Unione Corse was the general name given by the American authorities to the major Corsican gangs who organized the French Connection, a heroin trade between France and the United States from the 1950s to the early 1970s. The Corsican gang, led by the Guerini brothers (Antoine and Barthélémy, nicknamed "Mémé"), was exempt from prosecution in Marseilles from the 50's to the 60's. The Guerini brothers were trafficking opium derivatives illegally imported from French Indochina using the services of the Messageries Maritimes, a French merchant shipping company. During World War II, the Guerini brothers had sided with the Gaullist part of the French Resistance, while the pre-war crime kings of Marseilles, Paul Carbone and François Spirito, had sided with Vichy and the Germans. In 1947, Marseilles had a communist mayor, Jean Christofol, who was backed by the trade unions. He was popular among longshoremen, transportation, and dockworkers. He was opposed by socialist candidate Gaston Deferre, who later became mayor of Marseilles for almost three decades. In the coming Cold War both the center-left French government and the US tried to fight communist influence in Marseilles while occasionally employing illegal means to further their goal. Marseilles was, at the time, the main trading port of the French colonial empire. The Guerini gang was employed to disrupt union and electoral gatherings, back strikebreakers and support US-funded non-communist trade unions. The killing of a young trade unionist, Vincent Voulant, in 1947 is attributed to the Guerini mob, though the case was never finalized.
The end of the French Connection caused the disbandment of many Corsican clans involved in the heroin trade. However, the evolution of Corsican Mafia has continued in several illegal activities (hold-ups, racketeering, casinos, illegal slot machines, various drug dealing and prostitution). From the 1980s to the end of 2000s, the Corsican mafia was split into two major groups; the Brise de Mer, based in Northern Corsica, and the Colonna clan (also named "Jean Jé Colonna's family"), based in Southern Corsica. In 2007 a violent internal conflict troubled the Corsican mafia, resulting in around 102 murders on the island of Corsica. This conflict caused the fall of these two groups and the rise of new Corsican gangs. Today, the Corsican mafia consists of multiple families, allies, and rivals. Known groups in the Corsican mafia are the Venzolasca gang, considered the Brise de Mer successors, the "Petit Bar" gang (also called the "Little Bar"), the Valinco mobsters, and the Corsican mob of Marseille.