3 Also at the time Our predecessor Pius XII by word and example incited Us to give Our warmest support to missionary activities and projects. Just before the College of Cardinals was convened for the Conclave during which, by divine inspiration, he was chosen as the successor of St. Peter, he spoke the following words in Our presence: "We cannot expect anything greater or more beneficial from the new Vicar of Christ than these two most important things: that he will strive with all his might to propagate the doctrine of the Gospel among all men, and that he will bring peoples together in a spirit of true peace and strengthen them therein." (4)
Source: Princeps Pastorum (Vatican.va)