Emperor Julian the Apostate died while campaigning against the Persians in AD 363. He was wounded by spear thrown by an unknown hand on June 26th. There is some uncertainty about whether he died on that same night or whether he lingered. Modern scholarship, at least as represented by the relevant Wikipedia entry (yes, I know) suggests that he died on the third night after the wound, once an infection had set in. This would place his death on the night of 28th-29th June.
It is interesting in this regard to read a report which the 5th century Catholic historian Sozomen makes concerning Julian’s death. He writes:-
One of Julian’s friends had a divine vision, which I will now proceed to describe. He had, it is related, traveled into Persia, with the intention of joining the emperor. While on the road, he found himself so far from any habitation that he was obliged, on one night, to sleep in a church. He saw, during that night, either in a dream or a vision, all the apostles and prophets assembled together, and complaining of the injuries which the emperor had inflicted on the Church, and consulting concerning the best measures to be adopted. After much deliberation and embarrassment two individuals arose in the midst of the assembly, desired the others to be of good cheer, and left the company hastily, as if to deprive Julian of the imperial power.
He who was the spectator of this marvel did not attempt to pursue his journey, but awaited, in horrible suspense, the conclusion of this revelation. He laid himself down to sleep again, in the same place, and again, he saw the same assembly; the two individuals who had appeared to depart the preceding night to effect their purpose against Julian, suddenly returned and announced his death to the others.
The night of 28th-29th June was already at this period the vigil and the feast of Saints Peter and Paul. Was is it these two men whom the anonymous soldier and friend of Julian saw in his dream or vision as he lay on the floor of the sacred building? Would it not be fitting that these two apostles, who, as St Leo says, founded Rome far more happily that Romulus and Remus, should have been sent to deprive the Roman Emperor of the imperial power that he was so terribly abusing? That the two olive trees who stand before the Lord of all the earth should have brought low the lord seeking to remove the holy unction from Christendom?