wife before the Church of the Holy Spirit on Easter Monday (30March), 1282. When the soldier's comrades attacked the murderer, the mob turned against them and started to massacre all the French in the town. The riot, known since the 16th century as the Sicilian Vespers, developed into an uprising and most of Charles's officials were killed or forced to flee the island. Charles ordered the transfer of soldiers and ships from Achaea to Sicily, but could not stop the spread of the revolt to Calabria. San Severino also had to return to Italy, accompanied by the major part of the garrison at Acre. Odo Poilechien, who succeeded him in Acre, had limited authority. The burghers of the major Sicilian towns established communes which sent delegates to Pope Martin, asking him to take them under the protection of the Holy See. Instead of accepting their offer, the Pope excommunicated the rebels on 7May. Charles issued an edict on 10June, accusing his officials of having ignored his instructions on good administration, but he failed to promise fundamental changes. In July he sailed to Sicily and laid siege to Messina. War with Aragon Peter III of Aragon's envoy, William of Castelnou, started negotiations with the rebels' leaders in Palermo. Realizing that they could not resist without foreign support, they acknowledged Peter and Constance as their king and queen. They appointed envoys to accompany Castelnou to Collo where the Aragonese fleet was assembling. After a short hesitation, Peter decided to intervene on the rebels' behalf and sailed to Sicily. He was declared king of Sicily at Palermo on 4September. Thereafter two realms, each ruled by a monarch styled king (or queen) of Sicily, coexisted for more than a century, with Charles and his successors ruling in southern Italy (known as the Kingdom of Naples) while Peter and his descendants ruled the island of Sicily. In the face of the Aragonese landing, Charles was compelled to withdraw from the island, but the Aragonese moved swiftly and destroyed part of his army and most of his baggage. Peter took control of the whole island and sent troops to Calabria, but they could not prevent Charles of Salerno from leading an army of 600 French knights to join his father at Reggio Calabria. Further French troops arrived under the command of Charles's nephews, Robert II of Artois and Peter of Alençon, in November. In the same