V.He retaliated on the Avars, or Huns of Pannonia, the same calamities which they had inflicted on the nations.

Their rings, the wooden fortifications which encircled their districts and villages, were broken down by the triple effort of a French army, that was poured into their country by land and water, through the Carpathian mountains and along the plain of the Danube.

After a bloody conflict of eight years, the loss of some French generals was avenged by the slaughter of the most noble Huns: the relics of the nation submitted the royal residence of the chagan was left desolate and unknown; and the treasures, the rapine of two hundred and fifty years, enriched the victorious troops, or decorated the churches of Italy and Gaul.

After the reduction of Pannonia, the empire of Charlemagne was bounded only by the conflux of the Danube with the Teyss and the Save: the provinces of Istria, Liburnia, and Dalmatia, were an easy, though unprofitable, accession; and it was an effect of his moderation, that he left the maritime cities under the real or nominal sovereignty of the Greeks.

But these distant possessions added more to the reputation than to the power of the Latin emperor; nor did he risk any ecclesiastical foundations to reclaim the Barbarians from their vagrant life and idolatrous worship.
Some canals of communication between the rivers, the Saone and the Meuse, the Rhine and the Danube, were faintly attempted.