Commentary Purg XX 67-81

And now the really dreadful deeds begin: a descent into the Italian peninsula where a series of members of the French royal house named Charles are given employment by being sent into Italy: Charles of Anjou, who is blamed for killing Conradin (the last hope of Italian Ghibellinism) at Tagliacozzo in 1268 (see [Inf XXVIII 17-18]) and for poisoning Thomas Aquinas in 1274 (a rumor that appears to have been made out of whole cloth as part of Italian anti-French propaganda, but which Dante seems only too willing to propagate).  Then Charles de Valois will take (we are once again in the realm of post-factum prophecy) Florence in 1301 on behalf of an alliance among the French, the papacy of Boniface, and the Black Guelphs of Corso Donati; it is not difficult to imagine Dante's outrage at the intervention of this second Charles.  Finally, the third of these wretched Frenchmen, Charles II, son of Charles of Anjou and king of Naples, is brought on stage to suffer Dante's taunts, delivered by this French version of Dante's ancestor Cacciaguida (see Par. XV-XVII), a benevolent ancestor of (in this case) an undeserving descendant.  This Charles is portrayed as, after having lost a calamitous naval battle during the Sicilian Vespers in 1284 and, as a result, being held prisoner on his own ship, selling his daughter (there having been no intervention from St. Nicholas on his behalf, we may assume) into matrimony with Azzo VIII of Este in 1305.