Taken from Volume II of Jameson’s Sacred and Legendary Art. Containing the Patron Saints, the Martyrs, the Early Bishops, the Hermits, and the Warrior Saints of Christendom, as represented in the Fine Arts. Riverside Press, 1896.
… the legend of Mercurius is extremely wild and striking. Julian the Apostate, who figures in these sacred romances not merely as a tyrant and persecutor, but as a terrible and potent necromancer who had sold himself to the devil, had put his officer Mercurius to death, because of his adhesion to the Christian faith. The story then relates that when Julian led his army against the Persians, and on the eve of the battle in which he perished, St. Basil the Great was favoured by a miraculous vision. He beheld a woman of resplendent beauty seated on a throne, and around her a great multitude of angels ; and she commanded one of them, saying, “Go forthwith, and awaken Mercurius, who sleepeth in the sepulchre, that he may slay Julian the Apostate, that proud blasphemer against me and against my son!” And when Basil awoke, he went to the tomb in which Mercurius had been laid not long before, with his armour and weapons by his side, and, to his great astonishment, he found neither the body nor the weapons. But on returning to the place the next day, and again looking into the tomb, he found there the body of Mercurius lying as before; but the lance was stained with blood; “for on the day of battle, when the wicked emperor was at the head of his army, an unknown warrior, bareheaded, and of a pale and ghastly countenance, was seen mounted on a white charger, which he spurred forward, and brandishing his lance, he pierced Julian through the body, and then vanished as suddenly as he had appeared. * And Julian being carried to his tent, he took a handful of the blood which flowed from his wound, and flung it into the air, exclaiming with his last breath, ‘Thou hast conquered, Galilean! thou hast conquered!’ Then the demons received his parting spirit. But Mercurius, having performed the behest of the blessed Virgin, re-entered his tomb, and laid himself down to sleep till the Day of Judgment.”
I found this romantic and picturesque legend among the Greek miniatures already so often alluded to, ** where the resurrection of the martyr, his apparition on the field of battle, and the death of Julian, who is falling from his horse, are represented with great spirit.
* Julian was killed by a javelin flung by an unknown hand. — Gibbon.
** Ninth Century. Paris Bib., Gr. MSS. 510.
Great-Martyr Saint Philopater Mercurius confound the enemies of Holy Church and triumph over all their designs. Amen.