 Lefebvre was the first and foremost advisor to Pius XII during the writing of the encyclical "Fidei Donum" (1957), which instructed the clergy and laity on the missions in the Third World countries and called for more missionaries.In 1958 Pope Pius XII died and was succeeded by Pope John XXIII, who, in 1959, after giving Lefebvre the choice between remaining either as Apostolic Delegate or as Archbishop of Dakar, appointed another to the post of Apostolic Delegate for French Africa.Lefebvre continued as Archbishop of Dakar until 23 January 1962, when he was transferred to the Diocese of Tulle in France, retaining his personal title of archbishop.