The "Sicilian business" is a historiographical term used to describe the failed attempt by Henry III of England to claim the Kingdom of Sicily for his son Edmund, who had been offered the throne by the papacy. Sicily, established in the twelfth century as a theoretical papal fief, had been ruled by Holy Roman Emperor Frederick II from 1198 until his death in 1250; Pope Innocent IV now sought to install an agreeable sovereign to succeed his longtime adversary. After failed negotiations with Edmund's uncles Richard of Cornwall and Charles of Anjou, the papacy formally offered the throne to the English prince in 1254. For the project, Henry III was tasked with delivering Edmund and armed forces to Sicily to claim it from Manfred, who was serving as regent for Frederick II's grandson Conradin; the papacy was to offer assistance.
A strategic marriage were planned for Edmund; potential brides were the dowager queen of Cyprus or a daughter of Manfred in order to resolve the dispute over the kingdom. Neither union came to fruition, and despite continued attempts to secure support and financing, Henry III's efforts to establish Edmund as the Sicilian monarch faced numerous setbacks. Pope Alexander IV, who had succeeded Innocent IV in 1254, was no longer in a position to effectively finance the project, demanding monetary payment from Henry III as compensation. Finding only minimal support from Parliament and faced with the threat of excommunication from Rome, Henry III resorted to extorting money from his domestic clergy in an attempt to pay the debts. The "Sicilian business" became entangled with broader political troubles in England, and the project ultimately collapsed. Pope Urban IV formally revoked the grant of the Kingdom of Sicily to Edmund in 1263 and instead consigned it to Charles of Anjou, who successfully assumed control of the kingdom in 1266.
The failure of the project has historically been a source of ignominy for Henry III, with contemporary barons in England citing the incident as justification for restricting the monarch's powers. Historians have likewise singled out the incident as one of the motivations for the political upheaval that would occur in England in the years following, but some recent scholarship has questioned this point of view, instead arguing that the mission's lack of success was not entirely the fault of Henry III but rather a consequence of the intricate political situation in Europe.