Pius XI (secular name: Ambrogio Damiano Achille Ratti), b 31 May 1857 in Desio, Italy, d 10 February 1939 at the Vatican. Pope of the Catholic church in 1922–39. As papal nuncio in Poland (1919–21) he intervened against Polish assaults on the Ukrainian Catholic church following the occupation of Galicia (see Ukrainian-Polish War in Galicia, 1918–19). Later he oversaw the conclusion (1925) of a concordat to regulate relations between Ukrainian and Polish Catholics in Galicia; this agreement, however, did not extend to Volhynia, and the Ukrainian hierarchy had no authority there. He also sought to shore up the Ukrainian church hierarchy in Czechoslovakia, Romania, Canada, Brazil, and the United States. Other initiatives during his papacy included the building of Saint Josaphat's Ukrainian Pontifical College in Rome (1931), the transfer of the Basilian monastic order’s administrative center to Rome and the addition of Hungary and Romania to its jurisdictions, and the establishment of a pontifical commission for the codification of Eastern church rite canon law (1935).

[This article originally appeared in the Encyclopedia of Ukraine, vol. 4 (1993).]