When William the Conqueror found himself military master of Britain, he was confronted by a governmental problem quite different from that which has usually accompanied foreign conquest. He did not subdue a nation already organized, substituting his power for that of its former ruler in the conventional way of conquerors. Britain was a geographical unit but politically and socially it was a congeries of loosely related communities. The natural law of survival of the fittest normally operates upon peoples as upon individuals, and develops centralized power as a means of self-preservation. But Britain had a substitute for this. The sheltering sea was a protector more effective than a king's army, and behind the bulwarks of its restless waves the primitive communities of the British Isles went their separate ways and lived their separate lives. With the advent of the Normans all was changed. That hardy line of chieftains developed a most extraordinary genius for government. The task which they persistently held before themselves was the organization of England into a political unit, and their skill and capacity to govern is nowhere better shown than in the instrument chosen for the work of unification. Not the king's soldiers were to bring order out of chaos and power out of weakness. The means to that great end was the king's writ. Private rights in those turbulent times were none too safe, and what could appeal more strongly to the people of England than a king whose strong hand reached everywhere to protect life, liberty, and property! The king's own representative carried the royal summons, the king's court tried the issues and rendered judgment, and behind that judgment was the coercive power of a government which steadily increased in strength as it gained the good will of the people it served. The functionary who carried the royal writ was the sheriff. Since the writ was an original executive writ rather than a judicial writ, the sheriff was the direct agent of the crown, rather than an officer of the court, in making service and entering his return. Service by the sheriff was essential to jurisdiction by the king's court, and no one was liable to suffer judgment unless after notice obtained by the service of the writ.
Sunderland, Edson R. "The Sheriff's Return." Colum. L. Rev. 16 (1916): 281–98.