One curious, though not immediate, result of the rapidly increasing estrangement between Franks and Greeks was that in the great synod which Charles held at Frankfurt in 794 for the condemnation of the “Adoptian heresy,”[58] Charles induced his bishops to pass a severe condemnation of “the synod held a few years before under Irene and her son which called itself the Seventh Ecumenical Council, but which was neither the seventh nor ecumenical, but was rejected by all present at Frankfurt as absolutely superfluous.” At the same time it was declared by the assembled bishops that neither worship nor adoration was to be paid to the images of the saints. Thus was Charles, the great patron and defender of the papacy, actually brought into controversy with the pope on an important point of Christian practice.
The immediate effect of the rupture of the marriage treaty was seen in an invasion of Italy by the Greeks, in which at last the long lingering Adelchis took part. The intention was to make an attack on Charles’s dominions in combination with the Prince of Benevento (on whom the dignity of patrician was conferred) perhaps also with Tassilo the Bavarian; but before the Imperial troops landed in Italy, Arichis of Benevento was no more. He died on the 26th of August 787, a man still in the flower of his age. It is striking to observe how much Charles’s upward course to empire was facilitated by the opportune deaths of his competitors. Carloman, Constantine V., Leo IV., and now Arichis of Benevento, all died at the most seasonable time for the success of Charles’s projects. At the time of the death of Arichis, his son and heir Grimwald III. was in Charles’s keeping as a hostage. Pope Hadrian earnestly besought the king never to permit one of the God-hated dynasty to ascend the Beneventan throne, but Charles, after some delay, allowed Grimwald to return and take his place in the palace of Benevento. He was, however, compelled to promise to pay a yearly tribute of 7000 _solidi_, to coin money with Charles’s effigy, to date his charters by the years of the Frankish king, and in all things to acknowledge him as his over-lord. For the present these conditions were kept, and at the crisis of the Byzantine invasion Grimwald III. comported himself as a loyal vassal of Charles. So it came to pass that when at last the Byzantine troops landed in Calabria they were met by the united forces of the Frankish king under his general Winighis, and the Lombard dukes of Spoleto and Benevento. The defeat of the Greeks was crushing (788). Four thousand of their warriors were slain, among them the _sacellarius_ John, commander of the expedition; and one thousand were taken prisoners. Adelchis appears to have made his escape. He reappeared no more on the soil of Italy, but died many years after, an elderly, probably a wealthy, patrician at Constantinople. This last scion of the Lombard kings is not an interesting figure in history.