The Ecclesiastical History of Sozomen

Meanwhile Gerontius, from being the most efficient of the generals of Constantine, became his enemy; and believing that Maximus, his intimate friend, was well qualified for the tyranny, he invested him with the imperial robe, and permitted him to reside in Tarracona. Gerontius then marched against Constantine, and took care to put Constans, the son of Constantine, to death at Vienna.

As soon as Constantine heard of the usurpation of Maximus, he sent one of his generals, named Edovicus, beyond the Rhine, to levy an army of Franks and Alemanni; and he sent his son Constans to guard Vienna and the neighboring towns. Gerontius then advanced upon Arles and laid siege to it; but directly, when the army of Honorius had come to hand against the tyrant, under the command of Constantius, the father of that Valentinian who subsequently became emperor of Rome, Gerontius retreated precipitately with a few soldiers; for the greater number of his troops deserted to the army of Constantius. The Spanish soldiery conceived an utter contempt for Gerontius, on account of his retreat, and took counsel how to slay him. They gathered in close ranks and attacked his house at night; but he, with one Alanus, his friend, and a few servants, ascended to the top of the house, and did such execution with their arrows that no less than three hundred of the soldiers fell. When the stock of arrows was exhausted, the servants made their escape by letting themselves down secretly from the building; and Gerontius, although he might have been saved in a similar fashion, did not choose to do so, because he was restrained by his affection for Nonnichia, his wife. At daybreak of the next day, the soldiers cast fire into the house; when he saw that there was no hope of safety left, he cut off the head of his companion, Alanus, in compliance with his wish. After this, his own wife was lamenting, and with tears was pressing herself with the sword, pleading to die by the hand of her husband before she should be subjected to others, and was supplicating for this last gift from him. And this woman by her courage showed herself worthy of her religion, for she was a Christian, and she died thus mercifully; she handed down to time a record of herself, too strong for oblivion. Gerontius then struck himself thrice with his sword; but perceiving that he had not received a mortal wound, he drew forth his poniard, which he wore at his side, and plunged it into his heart.