Sicilian separatist Salvatore Giuliano and his gang fired into a crowd of May Day marchers near Piana degli Albanesi, Sicily, killing 11 and wounding 33.

Salvatore Giuliano was an Italian brigand, who rose to prominence in the disorder that followed the Allied invasion of Sicily in 1943. In September of that year, Giuliano became an outlaw after shooting and killing a police officer who tried to arrest him for black market food smuggling, at a time when 70 percent of Sicily's food supply was provided by the black market. He maintained a band of subordinates for most of his career. He was a flamboyant, high-profile criminal, attacking the police at least as often as they sought him. In addition, he was a local power-broker in Sicilian politics between 1945 and 1948, including his role as a nominal colonel for the Movement for the Independence of Sicily. He and his band were held legally responsible for the Portella della Ginestra massacre, though there is some doubt about their role in the numerous deaths which occurred.

The Portella della Ginestra massacre refers to the killing of 11 people and wounding of 27 others during May Day celebrations in Sicily on 1 May 1947, in the municipality of Piana degli Albanesi. Those held responsible were the bandit and separatist leader Salvatore Giuliano and his gang, although their motives and intentions are still a matter of controversy.

May Day is a European festival of ancient origins marking the beginning of summer, usually celebrated on 1 May, around halfway between the Northern Hemisphere's spring equinox and midsummer solstice. Festivities may also be held the night before, known as May Eve. Traditions include gathering green branches and wildflowers, which are used to decorate buildings and made into wreaths; crowning a May Queen, sometimes with a male companion decked in greenery; setting up a Maypole, May Tree, or May Bush, around which people dance and sing; as well as parades and processions involving these. Bonfires are also a major part of the festival in some regions. Regional varieties and related traditions include Walpurgis Night in central and northern Europe, the Gaelic festival Beltane, the Welsh festival Calan Mai, and May devotions to the Blessed Virgin Mary. It has also been associated with the ancient Roman festival Floralia.