Reassessing the First Byzantine-Lombard Plan To Restore Adelchis In 775–776: The Plot That Never Was?

Abstract This article reassesses Pope Hadrian’s claim that a Byzantine-Lombard conspiracy was underway in 775-776 to overturn Charlemagne’s rule in Italy, seize Rome, and restore Adelchis as king of the Lombards. The credibility of this claim is strengthened by parallels with the similar Byzantine-Lombard plot of 787-788, which did materialize. Additionally, an overlooked passage in the Deeds of the Bishops of Naples independently confirms that Constantine V was preparing an Italian expedition shortly before his death. This evidence suggests that the 775-776 plot was a serious effort to challenge Frankish dominance in Italy and reassert Byzantine authority in Rome. However, its failure was ultimately due to the uncertainties caused by Constantine V’s sudden death, coupled with the successful diplomatic maneuvering of Charlemagne’s envoys in central and southern Italy.