The form of government Yoritomo instituted is generally, if somewhat inaccurately, described as feudalism. The provincial warrior families managed estates worked by peasants whose role was similar to that of the European serfs of the same period. The estate-owning barons were mounted warriors, new figures in Japanese history, who protected their lands and their family honor much as did the European knights. But instead of glorifying chivalry and maidenly honor, they respected the rules of battle and noble death. Among the fiercest fighters the world has seen, they were masters of personal combat, horsemanship, archery, and the way of the sword. Their principles were fearlessness, loyalty, honor, personal integrity, and contempt for material wealth. They became known as _samurai_, and they were the men whose swords were ruled by Zen. Battle for the _samurai_ was a ritual of personal and family honor. When two opposing sides confronted one another in the field, the mounted _samurai_ would first discharge the twenty to thirty arrows at their disposal and then call out their family names in hopes of eliciting foes of similarly distinguished lineage. Two warriors would then charge one another brandishing their long swords until one was dismounted, whereupon hand-to-hand combat with short knives commenced. The loser's head was taken as a trophy, since headgear proclaimed family and rank. To die a noble death in battle at the hands of a worthy foe brought no dishonor to one's family, and cowardice in the face of death seems to have been as rare as it was humiliating. Frugality among these Zen-inspired warriors was as much admired as the soft living of aristocrats and merchants was scorned; and life itself was cheap, with warriors ever ready to commit ritual suicide (called _seppuku _or _harakiri_) to preserve their honor or to register social protest. Yoritomo was at the height of his power when he was killed accidentally in a riding mishap. Having murdered all the competent members of his family, lest they prove rivals, he left no line except two ineffectual sons, neither of whom was worthy to govern. The power vacuum was filled by his in-laws of the Hojo clan, who very shortly eliminated all the remaining members of the Minamoto ruling family and assumed power. Not wishing to appear outright usurpers of the office of shogun, they invented a position known as regent, through which they manipulated a hand-picked shogun, who in turn manipulated a powerless emperor. It was an example of indirect rule at its most ingenious.