of the Taira and the Minamoto as viewed by the court was to protect the
interests of the imperial and other court families in the countryside where
they held lands. However, Taira and Minamoto warriors soon became the
military arm of individual court families, namely the Fujiwara and the im-
perial families, who were competing for power at court. Changing rivalries
and shifting alliances eventually led to military conflicts and to a change in
the characteristics of warfare.
The tenth century marked a transition in the Japanese military, as re-
flected in the revolts of Taira no Masakado in the Kantô region and Sumi-
tomo in western Japan between the years 935 and 940, during which time
economic difficulties and unstable politics had weakened the court.
Masakado, whose initial reason for armed uprising was his uncle’s refusal to
marry his daughter to Masakado, also targeted the court. Though Masakado
directed his attacks at the court, his revolt was primarily for the purpose of
establishing his lineage within the Taira clan. Thus, a new era in Japanese so-
ciety and warfare began with the use of military actions to resolve intrafa-
milial rivalries. Masakado’s tactics relied on existing Chinese-influenced
methods of fighting, but his superior organization, technology, and strategy
allowed him to defeat his rivals. Similarly, Sumitomo, a pirate leader in west-
ern Japan, heard of Masakado’s revolt and used the opportunity of a weak-
ened court to expand his activity to such an extent that the Kyoto court felt
seriously threatened. Instead of fighting both rebels simultaneously, the court
first targeted Sumitomo by offering him a high court rank in return for his
allegiance. After Sumitomo accepted the offer, the court sent Taira and Fuji-
wara forces to seek and destroy Masakado and his allies. In 940 Masakado
forces in eastern Japan were destroyed, and Sumitomo in western Japan be-
came a member of the court. Nevertheless, both men left their mark on the
evolution of warfare, making it more sophisticated and professionalized.
Four major military conflicts occurred between 1056 and 1160 in-
volving Taira and Minamoto warriors. The first war, known as The For-
mer Nine Years War (lasting from 1056 to 1062, it was in fact only six
years long), took place between Minamoto-led forces and the Abe family
in the Tôhoku region. The second war, known as The Latter Three Years
War (lasting from 1083 to 1087, it was actually four years long), was be-
tween the same Minamoto warriors and the Kiyowara family from the
same region, who in The Former Nine Years War had been allied with the
Minamoto. The purpose of these wars was to restore control of their lands
in the Tôhoku region. Remaining records related to the wars show that
warfare in Japan was further progressing toward smaller groups of profes-
sional warrior bands. Siege warfare and mounted combat replaced large
armies of foot soldiers who fought in rigid formations, and war technology
shifted toward a more extensive use of the bow and arrow (yumiya).
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