Eugenio Pacelli, the future Pope Pius XII, is ordained a priest. Pacelli will be pope during the period of World War II, forcing him to address issues and problems which few popes have had to deal with.
Although he does make some efforts to halt the coming hostilities (by calling for a peace conference, for example), many believe that his appeasement of Hitler before the war only helped to encourage Hitler's efforts.
Even during the war, he refrains from condemning German atrocities directly and in unequivocal terms. Pacelli's silence in the face of strong evidence of unparalleled atrocities committed by the Nazis against the Jews, despite his obligation as Vicar of Christ to essentially do what Jesus would do, will lead to sharp moral condemnation of both Pope Pius XII and the Vatican generally.