Enea Silvio Piccolomini (1405-1464) had an extraordinary career, crowned with the papal tiara in 1458. As a secretary and later councillor and top diplomat of Emperor Friedrich III, he undertook many diplomatic missions. His reports on five of the most important ones have survived. The first mission was to Pope Eugenius IV in Rome in 1447, where he negotiated and presented the Holy Roman Empire's obedience to the Roman papacy and witnessed the pope's death and the election of his successor. The second, later in 1447, was to the city of Milan to make that city accept imperial rule after the death of the last Visconti duke. The third was to Bohemia in 1451, where he was to persuade the Bohemian estates to accept that the boy-king, Ladislaus the Posthumous, would remain under the emperor's guardianship until he came of age. Piccolomini also used the voyage to visit the Hussites in Tabor and have discussions with them, aiming at ending the Hussite schism. The fourth was to the imperial diet of Regensburg in 1454, summoned by the emperor to discuss a joint European military response to the Turkish conquest of Constantinople and the threat of a Turkish invasion of Europe. This report is also known as the History of the Diet of Regensburg. The fifth was to Pope Calixtus III in Rome 1455, where he presented the emperor's declaration of obedience and also prepared the way for his own appointment as cardinal, the last career step before he was elected pope in 1456. Piccolomini's five reports witness important political and religious processes in Europe at the middle of the fifteenth century and provide precious insight into the history of Renaissance diplomacy and the history of the Holy Roman Empire and the papacy.
