Bede's Ecclesiastical History of England

CHAP. VIII. How, when the persecution ceased, the Church in Britain enjoyed peace till the
time of the Arian heresy. [325 AD]
When the storm of persecution ceased, the faithful Christians, who, during the time of danger,
had hidden themselves in woods and deserts and secret caves, came forth and rebuilt the churches
which had been levelled to the ground; founded, erected, and finished the cathedrals raised in honour
of the holy martyrs, and, as if displaying their conquering standards in all places, celebrated festivals
and performed their sacred rites with pure hearts and lips. This peace continued in the Christian
churches of Britain until the time of the Arian madness, which, having corrupted the whole world,
infected this island also, so far removed from the rest of the world, with the poison of its error; and
when once a way was opened across the sea for that plague, straightway all the taint of every heresy
fell upon the island, ever desirous to hear some new thing, and never holding firm to any sure belief.
At this time Constantius, who, whilst Diocletian was alive, governed Gaul and Spain, a man of
great clemency and urbanity, died in Britain. This man left his son Constantine [Constantine the
Great] born of Helena, his concubine, emperor of the Gauls. Eutropius writes that Constantine,
being created emperor in Britain, succeeded his father in the sovereignty. In his time the Arian
heresy broke out, and although it was exposed and condemned in the Council of Nicaea, nevertheless,
the deadly poison of its evil spread, as has been said, to the Churches in the islands, as well as to
those of the rest of the world.
CHAP. IX. How during the reign of Gratian, Maximus, being created Emperor in Britain,
returned into Gaul with a mighty army. [377 AD]
In the year of our Lord 377, Gratian, the fortieth from Augustus, held the empire for six years
after the death of Valens; though he had long before reigned with his uncle Valens, and his brother
Valentinian. Finding the condition of the commonwealth much impaired, and almost gone to ruin,
and impelled by the necessity of restoring it, he invested the Spaniard, Theodosius, with the purple
at Sirmium, and made him emperor of Thrace and the Eastern provinces. At that time, Maximus,
a man of energy and probity, and worthy of the title of Augustus, if he had not broken his oath of
allegiance, was made emperor by the army somewhat against his will, passed over into Gaul, and
there by treachery slew the Emperor Gratian, who in consternation at his sudden invasion, was
attempting to escape into Italy. His brother, the Emperor Valentinian, expelled from Italy, fled into
the East, where he was entertained by Theodosius with fatherly affection, and soon restored to the
empire, for Maximus the tyrant, being shut up in Aquileia, was there taken by them and put to
death.