June 28 is traditionally the feast day of Pope St Leo II, who died on this day in 683, after a reign of less than 11 months. The Liber Pontificalis, an important but not always reliable source of information about the early Popes, records that on the previous day he celebrated the ordination of nine priests, three deacons, and twenty-three bishops; it is not said that it was the ordination ceremony that killed him, but the heat of Rome in June and the inevitable length of such a ceremony make this seem likely more than coincidence. The principal achievement of his pontificate was the confirmation of the acts of the Sixth Ecumenical Council, the third of Constantinople, which condemned the Monothelite heresy; being fluent in Greek as well as Latin, he personally made the official Latin translation of the council’s acts. It is one of the oddities of hagiography that his predecessor St Agatho, in whose reign the council was held, and whose intervention (through his legates) in its deliberations was acclaimed with the words “Peter has spoken through Agatho!”, has never been honored with a general feast day in the West, but is kept on the Byzantine Calendar. Leo, on the other, was a Sicilian, and therefore born as a subject of the Byzantine Empire, but is not liturgically honored in the East.
(In this altar in St Peter’s Basilica are kept the relics of three Sainted Popes named Leo, the Second (682-3), the Third (795-816) and the Fourth (847-55). The altar of Pope St Leo I (440-61) is right next to it, and Pope Leo XII (1823-29) is buried in the floor between them.)
At Lyon, the ancient primatial see of Gaul, and in much of southern France, the day was kept as the feast of St Irenaeus, who was bishop of that city in the late 2nd century. In his book On Illustrious Men, St Jerome mentions the famous martyrdom in 177 of St Pothinus, Irenaeus’ predecessor in the see, but says nothing about the latter’s death, the date and circumstances of which are unknown; it is a rather later tradition that he died a martyr. It may very well be that his feast found its way to June 28th, the vigil of Ss Peter and Paul because of a famous passage in his book Against the Heresies (3.3.2) in which he attests to the primacy of the Roman See. The original Greek version of this book is lost, but it is preserved in a Latin translation, which is generally thought to have been made not long after its first publication.
“… maximae et antiquissimae et omnibus cognitae, a gloriosissimis duobus Apostolis Petro et Paulo Romae fundatae et constitutae Ecclesiae, eam quam habet ab Apostolis traditionem et annuntiatam hominibus fidem, per successiones Episcoporum pervenientem usque ad nos indicantes, confundimus (haereticos gnosticos)… Ad hanc enim Ecclesiam, propter potentiorem principalitatem, necesse est omnem convenire ecclesiam, hoc est, eos qui sunt undique fideles, in qua semper ab his qui sunt undique conservata est ea quae est ab Apostolis traditio.
We put to confusion (the Gnostic heretics) by indicating that tradition derived from the Apostles, of the very great, the very ancient, and universally known Church founded and organized at Rome by the two most glorious apostles, Peter and Paul; as also [by pointing out] the faith preached to men, which comes down to our time by means of the successions of the bishops. For it is a matter of necessity that every Church should agree with this Church, on account of its preeminent authority – that is, the faithful everywhere – inasmuch as the Apostolic Tradition has been preserved continuously by those who are everywhere.”
In 1921, Pope Benedict XV extended his feast to the general Calendar on his traditional Lyonese date, moving Pope Leo II to July 3rd, the next free day on the calendar, and the day of his burial according to the Liber Pontificalis.