Sicilian Vespers

It began at Palermo, as the bell was tolling for evening service. The Sicilians had already been involved in furthering their designs against Charles of Anjou, because the Normans, since their occupation of Sicily, had been utter bastards. One of them, a man named Drochet, said something inappropriate to a Sicilian bride. A young Sicilian stabbed Drochet with his sword, and in the ensuing melee, the Sicilians killed ~200 Normans then ran through the street yelling "Let the French die," and went full-out ballistic, killing any Norman they saw.

You may be interested in the book The Sicilian Vespers : A History of the Mediterranean World in the Later Thirteenth Century, by Steven Runciman.

The name commonly applied to a massacre conducted by the citizenry of Palermo on the island of Sicily, in 1282, killing hundreds of French administrators and officers who were stationed in the city. The massacre (which began at Vespers, evening church services, hence the name) was followed by many incidents across the island, bringing the death toll to more than 6000.

The reason for the massacre was widespread dissatisfaction with the harsh regime implemented by Charles I of Anjou, French ruler of Naples. The initially disorganised massacre soon developed into a full-blown insurrection, at the instigation of Peter III of Aragon, who conquered the island later that same year (although the island's new master was not formally acknowledged as such until 1302).

The events of the Sicilian Vespers form the basis of an opera, originally in French, by Giuseppe Verdi, Les Vêpres siciliennes (also known under the Italian title I Vespri Siciliani), first performed in Paris in 1855.