studies, it was discovered that he was originally a shogunal military guard called Moritoki Ise. He went to Sunpu, which is the current Shizuoka City, to help his sister who was in a dispute about the succession. She was the wife of the Imagawa Clan’s previous lord and wanted her son to be the successor but had to compete with another candidate.

A copy of the portrait of Sozui Ise, owned by Odawara Castle (licensed under Public Domain via Wikimedia Commons)

Sozui (Moritoki) succeeded in the son’s victory. He got Kokokuji Castle as an award of his contribution, which was the beginning of his real success story. The legend also says that Sozui drove the Omori Clan, which was the lord family of Odawara Castle, out from the castle, by tactics known as “Kagyu-no-kei”. Kagyu-no-kei refers to attacking enemies’ bases by using cows with lit torches on their horns. It was said that the statics had been done since the start of ancient China. However, the recent studies argue that it’s not that simple. According to a historical record, Sozui’s brother and the Omori Clan were actually on the same side at Odawara Castle and were defeated by the Uesugi Clan. Historians speculate that Sozui got Odawara Castle when they became enemies, or the castle was damaged because of a huge earthquake around 1500. Sozui was probably not only a hero, but also a practical man and a good negotiator. The castle was still a branch castle even after Sozui got it.

The statue of Sozui at Odawara Station, attacking by Kagyu-no-kei

Improvement of the Castle by Ujitsuna and Ujiyasu Hojo

Sozui’s successor was his son, Ujitsuna Hojo, who was the second generation of the Hojo Clan. However, Ujitsuna was the person who changed his family name from Ise to Hojo. Therefore, Sozui Ise’s well-known alternate name Soun Hojo did not exist while he was alive. Soun was his Dharma name (this is the name given after the person dies). The reason for the change of the family name would be to go against the authority of the Uesugi Clan, the Hojo’s enemy. The Uesugi Clan looked down on the Hojo Clan because they were outlaws from another province. The Hojo Clan needed to improve their own authority in order to attract the local lords by using their new family name. “Hojo” had been the family name of the vice-Shoguns during the Kamakura Shogunate. Ujitsuna also moved his clan’s home to Odawara Castle.

The portrait of Ujitsuna Hojo, owned by Odawara Castle (licensed under Public Domain via Wikimedia Commons)

Ujitsuna’s son, Ujiyasu Hojo was the third generation of the clan. He managed to increase the clan’s territories in the southern Kanto Region, particularly after the victory of the battle of Kawagoe Castle against the Uesugi Clan in 1546. Odawara Castle and its town were becoming the center of the region. The original small transportation hub was turned into the castle town, being as large as that during the Edo Period. The Odawara Water Supply System was installed in the castle and the town. It is said to be one of the earliest water supply systems in Japan. As for the castle itself, the main portion of the castle was built, such as the current main and second enclosures. A priest, who visited Odawara Castle in 1551, recorded that there was a large pond surrounding the castle in three different directions. Part of the pond remains as the moat of the current second enclosure.

A copy of the portrait of Ujiyasu Hojo, owned by Odawara Castle (licensed under Public Domain via Wikimedia Commons)

The moat of the current second enclosure

The first big crisis happened to Odawara Castle in 1561. Kenshin Uesugi invaded the Kanto Region from his home of Echigo Province, which is currently Nigata Prefecture, in order to revive his clan. Kenshin sieged Odawara Castle with his allies and over 100 thousand soldiers the following February (according to the luna calendar). However, the attackers withdrew soon as they did not prepare for a long siege. Ujiyasu Hojo, who was the lord of the clan, avoided fighting against Kenshin but waited patiently for the withdrawal. After Kenshin went back to his home, Ujiyasu got the territories and the retainers in the region back to the same side.

The portrait of Kenshin Uesugi, owned by the Uesugi Shrine (licensed under Public Domain via Wikimedia Commons)

The second crisis occurred in October 1569 (according to the luna calendar). Shingen Takeda from Kai Province, which is currently Yamanashi Prefecture, invaded the Hojo’s territories and reached Odawara Castle on the 1st of October. Shingen first attacked the main gate, called Hasuike-mon (which means lotus-pond gate), and set the castle town on fire. Shingen’s troops also torched the hall of Ujimasa Hojo, Ujiyasu’s successor. Shingen stayed at Odawara for only five days and returned to his home. However, these two crises had a big impact on the Hojo Clan, especially on Ujimasa. When he followed his father’s position, he started to fortify Odawara Castle more and more. He probably thought that if he could build a castle that could withstand a long siege, no enemies would ever destroy it.

The portrait of Shingen Takeda, owned by Jimyo-in, in the 16th century (licensed under Public Domain via Wikimedia Commons)

The portrait of Ujimasa Hojo, owned by Odawara Castle (licensed under Public Domain via Wikimedia Commons)

Goyomai Enclosure, where Ujimasa’s hall was built

Completion of the Castle by Ujimasa and Ujinao Hojo

The Hojo Clan reached its peak in the period of Ujimasa and his successor, Ujinao. This was because Kenshin died in 1578 and the power of the Takeda Clan decreased. The Hojo ruled most of the Kanto Region and built the network of their branch castles to maintain their government. Odawara Castle became the center of it. Ujimasa also fortified the castle. For example, the third enclosure was built on a plain land around the second enclosure. After that, the outer third enclosure was also built on a hill behind the main portion of the castle. They were constructed to protect the castle from potential enemies attacking it from the front and from the back. Furthermore, a large ditch was built to separate the highest hill around the castle, called Komine-Okane-no-dai, next to the outer third enclosure. All of them were made using soil. It was dug to create very steep moats and was mounded to make high earthen walls. The soil around the area came from volcanic ash, which is called Kanto loam layer. It’s naturally slimy, which made enemies slipped when they walk on the surface. The bottoms of the moats were also partitioned forming many square partitions, called Shoji-bori (which means sliding paper door-moat) and Une-bori (which means hilling-moat). If enemies fell to the bottom, they would be trapped and would never be able to escape from it.

The portrait of Ujinao Hojo, owned by Hounji Temple (licensed under Public Domain via Wikimedia Commons)

The large ditch at Komine-Okane-no-dai Hill

The Shoji-bori system in Yamanaka Castle

The development of the castle was related to the situation of the whole country and the diplomatic relations with other warlords. When Nobunaga Oda defeated the Takeda Clan in 1582, the Hojo was forced to be subordinate to Nobunaga. However, Nobunaga was killed during the Honnoji Incident in the same year. The Hojo, Tokugawa, Uesugi Clans battled each other in order to get the former territory of the Takeda Clan. A retainer of the Takeda Clan, the Sanada Clan gained power in order to be an independent lord by interrupting them. As time passed, Hideyoshi Toyotomi became the next ruler, ordering all the lords to stop fighting for themselves. Ujimasa ignored this new movement while other lords followed Hideyoshi by 1587. Ujimasa started a negotiation to serve the Hideyoshi side as well as the following year. One of the problems for the negotiation was about the Numata territory. There has been a dispute as to who was the true owner of the territory, between The Hojo Clan and Sanda Clan. Ujimasa asked Hideyoshi to resolve it. Hideyoshi’s decision was to give two thirds of the territory to the Hojo Clan and the other third to the Sanada Clan.

The portrait of Nobunaga Oda, attributed to Soshu Kano, owned by Chokoji Temple, in the late 16th century (licensed under Public Domain via Wikimedia Commons)

The portrait of Masayuki Sanada, privately owned (licensed under Public Domain, via Wikimedia Commons)

The Portrait of Ieyasu Tokugawa, attributed to Tanyu Kano, owned by Osaka Castle Museum (licensed under Public Domain via Wikimedia Commons)

The Portrait of Hideyoshi Toyotomi, attributed to Mitsunobu Kano, owned by Kodaiji Temple (licensed under Public Domain via Wikimedia Commons)

On the other hand, Ujimasa continued to fortify Odawara Castle in case the negotiations broke down. The highlight of it was to surround the entire area of Odawara including the castle, the town and the hills behind them. This was done by building moats and earthen walls, whose perimeter was about 9km long. This structure is generally called So-gamae (which means outermost enclosure). Ujimasa probably thought that enemies would never enter Odawara, because of this long perimeter, called So-gamae structure.

The red line shows the estimated line of So-gamae structure

The imaginary drawing of the So-gamae structure, from the signboard at the site

In October of 1589 (according to the luna calendar), an incident happened at the Numata territory. The Sanada Clan argued to Hideyoshi that the Hojo Clan forcibly got Nagurumi Castle on the Sanada’s side. This angered Hideyoshi and he finally decided to destroy the Hojo Clan completely. However, there are several questionable points about the incident. Some historians point out that It might have come from a deception of Hideyoshi and the Sanada Clan. Anyway, the battle between them may have been necessary. Hideyoshi wanted more territories to give to his retainers while Ujimasa didn’t want to surrender to Hideyoshi so easily. The So-gamae structure was eventually completed after the two-year constructions before the battle would happen.

Battle of Odawara

In March of 1590 (according to the luna calendar), about 220,000 of soldiers, led by Hideyoshi Toyotomi, rushed into the Hojo’s territories. The number of the Hojo’s defenders was said to be about 80,000. About 50,000 of them were in Odawara Castle. The Hojo Clan probably expected that their enemies would be weakened by the network of the Hojo’s branch castles before they reached Odawara Castle. If they sieged the castle in poor conditions, the Hojo Clan could make peace with them in better conditions. However, most of the Hojo’s soldiers were drafted farmers, nor were they experienced, nor were they trained, and nor were they motivated. The battles occurred on the 28th of March at Matsuida Castle in Kozuke Province (which is currently Gunma Prefecture), and on the 29th at Yamanaka and Nirayama Castles near Odawara. Surprisingly, Yamanaka Castle, which had strong defensive systems like Shoji-bori, was captured in less than one day by the overwhelmingly powerful military force of the Toyotomi side. After that, the castles’ network of the Hojo side eventually collapsed. As a result, only 5 out of tens of the branch castles survived at the end of May. That was the first miscalculation for the Hojo Clan.

The network system of the Hojo’s castles, from the signboard at the site

The Toyotomi’s troops reached Odawara Castle as early as in the beginning of April, surrounding the castle with about 180,000 soldiers. Hideyoshi launched the construction of his new stronghold, which would be called Ishigakiyama Castle, within the month. However, even with huge troops, they were not able to enter the castle, because they were blocked by the So-gamae structure. The structure was 30m wide at max and over 10m deep, with its slope at over 50 degrees. On the other hand, the Hojo side also miscalculated the features of the Toyotomi’s troops. Many of them were professionals and were equipped with enough supply systems. That meant they could survive in their battlefield for a very long time. They reached a much higher level in the combat than those of the Uesugi and Takeda Clans earlier on. As a result, the attackers and the defenders faced each other across the So-gamae structure in April and May.

The war map of Odawara Castle, from the signboard at the site

On the 5th of June, Masamune Date, who was the greatest warlord of the Tohoku Region, arrived at Odawara to serve Hideyoshi. That made the Hojo Clan know that no supporters would help them. The negotiation between the Toyotomi and Hojo sides started behind the scenes. Ujimasa’s successor, Ujinao Hojo was in charge of it. In Japanese, there is a figurative expression called “Odawara Hyojo” which means an inconclusive long conference. People generally think the Hojo didn’t know what to do during the siege. The fact might have been different from it. As time passed, four of the five surviving branch castles were captured in June. Only Oshi Castle was bearing being sieged by the Toyotomi troops like Odawara Castle. Ishigakiyama Castle, which had great stone walls, was completed on the 26th of June as Hideyoshi’s stronghold. Its appearance may have threatened the defenders of Odawara Castle, just a few kilometers away from it.

The portrait of Masamune Date owned by Sendai City Museum (licensed under Public Domain via Wikimedia Commons)

Ujinao finally surrendered to Hideyoshi on the 5th of July. It was said that the negotiation may have included a few territories reserved for the Hojo Clan. However, the decision of Hideyoshi, who completed his unification of Japan, was too strict to allow it. The four leaders of the Hojo side, including Ujimasa, were forced to do Harakiri. Even Ujinao, who made peace with Hideyoshi, was eventually expelled to Koyasan Temple. The Hojo Clan lost everything they had had. Some say that the decision had been planned from the beginning. The territorial allocation after the Battle of Odawara was as followed. Ieyasu Tokugawa moved from around the current Shizuoka Prefecture to the Kanto Region the Hojo Clan had had. Nobukatsu Oda, who was Nobunaga’s son but followed Hideyoshi, was also fired by Hideyoshi due to his rejection to move to Ieaysu’s previous territory. Hideyoshi gave the large vacant territories to his successor, Hidetsugu and his retainers. The satisfied retainers would monitor the actions of Ieyasu who was a potential enemy for Hideyoshi, killing two birds with one stone. In addition, the Sanada Clan got all of the Numata territory after the battle. Were they all coincidental?

The grave of Ujimasa Hojo, near Odawara Station

The Hojo Clan declined but Odawara Castle with the So-gamae structure was very effective against the attackers. For example, it was recorded that Kazuuji Nakamura, who owned Sunpu Castle, built So-gamae structure for his castle, too. In fact, Hideyoshi Toyotomi also built very long earthen walls to surround Kyoto, called O-doi, whose perimeter was about 23 km long. It was recently discovered that the walls had the Shoji-bori system. Hideyoshi also improved his home, Osaka Castle by building So-gamae structure from 1594. Some other lords, who joined the Battle of Odawara, built their own So-gamae as well, probably influenced by Odawara Castle.

The restored stone walls of Osaka Castle, used in its So-gamae structure

To be continued in “Odawara Castle Part2”