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Medieval warriors and warfare
Kawai Yasushi, with Karl F. Friday
Japan’s medieval age, stretching from the eleventh century to the close of the sixteenth, was an
era of conflict. From the Genpei War of the late twelfth century to the clashes that marked the
end of the Kamakura shogunate and the Nanbokuchō Wars in the fourteenth, to the cam-
paigns of the sengoku daimyō of the fifteenth and sixteenth, warfare enveloped the country and
steadily advanced in scale and intensity. Historians have been exploring these struggles at
length since the Second World War, analyzing their political meaning within the evolution of
governance and landholding in the countryside and societal transformation. But it has only
been since the 1990s that scholars have turned serious attention on warfare itself, examining
the composition of armies, the structure and shape of battle, the form and usage of weapons
and armor, and the place of war within the evolving warrior- dominated polity of the time.
These new avenues of inquiry have, in consequence, significantly revised our perspectives on
and understanding of the Kamakura and Muromachi shogunates and the development of
warrior rule.
This chapter will outline this new research, with particular attention to the origins of war-
riors, the nature of battle, and the emergence of warrior rule. For reasons of space, our focus will
be primarily on the early medieval period, particularly the Heian and Kamakura eras.
The beginnings of the bushi
The men- at-arms who rode about the battlefields of medieval Japan were known to their con-
temporaries by a variety of names, including bushi, tsuwamono, mononofu, heishi (or hyōji), and
musha, but they are most familiar to modern readers—particularly audiences outside Japan—as
samurai. Indeed, the word “samurai” has entered the lexicons of English and numerous other
Western languages as a synonym for “Japanese warrior.” In origin and premodern usage,
however, the term had a different meaning. Deriving from the verb saburau (“to serve”), it ini-
tially designated middle- ranked court nobles who served as personal retainers to high- ranking
aristocrats or imperial family members. Although some such retainers performed military duties
for their masters, most were civil servants. And while most medieval warriors were also “samurai,”
in the sense that they served overlords, it was their profession of arms, rather than this service per
se, that defined them.