'The Holy See and the Wandering of the Nations, from St. Leo I to St. Gregory I' is a book that tells the history of the world's nations through the letters sent out by the Pope elected at the time. It covers the period between Pope Leo I, best known for having met Attila the Hun in 452 and persuading him to turn back from his invasion of Italy, all the way up to the reign of Pope Gregory I, remembered today for instigating the first recorded large-scale mission from Rome, the Gregorian Mission, to convert the then largely pagan Anglo-Saxons to Christianity.