Since the Tomb era, an aristocracy had ruled Japan. It grew and became more elaborate over the centuries, but the essential idea of a hereditary class of noblemen and women administering the islands had remained unchanged. Beginning about 1050, however, the aristocracy—now exclusively civilian in function—was joined by two other elites: the clergy and the military. Each class had its own function, clientele, geographical base, and relation to the sovereign, which in conjunction provided legitimacy for the system. Further, members of each branch formed alliances with the others, and joined together in political factions. These three functionally distinct but politically and socially intertwined elites held sway in Japan until about 1300.
The military was the newest group to attain elite status, but the roots of the samurai lay in the Tomb age. Around 450, the horse had been introduced to Japan from Korea, and when men combined riding the animal with the Jomon technology of archery, a deadly new form of combat was born: mounted archery. Even the small, unneutered horses of early Japan (about one hundred thirty centimeters at the shoulder) made armies more mobile; equestrians could annihilate lightly armored foot soldiers. The two major drawbacks to this form of battle were the great expense of buying and feeding a horse and the large block of time required to learn to ride and shoot from a galloping animal. Typically, a horse cost five times the annual income of a peasant, and would-be mounted archers had to have time to practice. They needed to learn to release the bridle, and guide the on-rushing beast with their legs or voice, all while taking aim and firing arrows. The cost and time invested in mounted warfare meant that it was an occupation limited to local notables and certain members of the service nobility.
Under the Yamato monarch, around 600, armies fighting in Korea or Japan included forces supplied by approximately one hundred twenty local magnates allied to the sovereign, as well as smaller contingents led by the service nobility or from the royal guards. Altogether, these armies may have numbered ten to twenty thousand fighters. The first riders wore iron helmets and slat armor, in which iron pieces were sewn together with leather into flexible sheets. Wielding straight swords, these elite warriors fought alongside foot soldiers employing spears or swords and protected by a cuirass or other armor. During battles, infantry formed lines behind walls of wooden shields.
Beginning in the early 600s, the court feared invasion from either Tang China or Silla and hurriedly adopted a version of the impressive Chinese military system. The main element was a draft of common soldiers, determined through the census and then posted to the local militia. During the winter, these commoner draftees were to drill as units to engage the enemy in the same coordinated way that Tang forces did. Because fighters were responsible for supplying their own weapons, the new system was inexpensive for the government but burdensome for the draftee. Nearly a quarter of adult males were called for service, and the duty was so onerous that there was a saying that “if one man is drafted, the whole household will consequently be destroyed.”
Despite the adoption of the draft from China, the Japanese court retained two crucial elements originating before 650. They designated local notables, at that time usually district magistrates or their kin, to lead armies as cavalry. Even in the late seventh century, the Kanto region was home to the largest number of daring and skillful mounted archers. In addition, certain court families—the Ōtomo, Saeki, and Sakanoue among them—gained reputations as military aristocrats, holding high rank and office.
As described in chapter 3, the Chinese-style army met its stiffest challenge during the wars against the emishi between 774 and 812. The residents of northeastern Honshu were expert mounted archers fighting as guerillas. During the long conflict, the court discovered how inadequate peasant conscript foot soldiers were against the emishi cavalry; there was a dictum that “ten of our commoners cannot rival one of the enemy.”
These long wars helped lay the foundation for the classical samurai way of doing battle. From these small bands of emishi riders, the court learned that leather armor was better suited to mounted warfare and soon abandoned iron. The emishi also wielded a curved sword, instead of the straight one employed by government soldiers. The emishi curved sword was probably the predecessor of the vaunted samurai slashing weapon. Because most engagements involved mounted archers, there were many opportunities for the government’s equestrian elite to hone its skills. In other words, these long wars constituted “practice for becoming samurai.” With the cessation of hostilities in 812, the technology of the samurai had come together: they were lightly armored mounted archers wielding curved swords.