Gregory IV was not, in fact, consecrated until the Emperor had signified
his approval of the election.
Outside his own dominions, if Louis appears to have made no attempt to extend his power beyond the limits fixed by Charlemagne, he did at least exert himself to maintain his supremacy over the semi-vassal nations dwelling on all the frontiers of the Empire. For the most part, however, these races seem to have sought to preserve good relations with their powerful neighbour. The respect which, for the first few years of the reign, they entertained for the successor of Charlemagne is proved by the presence at all the great assemblies of ambassadors from different nations bearing pacific messages. At Compiègne, in 816, Slovenes and Obotrites appeared, and again at Herstall (818) and at Frankfort (823); Bulgarian envoys on several occasions; and in 823 two leaders who, among the Wiltzi, were con- tending for power, begged the Emperor to act as arbitrator. Danes were present at l'aderborn (815), at Aix-la-Chapelle (817), at Compiègne (823) and at Thionville (831). Louis even received Sardinians in 815 and Arabs in 816. As to the Eastern Empire, the Basileis seem always to have shewn anxiety to keep on good terms with Louis. On various occasions their ambassadors appeared at the great assemblies held by him; at Aix (817) to settle a question concerning frontiers in Dalmatia; at Rouen in 824 to discuss what measures should be taken in the matter of the controversy concerning images; at Compiègne in 827 to renew their professions of amity. It may be added that it was a Greek, the priest George, who built for Louis the Pious the first hydraulic organ ever used in Gaul.
Even from a military point of view, the reign of Louis the Pious bore at first the appearance of being in some sort a continuation of that of Charles, under a prince capable of repelling the attacks of his enemies. In the north, the Danish race were at this time fairly easily held in awe. One of the rivals then disputing for power, Harold, having been driven out by his cousins, the sons of Godefrid, came in 814 to take shelter at the court of Aix. In 815 the Saxon troops with the Obotrite "friendlies" made an attempt to restore this ally of the Franks to the throne, under , the leadership of the missus Baldric. Promises of submission were made by the Danes, and hostages were handed over, but this was the only result obtained. It was not until about 819 that a revolution recalled Harold to the throne, whence his rivals had just been driven. He retained it until a fresh revulsion of feeling forced him again to take refuge at the court of Louis. On the other hand, in concert with Pope Paschal, Louis had been endeavouring to convert the Danes to Christianity. Ebbo, Archbishop of Rheims, was sent on this mission. Setting out in company with Halitgar, Bishop of Cambrai, he united his labours with those of Anskar and his companions who were already at work spreading the Christian Faith in the district around the mouth of the Elbe, where
