Siege of Kawagoe Castle

河越城の戦い

Hōjō Clan

Musashi Province

Uesugi Clan

Date:  4/20 of Tenbun 15 (1546)

Location:  Kawagoe Castle and the environs of the Tōmyō Temple in Musashi Province

Synopsis:  The Ōgigayatsu-Uesugi, the Yamauchi-Uesugi, and the Koga kubō branch of the Ashikaga family combined forces to lay siege to Kawagoe Castle defended by Hōjō Tsunanari and a garrison of 3,000 soldiers.  As the siege wore on, the besieging forces became complacent.  This provided an opportunity for a separate division of the Hōjō army to launch a surprise attack resulting in many casualties and causing the Uesugi and Ashikaga forces to flee in disarray. 

Commanders:  Hōjō Ujiyasu, Hōjō Tsunanari, Tame Mototada, Chiba Toshitane

Forces:  11,000 (3,000 in Kawagoe Castle and 8,000 in the Hōjō army)

Losses:  Limited

Commanders:  Uesugi Tomosada, Uesugi Norimasa, Ashikaga Haruuji, various daimyō from the Kantō

Forces:  80,000

Losses:  13,000

The Siege of Kawagoe Castle occurred on 4/20 of Tenbun 15 (1546) in Musashi Province.  This encompasses a series of battles waged in the environs of Kawagoe Castle for control of this pivotal location in Musashi during the Sengoku period.  The battle was waged between the Hōjō clan against the allied forces of the Ōgigyatsu-Uesugi, the Yamauchi-Uesugi, and the branch of the Ashikaga family serving as the Koga kubō and kanrei, or deputy shōgun, of the Kantō.

In an effort to conquer Musashi, Hōjō Ujitsuna, the eldest son and designated heir of Hōjō Sōun and second head of the Gohōjō clan, attacked the base of the rulers of Musashi, the Uesugi clan, at Kawagoe Castle.  Beginning in 1524, clashes for control of the castle occurred on four occasions.

The Siege of Kawagoe Castle is particularly known for the events of 1546 when the foes engaged in a major clash for the fifth time which became a determining factor in the political situation in the Kantō thereafter.  The Nighttime Attack on Kawagoe stands, together with the Battle of Itsukushima and the Battle of Okehazama, as one of the three great surprise attacks in the Sengoku period.

In the Nighttime Attack on Kawagoe, the army of Hōjō Ujiyasu fought against and defeated the allied forces of Uesugi Norimasa, Uesugi Tomosada, and Ashikaga Haruuji near Kawagoe Castle in Musashi.

Background

From the latter part of the Muromachi period, the Koga kubō (the Kantō branch of the ruling Ashikaga family) and the Kantō kanrei (deputy shōgun of the Kantō) opposed one another in a struggle for control over the Kantō Region, an event known as the Kyōtoku Conflict.  In addition, within the Uesugi clan of the Kantō kanrei, a confrontation known as the Chōkyō Conflict arose between the Yamauchi-Uesugi family who, as the main branch of the Uesugi, inherited the role of the Kantō kanrei and the Ōgigayatsu-Uesugi family, an illegitimate branch of the Uesugi, who established a base of power in Sagami and Musashi provinces.  During this time, Hōjō Sōun, based in Sagami in the territory of the Ōgigayatsu-Uesugi, filled the gap by rising to prominence, eliminating the Ōmori and Miura clans who were aligned with the Ōgigayatsu-Uesugi en route to expanding their base of power.  In the midst of the chaos of the Eishō Disturbance involving conflict between the families of the Koga kubō and the Kantō kanrei, Sōun’s son, Hōjō Ujitsuna, advanced into Musashi and toppled Edo Castle.  Next, in 1537, he captured Kawagoe Castle, the base of Uesugi Tomosada, the head of the Ōgigayatsu-Uesugi in a pivotal location in Musashi.  This brought the Ōgigayatsu-Uesugi family to near annihilation.

In 1541, Ujitsuna, however, died and was succeeded by his eldest son and heir, Hōjō Ujiyasu, who became the third head of the Gohōjō clan.  Soon after this succession, Ujiyasu confronted a major crisis.  Toward the end of the seventh month of 1545, Imagawa Yoshimoto, the sengoku daimyō of Suruga Province, colluded with Uesugi Norimasa and launched an invasion of the Hōjō territory in Suruga.  Ujiyasu deployed to Suruga but then the Takeda clan of Kai Province deployed, resulting in a disadvantageous position for the Hōjō.  While on deployment, he further learned that Kawagoe Castle had been surrounded by the massive allied army of the Uesugi families.  As a result, at the end of the tenth month, through the offices of Takeda Harunobu (Shingen), by yielding to Yoshimoto, although humiliating, he was able to reach a settlement.  This event is known as the Second Katō Conflict.  At the beginning of the eleventh month, after exchanging written pledges, the conditions were implemented.  In the midst of a desperate situation with the potential for attacks from two directions, Ujiyasu secured the western front and was able to turn his attention toward battles in the Kantō.

In the Kantō, Ashikaga Haruuji (the Koga kubō and Ujiyasu’s brother-in-law who was married to his younger sister), with the support of the Yamauchi-Uesugi family who served as the Kantō kanrei, or deputy shōgun of the Kantō, changed course, mobilized his forces, and the Yamauchi-Uesugi and Ōgigayatsu-Uesugi families reconciled.  Thereafter, the Uesugi families, together with the family of the Koga kubō, formed an alliance and decided to launch an all-out counterattack against their joint enemy, the Hōjō, as a means to secure Musashi.  With the exception of some of the bushi who were aligned with the Hōjō, orders were given to all of the bushi in the Kantō while Uesugi Norimasa, Uesugi Tomosada, and Ashikaga Haruuji each led their own armies on a march with the aim of recapturing the base of the Hōjō clan at Kawagoe Castle.

Course of events

There is a lack of authenticated accounts with details of the battle written in that period, so the following is based primarily on accounts from military chronicles written in later eras.

On 9/26 of Tenbun 14 (1545), an allied army comprised of Uesugi Norimasa (the Kantō kanrei of the Yamauchi-Uesugi family), Uesugi Tomosada of the Ōgigayatsu-Uesugi family, and Ashikaga Haruuji, (the Koga kubō), and other daimyō based in the Kantō totaling approximately 80,000 soldiers laid siege to Kawagoe Castle defended by the Hōjō clan.  According to one theory, all of the daimyō families in the Kantō (with the exception of Chiba Toshitane of Shimōsa Province) participated in the siege.

Kawagoe Castle was surrounded on three sides, including by Yamauchi Norimasa with a base to the south of the castle and Uesugi Tomosada to the north.  The castle was defended by Hōjō Tsunanari (the younger brother-in-law of Ujiyasu) with a garrison of approximately 3,000 soldiers, but, without reinforcements, it was only a matter of time before the castle would fall.  After ending his battle against the Imagawa, Ujiyasu led 8,000 soldiers from his home province to serve as reinforcements for the castle.  During this time, he succeeded in luring Ōta Sukeaki to the side of the Hōjō, securing the route to the castle.  With an adequate supply of provisions on hand, Tsunanari could hold-out for over one-half year so, for a period of several months, the situation turned into a stalemate.  The prolonged siege undermined the morale of the Uesugi forces and military discipline became lax.  Hōjō Tsunafusa (the younger brother of Hōjō Tsunanari) from the reinforcement army offered to serve as a messenger and, on his own, penetrated the siege by the Uesugi army and entered Kawagoe Castle, informing his brother, Tsunanari, of a plan for a surprise attack.

Ujiyasu offered a fictitious surrender to the allied forces surrounding the castle followed by a letter of apology.  First, he relied upon Suwa Samanosuke to propose to Ashikaga Haruuji that he would vacate the castle on the condition that the lives of the garrison troops be spared.  To the Uesugi, Ujiyasu proposed via a retainer of Oda Masaharu of Hitachi named Sugaya Sadatsugu that if the besieging forces spare the life of Tsunanari, the defenders will vacate the castle and would settle all of the disputes up to now and serve the kubō family.  The Uesugi, however, refused the offer and attacked the Hōjō army instead.  Ujiyasu withdrew his forces to Fuchū without a fight.  As a result, the allied forces of the Uesugi determined that the will of the Hōjō army was low and, with a 10 to 1 advantage in terms of manpower, enjoyed an atmosphere of optimism.

On the evening of 4/20 of Tenbun 15 (1546), Ujiyasu separated his army of 8,000 troops into four battalions.  He had Tame Mototada lead one battalion, ordering them not to move until the fighting ended.  Ujiyasu then led the other three battalions toward the enemy position.  Around midnight, Ujiyasu had the soldiers remove their helmets and wear light clothing and then charged the base of the Yamauchi-Uesugi and Ōgigayatsu-Uesugi forces.  The unexpected attack by enemy forces left the Uesugi forces in disarray.  Among the Ōgigayatsu-Uesugi forces, Uesugi Tomosada (the head of the family) and Nanbada Norishige were killed in action.  Among the Yamauchi-Uesugi forces, Uesugi Norimasa managed to escape the scene and flee in defeat to Hirai in Kōzuke Province, but mainstays of the family including Honma Ōmi-no-kami and Kuragano Yukimasa died while fighting in retreat.  Ujiyasu scattered the Uesugi forces, cutting deeply into the enemy base, but, having observed the battle situation from behind, Tame Mototada sensed danger so he sounded the trumpet shell signaling Ujiyasu’s forces to withdraw.  Having waited in the castle, Tsunanari used this as an opportunity to burst out and, while shouting that they had won, charge the base of Ashikaga Haruuji.  Already prepared to flee, the Ashikaga forces were roundly defeated by the forceful attack by Tsunanari’s army with the survivors escaping to their base in Koga.  A total of 13,000 to 16,000 soldiers from the allied army were killed over a series of clashes.

Consequences

As a result of this battle, the Ōgigayatsu-Uesugi lost the head of their family and were vanquished.  The Yamauchi-Uesugi family of the Kantō kanrei fled in defeat to main base at Hirai Castle but, as an outcome of the battle, witnessed a rapid decline in power.  In an effort to compensate for his weakness, Uesugi Norimasa entered into an alliance with Murakami Yoshikiyo of Shinano Province, aiming to resist the offensive of the Gohōjō army.  Allying with the Murakami clan, however, forced him into opposition against Takeda Harunobu (Shingen).  At the Battle of Otaihara, he further lost a large number of troops.  Amidst these circumstances, one after another, those under his command cut ties with Norimasa and entered into service for the Gohōjō.  Norimasa was expelled from his base at Hirai Castle and turned to Nagao Kagetora (later known as Uesugi Kenshin) of Echigo to flee for safety.

Ashikaga Haruuji (the Koga kubō) who similarly fled in defeat was soon surrounded at his palace and surrendered, after which he retired.  On this event, rather than his eldest son, Ashikaga Fujiuji, Haruuji was compelled to transfer headship of the clan to his second son, Ashikaga Yoshiuji, whose mother originated from the Hōjō.  Haruuji himself then had to live in confinement.

The Hōjō family expanded their sphere of influence in the southwestern portion of the Kantō and solidified their status as a sengoku daimyō.  The forging of a three-way alliance with the Takeda and the Imagawa (known as the Three-Party Alliance between Kai, Sagami, and Suruga Provinces) ended conflict with the Takeda and Imagawa families.  The Hōjō then entered into a struggle against the Uesugi (Nagao) family of Echigo Province who sought to dominate the Kantō in addition to the Satake of Hitachi Province and the Satomi of Awa Province.

As an outcome of this battle, the branch of the Ashikaga family serving as the Kantō kubō definitively lost their position as the Kantō kanrei and military power.  Meanwhile, the Gohōjō clan and other sengoku daimyō expanded their influence.  This meant that the structure that developed during the Muromachi period in the Kantō and eastern provinces was extinguished while the battle cemented the authority of the Gohōjō in the Kantō.

Theories concerning the nighttime assault

The Siege of Kawagoe Castle is recognized as a significant victory in light of an imbalance in troop levels of approximately 10 to 1.  Depending upon the source, however, many details remain uncertain including the date of the battle so further research is required.  In recent years, the prevailing theory is to view the multiple clashes occurring before and after the main battle on 4/20 of Tenbun 15 (1546) as extensions of the same conflict.

Questions regarding whether the defenders holed-up in the castle and the scale of the battle

There are uncertainties concerning the number of troops mobilized by the allied Uesugi and Ashikaga armies, as well as whether there was a nighttime battle.  It has been confirmed, however, through the study of historical accounts that the allied forces outnumbered the Hōjō army and that there was a major clash.

In a later account regarding the course of the conflict, Ujiyasu made reference to victory on both fronts, indicating a connection between the Hōjō forces bursting out of the castle to attack the Ashikaga position as well as the attack by the reinforcements against the Uesugi army.  On the grounds of the Tōmyō Temple which is known as a site of the violent nighttime events stands a monument to the battle and a burial mounds with the remains of fallen soldiers.  During excavation in the Hōreki era (1751 to 1764), the remains of 500 persons were found.  Above these mounds stands the Inari-Suwa Tenman Shrine.  During the nighttime attack on Kawagoe, near the entrance to the Tōmyō Temple, Nanbada Norishige fell into an old well and died so this is for the worship of his soul.  At the time, the Tōmyō Temple had expansive grounds and, dating back to the Kamakura period, the adjacent town flourished.  Owing to the occurrence of the battle in this location, long ago, it was called the Battle at the Entrance to the Tōmyō Temple.  During road construction in the Meiji period, a large number of human remains were discovered in this area.  Concluding these were victims of the nighttime attack presumes there was a nighttime attack.  However, researchers who do not believe there was a large-scale nighttime battle in Kawagoe cite other locations where large-scale tombs have been found in the environs of the Tōmyō Temple such as Yuigahama in the southern portion of Kamakura and Ichinotani in Shizuoka Prefecture.

Theory that there was not a large-scale battle

According to some researchers, there was a large siege and guerilla attacks, but no large clash involving close combat.  The basis for this view is that, on the side of the Gohōjō, there were no written commendations in regard to this battle.  While there is a record of the death of Uesugi Tomosada, there are no details such as who killed him, so there is a possibility that he died of illness at the base.

A letter from Hōjō Ujiyasu notes that 3,000 men were killed at Sunakubo in the environs of Kawagoe where the Yamauchi-Uesugi army was based and that Nanbada Danjō (Norishige) who initiated the battle was also killed.  He did not, however, make reference to a battle at the castle.  Records kept at the Kawagoe Municipal Museum indicate over 2,800 died in battle at Kawagoe, which is consistent with the other sources and much fewer casualties than the prevailing views.  According to this theory, the Hōjō forces at Kawagoe Castle were surrounded by the Uesugi army, but, owing to the sudden death of Uesugi Tomosada, the besieging army dissipated while the large-scale nighttime battle was a fictional portrayal of events contained in works written of later eras.