Secundum Ticinum
In 758, king Desiderius briefly captured Spoleto and Benevento, but with Charlemagne's conquest of the Lombard kingdom in 774, Arechis II tried to claim the royal dignity and make Benevento a secundum Ticinum: a second Pavia (the old Lombard capital). Seeing that this was impractical and would draw Frankish attention to himself, he opted instead for the title of princeps (prince). In 787, he was forced by Charlemagne's siege of Salerno to submit to Frankish suzerainty. At this time, Benevento was acclaimed by a chronicler as a Ticinum geminum—a "twin Pavia". Arechis expanded the Roman city, with new walled enclosures extending onto the level ground southwest of the old city, where Arechis razed old constructions for a new princely palace, whose open court is still traceable in the Piano di Corte of the acropolis. Like their Byzantine enemies, the dukes linked the palace compound with a national church, Saint Sophia.
In 788, the principality was invaded by Byzantine troops led by Desiderius's son, Adelchis, who had taken refuge at Constantinople. However, his attempts were thwarted by Arechis' son, Grimoald III, who had, however, partially submitted to the Franks. The Franks assisted in the repulsion of Adelchis, but, in turn, attacked Benevento's territories several times, obtaining small gains, notably the annexion of Chieti to the duchy of Spoleto. In 814, Grimoald IV made vague promises of tribute and submission to Louis the Pious, which were renewed by his successor Sico. None of these pledges were followed up, and the decreased power and influence of the individual Carolingian monarchs allowed the duchy to increase its autonomy.
Read more about this topic: Duchy Of Benevento