Introduction -- ´Usseless slaughter´: benedici XV and the first world war -- Benedict XV: the post-war world and the church -- Pius XI: Italian Francism and the conciliazione -- Pius XI: the teacher and his church --The ´foreign policy´ of Pius XI in the 1920 -- Pius XI and the dictators, 1930-9 -- Pius XII peace diplomacy and war -- Pius XII war and Fascist Genocides -- Pius XII: communism and the cold war -- Angelic pastor? Pius XII and the worldwide church -- The papacy in the Age of totalitarianism.