On this day in 1559, Giovanni Angelo Medici was elected Pope, taking the name Pius, the fourth of that name. Among his many achievements can be numbered the final sessions (XVII-XXV) of the Council of Trent that took place from 1562 to 1563.
His other great achievement is the Profession of Faith of the Council of Trent or the Creed of Pope Pius IV, which, with the Apostles' Creed, the Nicene Creed and the Athanasian Creed, is one of the four Authorised Creeds of the Catholic Church.
It ends thus: "This true Catholic faith, outside of which no one can be saved, which I now freely profess and to which I truly adhere, I do so profess and swear to maintain inviolate and with firm constancy with the help of God until the last breath of life. And I shall strive, as far as possible, that this same faith shall be held, taught, and professed by all those over whom I have charge. I do so pledge, promise, and swear, so help me God and these Holy Gospels."
However, despite what we would consider to be towering achievements for the Catholic Faith, the gentleness of Pope Pius IV with which he treated the weak creatures who strayed from the path of the Faith, meant that his own orthodoxy was doubted by some in his own day. One fanatic, the wretched Benedetto Ascolti, even attempted to assassinate the Pope!
Of further interest is this venerable Pope's appointment to the post of Cardinal Nephew - by then the precursor of the Cardinal Secretary of State rather than the sinecure of a Pope's relation - his fellow Milanese, Saint Charles Borromeo. Pope Pius IV was succeeded by yet another Saint, Pope St. Pius V, after his death on 9th December, 1565.
All ye holy Pontiffs, pray for us!