In 1964, Pope Paul VI ordered the Vatican diplomatic archives covering the period of World War II opened, and they were eventually published in 12 volumes. Blet taught history at the Pontificia Academia Ecclesiastica for 17 years, and here constructs from those records an account of what is widely perceived as Pius XII's silence at the time about the Nazi treatment of Jews. He concludes that Pius did much more privately than publicly to protect Jews and others threatened. It was first published as Pie XII et la Secunde Guerre Mondiale by Academique Perrin in 1997.