Gosannen War

Infobox Military Conflict
conflict=Gosannen War
partof=Clan disputes of the Heian period


caption=
date=1083-1089 (disputed)
place=Mutsu province, Tohoku region, Japanflagicon|Japan
casus=Clan disputes over Kiyohara clan leadership
territory=
result=Disputes settled; restored order
combatant1=forces of various branches of Kiyohara clan
combatant2=forces of Minamoto no Yoshiie, Governor of Mutsu province
commander1=Kiyohara no Iehira, Kiyohara no Takahira, others
commander2=Minamoto no Yoshiie, Fujiwara no Kiyohira
strength1=
strength2=
casualties1=
casualties2=

The Gosannen War (後三年合戦, "gosannen kassen"), also known by the English translation Later Three-Year War, was fought during Japan's Heian period in the province of Mutsu at the far north of Japan's main island of Honshū. Though some scholars date the war to the period of 1086 to 1089, others place it a few years earlier, lasting from 1083 to 1087. Like the Zenkunen War that preceded it, and the various conflicts that were to follow, the Gosannen War was a struggle for power within the competing warrior clans of the time.

In this particular case, it was a series of quarrels within the Kiyohara clan (sometimes referred to as "Kiyowara"), resulting in large part from relationships of branches of the clan with other clans, many through marriage. These quarrels, and the associated disturbances, eventually reached the point that external interference became necessary. Minamoto no Yoshiie, who became Governor of Mutsu province in 1083, sought to quell the fighting between Kiyohara no Masahira, Iehira, and Narihira, the heads of the various branches of the family.

His early diplomatic efforts made some progress, but were not enough to stifle the fighting, and so Yoshiie brought in his own warriors. At first he supported Kiyohara no Iehira and his half-brother Fujiwara no Kiyohira against Kiyohara no Sanehira, but after Sanehira's death, Yoshiie and Iehira turned on one another.

Yoshiie attacked Iehira in the fortress at Numa, but was unable to penetrate the defenses; Yoshiie lost many men to the cold and lack of supplies.

Iehira then established a warrior camp around Yoshiie's fortress at Kanezawa, along with the forces of his uncle Kiyohara no Takahira. After a period of inactivity and relative peace, Yoshiie launched a siege on this encampment, along with his brother Minamoto no Yoshimitsu, who had arrived from Kyoto. Approaching the fortress, Yoshiie is said to have noticed a flock of cranes emerging hastily and disorderedly from the forest, indicating to him that an ambush had been set among the trees. The siege was drawn out for several months, but was eventually successful after an assault on the fortress with the aid of Fujiwara no Kiyohira.

Much of the war is depicted in an "e-maki" narrative handscroll, the "Gosannen Kassen E-maki", owned today by the Watanabe Museum in Tottori city, Japan.

References

*Sansom, George (1958). 'A History of Japan to 1334'. Stanford, California: Stanford University Press.
*Turnbull, Stephen (1998). 'The Samurai Sourcebook'. London: Cassell & Co.