In 1282 Charles of Anjou, brother of French King Louis the Holy, was the most powerful ruler in the Mediterranean. At this moment he was both King of Sicily, Jerusalem and Albania, count of Provence, Forcalquier, Anjou and Maine and ruler of Achaea, Tunisia and senator in Rome. Charles' plans were now to make its power permanent by the conquest of Istanbul.
During the fourth crusade (in 1204) Constantinople had become a Latin kingdom, but already in 1261 it had fallen in Byzantine hands. With the conquest of Constantinople, Charles would become emperor of a new Roman empire. In the spring of 1282 his boats were waiting in the ports of Sicily and he was ready to attack Constantinople during the month of April
During a sermon one afternoon in the Trinity Church of Palermo, a French official, Drouet, treated a Sicilian woman badly. Her husband took a knife and killed Druet. This event triggered a massacre on the French on the island - the Sicilian population rebelled against the French officials on the island and at the end of the day at least 2000 French were dead.
The French were pulled out of their houses. In order to find out if they were Sicilian or French they were forced to pronounce a difficult sentence in local Sicilian language.
Verdi's opera, the Sicilian Vesper, retells the story of the Catalan royal family, which put an end to French domination in the late 1200’s and prevented the Roman the ingestion of Constantinople.
The Sicilian Vesper. A history of the mediterranean world in the later thirteenth century. Cambridge University Press, 1958. (A classic publication that have not been surpassed since its publication more than 50 years ago).