officials sent by some Frankish kings and emperors to supervise provincial administration. Used sporadically by Merovingian and early Carolingian rulers, the missi became a normal part of the administrative machinery under Charlemagne (reigned 768–814). From about 802 onward almost all of his empire was periodically divided into missatica, or inspection circuits; these were visited—in theory for four months out of every year but often in practice less regularly—by at least two missi, one a bishop or abbot, the other a layman, probably a count. The missi were powerful men protected with a wergild (price paid to a slain man's relatives) equal to that of a member of the sovereign's family. They had full investigatory powers and were to rectify all error and injustice. Missi administered the oath of allegiance exacted from all freemen on the occasion of a new sovereign, informed local communities of the content of imperial decrees, and reported back on local conditions and needs. The difficulties that beset the Carolingian empire after about 830 paralyzed and finally virtually destroyed the system of missi dominici by the end of the 9th century.