Pope Pius XII

Pope Pius XII (Eugenio Giuseppe Pacelli) authored 41 encyclicals and counts as one of only two popes ever to invoke ex cathedra infallibility in declaring the Assumption of Mary, yet his writings remain overshadowed by his involvement in World War II. Pius sought a position of impartiality akin to that of Benedict XV during the First World War. He rejected Allied entreaties to condemn Hitler's campaign against the Jews for fear that the German retribution on Catholics would be devastating. In private, Pius directed Vatican aid to Jewish refugees, but in public, he dismissed pleas from leaders in German-occupied territories to speak out against the Nazi violence. After the War, Pius remained a staunch opponent of expanding Russian influence, issuing a decree of excommunication for any Catholic who joined a communist party. He remains a source of great controversy to this day.