 Summi Pontificatus was the first papal encyclical issued by Pope Pius XII , in October 1939 and established some of the themes of his pontificate . During the drafting of the letter , the Second World War commenced with the German / Soviet invasion of Catholic Poland — the " dread tempest of war is already raging despite all Our efforts to avert it " . The papal letter denounced antisemitism , war , totalitarianism , the attack on Poland and the Nazi persecution of the Church . 
