John of Procida

In that year he went to Viterbo, Italy and arranged the marriage of his daughter to the Neapolitan Guelph, Bartholomew Caracciolo, and then served with the Hohenstaufen army.

His estates were confiscated by Charles; and his wife and daughter were mistreated or raped by the French knight sent to evict them and one of his sons murdered.

[3] In 1279 and 1280 John (or, as Runciman argues, one of his sons at his behest[4]) travelled to Sicily to stir up the discontents in favour of King Peter of Aragon and thence to Constantinople to procure the support of the emperor Michael VIII Palaeologus.

Michael refused to aid the Aragonese king without papal approval and so diplomatic efforts turned to Rome, where he gained the consent of Pope Nicholas III, who feared the ascent of Charles of Anjou in the Mezzogiorno.

Through John's secret diplomatic actions the conditions were set for the 1282 uprising of the Sicilian Vespers which destroyed Charles' crusading invasion fleet (aimed first at recapturing Constantinople) at anchor in Messina, providing the conditions for the security of Constantinople and the ability of Peter III to recover the island.

[5] He is more typically portrayed, particularly by Guelph partisans, as cospiratore contro l'autorità costituita, a "conspirator against the constitutional authority", as in the Tuscan Liber Jani de Procida et Palialoco, which presents him in negotiations with Michael VIII, and in the Leggenda di Messer Gianni di Procida, written by a Modenese Guelph.