 Pope Pius XII ( Italian : Pio XII ) , born Eugenio Maria Giuseppe Giovanni Pacelli ( Italian pronunciation : [ euˈdʒɛːnjo maˈriːa dʒuˈzɛppe dʒoˈvanni paˈtʃɛlli ] ; 2 March 1876 – 9 October 1958 ) , reigned as Pope from 2 March 1939 to his death in 1958 . Before his election to the papacy , Pacelli served as secretary of the Department of Extraordinary Ecclesiastical Affairs , papal nuncio to Germany ( 1917 – 1929 ) , and Cardinal Secretary of State , in which capacity he worked to conclude treaties with European and Latin American nations , most notably the Reichskonkordat with Nazi Germany , with which most historians believe the Vatican sought to protect the Church in Germany while Adolf Hitler sought the destruction of " political Catholicism " . A pre @-@ war critic of Nazism , Pius XII lobbied world leaders to avoid war and , as Pope at the outbreak of war , issued Summi Pontificatus , expressing dismay at the invasion of Poland , reiterating Church teaching against racial persecution and calling for love , compassion and charity to prevail over war . 
