Praxagoras of Athens,
History of Constantine the Great (330s)

Read the History of Constantine the Great by Praxagoras of Athens,1 in two books. In this he tells us that Constantine’s father, Constantius, was governor of Britain and Spain; Maximin2 of Rome, the rest of Italy, and Sicily; the other Maximin 3 of Greece, Asia Minor, and Thrace; Diocletian, as the eldest, governed Bithynia, Arabia, Lybia, and that part of Egypt that is watered by the Nile. Constantine was sent by his father to Diocletian in Nicomedia to be educated. At that time Maximin,4 governor of Asia Minor, who happened to be there, determined to lay a plot against the youth and set him to fight with a savage lion. But Constantine overcame and slew the beast, and having discovered the plot, took refuge with his father, after whose death he succeeded to the throne.

Soon after his accession, he subdued the Celts and Germans, neighbouring and barbarous nations. Having learnt that Maxentius, who had made himself master of Rome after Maximin,5 treated his subjects with cruelty and brutality, he marched against him, to punish him for his conduct. He was speedily victorious and put his enemy to flight, who fell into the pit which he had prepared for others and met the death which he had designed for his enemies. The Romans cut off his head, hung it on a spear, and carried it through the city. This part of the empire with joyful eagerness submitted to Constantine.

In the meantime, Maximin (who had plotted against Constantine) had died and was succeeded in his government by Licinius. Constantine, hearing that he also treated his subjects with cruelty and inhumanity, unable to tolerate such brutality towards those of the same race, marched against him, to put an end to his tyranny and replace it by constitutional government. Licinius, being informed of the expedition, became alarmed, attempted to disguise his cruelty under the cloak of humanity, and took an oath that he would treat his subjects kindly and would strictly keep his promise. Constantine accordingly for the time abandoned his expedition. Soon afterwards, however, since the wicked cannot remain quiet, Licinius broke his oath and abandoned himself to every kind of villainy. Whereupon Constantine attacked and defeated him in several great battles and shut him up and besieged him in Nicomedia, whence he approached Constantine in the garb of a suppliant. His kingdom was, taken away from him and bestowed upon Constantine, who thus secured and became sole ruler of the different parts of the great empire, which had long desired an emperor worthy of it. He inherited his father’s kingdom and that of Rome after the overthrow of Maximin,6 and obtained possession of Greece, Macedonia, and Asia Minor by the deposition of Licinius. He further assumed control of that part which had belonged to Diocletian, and had been held by Licinius, who had  seized it by right of war from Maximin,7 Diocletian’s successor.

Being thus sole master of a united empire, he founded Byzantium and called it after his own name. Praxagoras says that although Constantine was a heathen, in virtue, goodness, and prosperity he far excelled all his predecessors on the throne. With these words the history concludes.

Sozomen (around 440)

https://www.newadvent.org/fathers/2602.htm

Socrates (around 440)

https://www.newadvent.org/fathers/2601.htm

Theodoret (around 440)

https://www.newadvent.org/fathers/2702.htm

Athenasius 

But knowing at the same time that Constantine of worthy memory had with all accuracy and deliberation published the Faith then drawn up; when he had been baptized by the hands of men, and had departed to the place which was his due, [we think it] unseemly to make a subsequent innovation and to despise so many saints, confessors, martyrs, who compiled and drew up this decree;

(After Nicaea before death. source dates to 360s)

Philostorgius (433)

Does not mention baptism.

Epitome de Caesaribus

(Says bridge of boats was above(upstream) of milvian bridge)

(1st description of Crispus’s death)

https://topostext.org/work/745

395-408

Eutropius (Breviarium)

(Nothing of note) 

https://www.tertullian.org/fathers/eutropius_breviarium_2_text.htm

 Festus (Breviarium)

(Nothing of note)

https://www.attalus.org/translate/festus.html

Liber pontificus 

https://ia801907.us.archive.org/8/items/LiberPontificalis/Liber%20pontificalis.pdf