sentences:  After the death of Charlemagne in 814, Frankish influence decreased on the region, allowing Prince Ljudevit Posavski to raise a rebellion in 819.The Frankish margraves sent armies in 820, 821 and 822, but each time they failed to crush the rebels.Aided by Borna the Guduscan, the Franks eventually defeated Ljudevit, who withdrew his forces to the Serbs and conquered them, according to the Frankish Annals.