Battle of Yanagare

八流の戦い

Chōsokabe Clan

Tosa Province

Aki Clan

Date:  Seventh month of Eiroku 12 (1569)

Location:  Yanagare in Tosa Province

Synopsis:  After Aki Kunitora spurned an invitation from Chōsokabe Motochika to visit Okō Castle, the two armies clashed at Yanagare.  Despite waging the fight, the Aki army collapsed from within owing to defections by retainers, causing forces to flee their positions and Kunitora to ultimately sacrifice himself after turning over Aki Castle. 

Commanders:  Chōsokabe Motochika, Fukudome Chikamasa

Forces:  7,000 (3,000 regular forces and 4,000 jizamurai)

Losses:  Unknown

Commanders:  Aki Kunitora, Kuroiwa Echizen

Forces:  5,000

Losses:  Unknown

The Battle of Yanagare occurred in the seventh month of Eiroku 12 (1569) and was waged by Chōsokabe Motochika and Aki Kunitora in Tosa Province in Shikoku.

Prelude

Over a period of time, tensions grew between the Chōsokabe clan governing central Tosa and the Aki clan governing eastern Tosa.  In 1563, when Chōsokabe Motochika deployed with the aim of subduing the Motoyama clan, Aki Kunitora took advantage of this opportunity to attack Motochika’s main base at Okō Castle.  Owing to the defense led by Fukudome Chikamasa, Kunitora’s forces were repelled in an event known as the Fukudome aragiri, or the cutting through of the enemy by vanguard forces.  After re-grouping his forces, Motochika headed out to conquer the Aki clan, but, through the mediation of Ichijō Kanesada, the two sides reached a settlement.

Early in the fourth month of 1569, Motochika dispatched a messenger inviting Kunitora to visit Okō Castle to deepen their relationship.  Kunitora, however, misinterpreted the communication, turning away the messenger saying that the invitation was highly imprudent.  Ignoring the appeals of a senior retainer named Kuroiwa Echizen, Kunitora breached the settlement and, together with Kanesada, attempted to subdue Motochika.

Course of events

By this time, Motochika had already conquered the Motoyama clan and increased his military strength.  In the seventh month, Motochika led 7,000 troops (comprised of 3,000 regular troops and 4,000 jizamurai, or local fighters) to invade the territory of the Aki clan, establishing a position in Wajiki.  Kunitora responded by leading 5,000 troops to reinforce their defenses at Aki, Shinshō, and Ananai castles and making a camp at Yanagare.

The Chōsokabe army split into two divisions, with Fukudome Chikamasa leading one division of 5,000 members along the coastline and Motochika leading the other division of 2,000 members to attack on an inland route.  At Yanagare, the forces led by Chikamasa collided with 2,000 forces in the Aki army led by Kuroiwa Echizen.  Although Echizen took advantage of his advantageous land position to gain the upper hand, the Aki army had already began to collapse from within and fled the battlefield and from the castles that were under Aki control.  Meanwhile, Motochika’s main division succeeded in attacking the Aki army from behind, sending this division of 3,000 forces to Aki Castle.

At the Battle of Yanagare, Kunitora was defeated and, before long, the castles were toppled.  Kunitora then holed-up in Aki Castle, but many of his hereditary retainers, including Odani Sakonemon, colluded with Motochika so he was no longer able to mount a defense.  After resisting for twenty-four days, the provisions ran low, from 2,000 to 3,000 reinforcements expected from the Ichijō clan failed to show, and other incidents, including a poisoning of the well on the castle grounds by Yokoyama Minbu, led to the imminent fall of the castle.  Kunitora offered to Motochika to take his own life in exchange for sparing the lives of his retainers and the villagers.  After further agreeing to send his formal wife back to the Ichijō clan in western Tosa and leave behind his to-be orphan, Senjumaru, in Awa Province, on 8/11, he took his own life in the family temple known as the Jōtei Temple.  He was forty years old.  In the wake of his death, many of his senior retainers followed by martyring themselves.

With this victory, Motochika had pacified all of Tosa Province with the exception the western portion governed by the Ichijō clan.