Battle of Shirakobara

白子原の戦い

Ōgigayatsu-Uesugi

Musashi Province

Hōjō Clan

Date:  8/22 of Daiei 5 (1525)

Location:  Shirakobara in the Niira District of Musashi Province

Synopsis:  Following a settlement between Uesugi Norifusa of the Yamanouchi-Uesugi family and Uesugi Tomooki of the Ōgigayatsu-Uesugi family, Tomooki came into conflict with Hōjō Ujitsuna which spread across Musashi Province.  In a violent battle at Shrakobara, Tomooki eventually defeated Ujitsuna, but subsequent conflicts among the Uesugi allowed the Hōjō to avoid decimation.

Commanders:  Uesugi Tomooki

Forces:  Unknown

Losses:  Unknown

Commanders:  Hōjō Ujitsuna

Forces:  Unknown

Losses:  Over 800

The Battle of Shirakobara occurred on 8/22 of Daiei 5 (1525) in Shirako in the Niikura District of Musashi Province.

At the beginning of the Daiei era (1521 to 1528), Ashikaga Takamoto and his younger brother, Ashikaga Yoshiaki (later the Oyumi kubō), came into conflict regarding the successor to the Koga kubōUesugi Norifusa of the Yamanouchi-Uesugi family backed Takamoto to fight against Uesugi Tomooki, a daimyō and head of the Ōgigayatsu-Uesugi family and Ise Ujitsuna of the Ise clan (later becoming the Hōjō clan), a sengoku daimyō and the second head of the Gohōjō clan, supporting Yoshiaki.

In the first month of 1524, Norifusa and Tomooki settled.  Ujitsuna, however, opposed the settlement and attacked Edo Castle.  This is known as the Battle of Takanawahara.  The conflict between Tomooki (with the support of Norifusa) and Ujitsuna spread across Musashi.  In particular, violent clashes occurred for control of Iwatsuki and Kasai castles in the vicinity of Edo Castle.  After Kasai Castle fell to the Hōjō (having changed their surname from Ise), and fearing the expansion of Ujitsuna’s influence, Yoshiaki supported Tomooki, leaving Ujitsuna in a difficult situation.

Nevertheless, in the second month of 1525, after incurring a counterattack from Ujitsuna, Ōta Sukeyori lost Iwatsuki Castle and temporarily withdrew to Ishido Castle.  This is known as the Siege of Iwatsuki Castle.  Ujitsuna then aimed to advance into northern Musashi while Tomooki sought to forcibly take back southern Musashi by forging an alliance with Norifusa (his former archenemy), Takeda Nobutora (a sengoku daimyō and the military governor of Kai who fought against the Hōjō in the Tsuru District of Kai), and Mariyatsu Jokan (a sengoku daimyō from Kazusa Province). 

In the third month, Uesugi Norihiro (the adopted son of Norifusa) supporting Tomooki toppled Shōbu Castle in the Saitama District of Musashi which was aligned with the Hōjō.  These events culminated in the Battle of Shirakobara.

After a furious battle between Tomooki and Ujitsuna at Shirakobara, the Uesugi army prevailed while the Hōjō army incurred over 800 losses including Ise Kurō, the representative of Ujitsuna.  Ise Kurō is identified in historical materials as Kushima Kurō.  Under one theory, he was the father of Hōjō Tsunshige and originally a member of the Fukushima clan serving as retainers of the Imagawa.  Ise Sōzui (Hōjō Sōun) served as a guest commander of the Imagawa, so Kurō later followed him to the Kantō, became his retainer, and was given the Ise surname.

In the fifth month of 1526, Tomooki assaulted Warabi Castle and, at the same time, Ashikaga Yoshiaki, together with Satomi Yoshitoyo, attacked the Hōjō territory from the sea.  In the eleventh month, both Uesugi armies advanced to Kugenuma and Tamanawa Castle in Sagami Province.  This series of offensives by the Uesugi armies posed challenges for the Hōjō, but after entering the Kyōroku era (1528 to 1532), a struggle erupted between the Yamanouchi-Uesugi and the Koga kubō for headship of the clan, allowing the Hōjō to escape their predicament.  This event is known as the Kantō Kyōroku Conflict.