Ljudevit () or Liudewit (), often also , was the Duke of the Slavs in Lower Pannonia from 810 to 823. The capital of his realm was in Sisak (today in Croatia). As the ruler of the Pannonian Slavs, he led a resistance to Frankish domination. Having lost the war against Franks, he fled to the south, presumably to Dalmatia, first to an unknown Serb župa (a topic of historical debates), and then to the Croat ruler Ljudemisl, who treacherously killed him.
Rebellions against the Franks
In 818 Ljudevit sent his emissaries to Emperor Louis in Heristal. They described the horrors conducted by Margrave Cadolah of Friuli (800-819) and his men in Pannonia, but the King of Franks refused to make peace. Ljudevit raised a rebellion against his Frankish rulers in 819 after he was seriously accused by the Frankish court. The Emperor Louis the Pious (814-840) sent Cadolah to quell the rebellion. The Frankish Frontier forces led by Cadolah have raided the land and tortured the population, most notably the children. As the Pannonian Slavs were amassing forces, so did the Franks led by Cadolah return in 819. But the Frankish forces were soon defeated; and Cadolah himself had to retreat back to his home Friuli, where soon he died of disease.
In July 819 on the Council in Ingelheim Ljudevit's emissaries offered truce conditions, but Emperor Louis refused; demanding more concessions to him. Ljudevit started to gather allies for his plight. His original ally was Duke Borna (Dux Dalmatiae et Liburniae) - the leader of the Guduscani (Gačani), but the Frankish ruler had promised Borna that he would make him Prince of Pannonia if he helped the Franks to crush Ljudevit's rebellion; so Borna accepted. Ljudevit found assistance among the Carantanian and Carniolan Slavs who, as neighbours of the margravate of Friuli, were jeopardized the same as the Pannonians. The Timočani (living around the valley of Timok) also joined him, because they were jeopardized by the neighbouring Bulgars.
The Franks sent a large army led by the new Margrave of Friuli, duke Baldric of Friuli to meet Ljudevit in autumn, the same year while he was conscripting more Carantanian troops along the Drava river. The Frankish forces had numerical advantage, so they pushed Ljudevit and his men from Carniola across the Drava. Ljudevit had to fall back to central parts of his realm. Baldric didn't chase Ljudevit, since he had to pacify the Carantanians. Borna moved with Ljudevit's father-in-law Dragomuž and their forces from the south-west. At the heat of the Battle of Kupa, his own Guduscani abandoned Borna and crossed to Ljudevit's side; while Dragomuž was killed. Borna escaped from the battlefield with the help of his bodyguards.
Ljudevit seized the opportunity and breached into and raided Dalmatia in December. Borna was too weak, so the Dalmatians defended themselves through sneaky tactics and used attrition as their best ally to exhaust the Pannonian forces. Harsh winter came to the hill areas, forcing Ljudevit to retreat. According to Borna's reports to the Frankish Emperor, Ljudevit suffered heavy casualties: 3,000 soldiers, over 300 horses and much food.
War continues
In January of 820, Borna made an alliance with the Frankish Emperor in Aachen. The plan was to crush Ljudevit's realm with a joint-attack from three sides. As soon as the winter retreated, massive Frankish armies were being amassed in Italia, East Francia, Bavaria, Saxony and Alemannia that were going to simultaneously invade Ljudevit's lands in the spring. The northern Frankish group moved from Bavaria across Pannonia to make an invasion across the river of Drava. Ljudevit's forces successfully stopped this Army at the river. The southern group moved across the Noric Alps, using the road from Aquileia to Emona. Ljudevit was successful again, as he stopped them before crossing the Alps. The central group moved from Tyrol to Carniola. Ljudevit attempted to halt its advance three times, but every single time would the Franks win, using numerical advantage. When this Army reached the Drava, Ljudevit had to fall back to the heart of his realm.