John XXIII (secular name: Angello Roncalli), b 25 November 1881 in Sotto il Monte, Italy, d 3 June 1963 in Rome. As pope his greatest achievement was the calling of the Second Vatican Council, which opened in 1962 and closed after his death. The most important of his seven encyclicals were Mater et Magistra (1961) and Pacem in terris (1963). Through secret diplomacy John secured in 1963 the release from Siberia of Metropolitan Yosyf Slipy, whom in 1960 he had designated cardinal in pectore. Furthermore he appointed Rev Atanasii Velyky secretary of the Preparatory Commission for the Oriental Churches, and then of the Vatican Council Commission for the Oriental Churches. In April 1963 John raised the Ukrainian Minor Seminary in Rome to the status of a pontifical college.
[This article originally appeared in the Encyclopedia of Ukraine, vol. 2 (1988).]