Constantinus I .—I. A. Ancient Authorities (Heathen).—Eutropius, Breviarium, Hist. Rom. , end of 9th and beginning of 10th book. This historian was secretary to the emperor, and his short account is therefore valuable. The Caesares and the Epitome , current under the name of Aurelius Victor, were doubtless the work of different authors. The first, who wrote under Constantius, was a friend of Ammianus, and praefectus urbi towards the close of the cent.; the second, who excerpted from the first, lived a generation later, and continued his compilation down to the death of Theodosius the Great. They seem to have used the same sources as Zosimus, whom they supplement. The Panegyrists, as contemporary writers, deserve more attention than has been given them, allowance being made for the defects incident to their style of writing. Those relating to our subject—Anon. Panegyr. Maximiano et Constantino (A.D. 307), Eumenii Constantino in natalibus urb. Trevir. (310), and Gratiarum actio Flaviensium nomine (311), Anon. de Victoria adv. Maxentium (313), and Nazarii Paneg. Constantino (321)—are all the product of Gallic rhetoricians. The Scriptores Hist. Augustae contain several contemporary references to Constantine; those in Julian's Caesars are, as might be expected, unfriendly and satirical. The first vol. of the Bonn ed. of the Byzantine historians contains the fragments of Eunapius, Priscus, Dexippus, etc., but these are of little moment, as are the extracts from Praxagoras in Photius, Cod. 62. Indirectly it is supposed that we have more of the matter of these earlier writers in Zosimus's ἱστορία νέα , bk. ii. This historian lived probably c. 450. He was a bitter enemy of Constantine, whom he accuses of various crimes and cruelties, and blames for the novelties of his policy, shewing a particular dislike of his conversion. He falls into several historical blunders. The part of Ammianus's Histories relating to this reign is unfortunately lost. Some remarks on it occur in the part preserved, from which we gather his general agreement with his friend and contemporary Victor. The text of Ammianus, pub. by Gardthausen (Teubner, 1874), may be recommended. He has also given a revised text from the MSS. of the anonymous excerpts generally cited as Anonymus Valesii, Excerpta Valesiana . They received this name from being first printed by H. Valois, at the end of his ed. of Ammianus. Some of these extracts may be traced word for word in Eutropius and Orosius; hence their author did not live earlier than the 5th cent. Others are valuable as coming from sources elsewhere unrepresented.

(Christian.) The earliest contemporary authority is Lactantius, de Mortibus Persecutorum , a tract pub. after the defeat of Maxentius and before Constantine had declared himself the enemy of Licinius—i.e. probably 313 or 314. His bitterness is unpleasant, and his language exaggerated and somewhat obscure, but his facts are generally confirmed by other authors, where we can test them. The most important is Eusebius. Three of his works especially treat of Constantine, Hist. Eccl. ix. and x., down to 324, and probably pub. before the death of Crispus in 326; de Vita Constantini , in four books, with a translation of Constantine's Oratio ad Sanctorum Coetum as an appendix, pub. after his death; and, thirdly, τριακονταετηρικὅς , or Laudes Constantini , a panegyric at his tricennalia, containing little but rhetoric. To harmonize Eusebius and Zosimus is difficult. Fleury's dictum, "on ne se trompera sur Constantin en croyant tout le mil qu’en dit Eusebe, et tout le bien qu’en dit Zosime," may be perfectly true, but Zosimus says very little good of him and Eusebius very little harm. Eusebius has great weight as a contemporary and as giving documents, which have not for the most part been seriously challenged; but he is discredited by fulsomeness and bad taste in his later works, and by inconsistencies of tone between them and his history. He announces, however, that he will only recount those actions of the emperor which belong to his religious life (V. C. i. 11: μόνα τὰ πρὸς τὸν θεοφιλῆ συντείνοντα βίον) , and is open to the criticism of Socrates (H. E. i. 1) as τῶν ἐπαίνων τοῦ βασίλευς καὶ τῆς πανηγυρικῆς ὑψηγορίας τῶν λόγων μᾶλλον ὡς ἐν ἐγκωμίῳ φροντίσας ἢ περὶ τοῦ ἀκριβῶς περιλαβεῖν τὰ γενόμενα . We must allow for the natural exultation of Christians over the emperor who had done so much for them and openly professed himself an instrument of Providence for the advancement of Christianity. Neither in the case of Eusebius nor of Zosimus must we push our distrust too far. The best ed. of the historical works of Eusebius is by F. A. Heinichen, repub. and enlarged (Leipz. 1868–1870, 3 vols.). The laws issued by Constantine (after 312) in the Theodosian and Justinian Codes are very important contemporary documents. The first are in a purer state, and may be consulted in the excellent ed. of Hanel (Bonn. 1842–1844), or in the older standard folios of Godefroi, with their valuable historical notes. Both codes are arranged chronologically in Migne's Patrologia, Opera Constantini , which also contains the Panegyrists and documents relating to the early history of the Donatists.

Socrates, H. E. i., and Sozomen, H. E. i. and ii. (about a cent. later), give an account of the last period of his reign; Socrates being generally the safer guide. On his relations with Arianism much is found in the treatises and epp. of St. Athanasius, and occasional facts may be gleaned from other Fathers. As a hero of Byzantine history and ἐσαπόστολος , Constantine has become clothed in a mist of fiction. Something may be gathered from Joannes Lydus, de Magistrat. P. R. , and among the fables of Cedrenus and Zonaras may be found some facts from more trustworthy sources.

B. Modern Authorities. —It will be unnecessary to enumerate the well-known writers of church history and the multitude of minor essays on separate points of Constantine's life. As early as 1720 Vogt (Hist. Lit. Const. Mag. Hamburg) gave a list of more than 150 authors, ancient and modern, and the number has since infinitely increased. The first critical life of importance is by J. C. F. Manso ( Leben Constantans des Grossen , Wien, 1819, etc.), but it is hard and one-sided, unchristian, if not antichristian. Jacob Burckhardt largely follows Manso, but is much more interesting and popular (Die Zeit Constantins des Gr. Basel, 1853), though not always fair. Some misstatements in it are noticed below. He views the emperor merely as a great politician, and shews much bitterness against Eusebius. Theodore Keim's Der Uebertritt Const. des Gr. (Zürich, 2863) is in many points a good refutation of Burckhardt, as well as being a fair statement from one not disposed to be credulous. The first two volumes of L’Eglise et l’Empire au IV e Siècle , by A. de Broglie (Paris, 1855, etc.), give the views of a learned Roman Catholic, generally based on original authorities, and this is perhaps the most useful book upon the subject. The section (134) in Dr. P. Schaff's Gesch. der Alten Kirche (Leipz. 1867, also trans.) is as good a short account of Constantine as can be named. In English we have a short life by a Nonconformist, Mr. Joseph Fletcher (Lond. 1852, 16mo), but no standard work of importance. The brilliant sketch by Dean Stanley in his Eastern Church is probably the fairest picture of Constantine in our language. For his relations with Arianism we may refer to Newman's Arians of the Fourth Cent. (1st ed. 1833; 3rd ed. 1871); Neale's Eastern Church, Patriarchate of Alexandria; Bright's History of the Church , A.D. 313–451, 2nd ed. 1869; and Gwatkin's Arian Controversy . A simple monograph on Constantine by E. L. Cutts is pub. by S.P.C.K.

II. Life.—Period i. To 312.—Flavius Valerius Aurelius Constantinus, surnamed Magnus or the Great, was born Feb. 27, probably in 274, at Naissus ( Nissa), in Dardania or Upper Moesia, where his family had for some time been settled. His father, Constantius Chlorus, was still young at the time of his son's birth. He was of a good family, being nephew by the mother's side of the emperor Claudius. A few years later we find him high in favour with Carus, who intended, it was said, to make him Caesar. Constantine's mother Helena, on the other hand, was of mean position, and apparently was married after her son's birth. Constantine was brought up at Drepanum in Cicilia, his mother's birthplace (Procop. de Aedif. Justin. v. 2). His father, on becoming Caesar and taking another wife, sent him, when about 16 years old, as a sort of hostage to Diocletian at Nicomedia, who treated him with kindness. His first military service was to accompany that emperor against Achillaeus in 296, and Eusebius saw him as a young and handsome man passing through Palestine into Egypt ( V. C. i, 19). In 297 he took part in the successful war of Galerius against the Persians; and about this time married Minervina. Constantine continued in the East while his father was fighting in Gaul and Britain. In 303 he was present when the edict of persecution against the Christians was promulgated at Nicomedia and the palace soon after struck by lightning. The concurrence of these two events made a strong impression upon him ( Orat. ad Sanct. Coet. 25). He also witnessed in 305 the abdication of the two Augusti, Diocletian and Maximian.

A higher destiny awaited him in another part of the empire. His father insisted upon his return, and Galerius at length was persuaded to give permission and the seal necessary for the public posts, ordering him not to start before receiving his last instructions on the morrow. Constantine took flight in the night. He had probably good reasons for his mistrust, and to stop pursuit maimed the public horses at many stations on his road (Zos. ii. 8; Anon. Val. 4; Victor, Caes. 21), which lay partly through countries where the persecution was raging. He arrived at Gesoriacum (Boulogne) just in time to accompany his father to Britain on his last expedition against the Picts (Eumen. in Nat. Urb. Trev. vii.). Constantius died at York, July 306, in the presence of his sons, after declaring Constantine his successor ( de M. P. xxiv.). He was almost immediately proclaimed Augustus by the soldiers ( Σεβαστὸς πρὸς τῶν στρατοπέδων ἀναγορευθείς , Eus. H. E. viii. 13). Almost at the same time another claimant of imperial power appeared at Rome in Maxentius, son of the retired Maximian, who now came forward again to assist his son. Constantine's first act was to shew favour to the Christians ( de M. P. xxiv.), who had been exposed to little of the violence of persecution under the mild rule of Constantius. ( V. C. i. 13–17. Eusebius seems here to exaggerate. Cf. Episcopor. partis Majorini preces ad Constantinum , in Op. Const. Migne, col. 747.) Constantine had at once to defend Gaul against the Franks and German tribes, who had risen during the absence of Constantius in Britain (Eumen. ib. , x.). In 307 Maximian, who had quarrelled with his son, crossed the Alps and allied himself with the Caesar of the West. Constantine received as wife his daughter Fausta, and with her the title of Augustus (Pan. Max. et Const. v.). For three years after marriage he found sufficient employment in consolidating his government in the West, and in wars upon the frontier of the Rhine, over which he began to build a bridge at Cologne. The seat of his court was Treves, which he embellished with many buildings, including several temples and basilicas, and the forum. Meanwhile Galerius was seized with a painful illness, and on April 30, 311, shortly before his death, issued his haughty edict of toleration, the first of the series, to which the names of Constantine and Licinius were also affixed. Constantine remained in the West engaged in wars with the Alemanni and Cherusci, and in restoring the cities of Gaul (cf. Eumen. Gratiarum actio Flaviensium Nomine , on the restoration of the schools of Autun). He is said to have interfered by letter on behalf of the Eastern Christians whom Maximinus Daza now began to molest, and this is in itself probable (de M. P. xxxvii.). We must remember that there were now four Augusti, Licinius and Maximinus in the East; Maxentius and Constantine in the West. The two latter had for some time acknowledged one another (see below, § VI. Coins ), and probably by tacit consent the four restricted themselves pretty nearly to the limits which afterwards bounded the four great prefectures. But there was little united action between them, and sole empire was perhaps the secret aim of each. Maxentius now felt himself strong enough to break with Constantine, and declared war against him. The latter determined to take the initative, and crossed the Cottian Alps, by the pass of Mont Genévre, with a force much smaller than that of his opponent. Later historians affirm that the Romans besought him by an embassy to free them from the tyrant (Zon. Ann. xiii.; Cedrenus, § 270), and this is probable, for Maxentius, by folly, insolence, and brutality had greatly alienated his subjects. Constantine had allied himself with one of the Eastern Augusti, Licinius, whom he engaged in marriage with his sister Constantia, but had to proceed against the counsels and wishes of his generals and the advice of the augurs ( Pan. de Vict. adv. Maxent. ii.). After taking Turin, he rested some days at Milan, where he was received in triumph, and gave audience to all who desired it ( ib. vii.). We may assume that at the same place and time, the spring or summer of 312, occurred also the betrothal of Constantia with Licinius, and the issue of a second edict of toleration to the Christians, that somewhat hard edict to which the emperors refer in the more celebrated announcement of 313 (see below § III. B. Religious Policy , and cf. Keim, Uebertritt , note 11). After taking Verona, Constantine apparently met with little resistance till within a few miles of Rome, though this is not quite consistent with the statement of Lactantius (de M. P. xliv.). He had turned the advanced guard of the enemy at Saxa Rubra, close to the Cremera, and then pressed forward along the Flaminian road to the walls of the city itself. With great rashness Maxentius had determined to give battle exactly in front of the Tiber, with the Milvian bridge behind him, about a mile from the gates of Rome. It was Oct. 26, and during the night, according to our earliest authority, Constantine was warned in a dream to draw the monogram of Christ, the