Many who know him said that Francis, driven by a sense of mission and a discipline born of his early training, essentially worked himself into the hospital.

Pope Francis, who is battling double pneumonia in hospital, had a "tranquil" night and rested, the Vatican said on Sunday.

The death of a sitting pope initiates a profound period of mourning and transition within the Roman Catholic Church, marked by a meticulously structured process to elect a new pontiff