John III of Naples

John III (died late 968/early 969) was the longest-reigning Duke of Naples (928–968). He was the son and successor of Marinus I.

At the beginning of his reign, he warred against the Saracens and then made a treaty with them after they appeared beneath his walls in 929. He then allied with Lombards Atenulf III of Benevento, with whom he signed a pact, and Landulf I, joint-prince of Benevento, against the Byzantines. A Greek force was sent to Apulia and the rebellious vassals were constrained to recognise the authority of the emperor in Constantinople. John then confirmed a treaty with the princes salve fidelitate sanctorum imperatorum.

In 946, he allied with Landulf II of Benevento in an invasion of Salerno with the intent of deposing Prince Gisulf I. They were defeated by an army of Mastalus I of Amalfi and John retired to Naples. Landulf turned around and joined with Gisulf in attacking the Neapolitan duchy. They took Nola.

In 949, John made a donation to the church of Saints Severinus and Sossus, which had possibly been founded by one of his predecessors. In 950, he himself founded the church of Saint Michael Porta Nova in Naples. In 955, he attempted again to throw off the imperial yoke and again an army was sent to Italy under the strategos of Calabria and Langobardia, Marianos Argyros. Refused entry into Naples, it landed in the harbour and pillaged the city, forcing John to submit. In 962, however, John switched his allegiance to the new emperor in the West, Otto I. In 958, Naples was subject to another Muslim siege.

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