The Life of Constantine remains the most important work for the life of the emperor, who ruled between 306 and 337 and as sole emperor from 324-337 CE. The manuscripts attribute the work to the church historian Eusebius of Caesarea, who died two years after Constantine (over the years there has been debate about the work’s authorship, but it is now widely accepted to be Eusebius; see Timothy Barnes, “Panegyric, History, and Hagiography,” p. 114-115). There have been questions regarding the work’s authenticity in the past, largely due to the overwhelmingly Christian presentation of the emperor (see, for instance, “Eusebian Frauds in the Vita Constantini”), and it has been argued that Eusebian material was added after the author’s death, during the reign of Constantius II, owing to the substantial reuse of material from Eusebius’s previous writings, largely the Ecclesiastical History. However, it is likely that Eusebius simply draws on his earlier work in order to refashion his material to suit his current apologetic purpose (on the employment of the Ecclesiastical History in the Life of Constantine, see Stuart G. Hall, “The Use of Earlier Eusebian Material”; Cameron and Hall, in their commentary on the text, are happy to accept Eusebian authorship; for a discussion, see Life of Constantine, p. 4-9). The first two books of the work draw upon Eusebius’s earlier narrative in the Ecclesiastical History, but in a decidedly more apologetic tone. The author then begins at the point at which he left off, offering a detailed description of the campaign against Licinius, and continuing up until Constantine’s death. It seems, however, that Eusebius died before completing the work. The emperor attended the Council of Nicaea in 325 CE, and this may well have been one of the only times that Eusebius actually came directly into contact with him; certainly, he did not have a personal relationship with Constantine. Essentially a panegyrical work, the text strongly asserts the role of Christianity in the emperor’s rise to power and success, and it seems that one of its purposes was to try and ensure that Constantine’s sons, declared Augusti in 337 CE, would continue their father’s pro-Christian policies (Cameron and Hall, The Life of Constantine, p. 3).

This passage asserts Constantine’s superiority to his predecessors, and draws comparisons with Alexander the Great (the Macedonian) to emphasise his achievements as a ruler, particularly in terms of expansion of the empire and the submission of foreign rulers to Rome. After having first recalled that Constantine started his reign at the age at which Alexander died and that his reign lasted twice as long as that of Alexander, Eusebius praises Constantine for having succeeded to establish a world-wide dominion. A parallel with Alexander’s empire is implicit when Eusebius enumerates, through a combination of topoi (notably the mention of the Scythians and the Ethiopians, which go back at least to Herodotus; see particularly Herodotus, Histories book IV; for Herodotus’s representation of these peoples, see Hartog, The Mirror of Herodotus, esp. p. 19-33, 44, 166, 176-177) and of actual contemporary military campaigns (such as those in Britain and Egypt, against the Blemmyans), that Constantine succeeded to submit peoples from the far West, North, and South. Then, the comparison becomes explicit when Eusebius deals with the conquests in the far East. As Constantine did not of course travel as far as Alexander towards the East, Eusebius argues that Constantine diffuses “the effulgence of his holy light to the ends of the whole world, even to the most distant Indians.” This is an assessment which is of course far-fetched, but which shows how it was important for Eusebius to find correspondences between every aspect of Alexander and Constantine’s policies.

Eusebius narrates that the emperor succeeded his father, Constantius Chlorus (on the 25^th of June, 306 CE, at the age at which Alexander died. Moreover, he lived twice as long as Alexander, and trebled the territory that he inherited when he ascended to the throne. Highly significant is the language used to describe the way in which the emperor commanded his troops: “mild (ἥμερος, hēmeros) and sober (σώφρων, sōphrōn),” with “godliness” (θεοσέβεια, theosebeia). As Cameron and Hall recognise, this language evokes that of the classic imperial virtues, clementia and prudentia in Latin (Life of Constantine, p. 189; they also reference on this issue C. E.V. Nixon and Barbara Saylor Rodgers, Panegyrici Latini, p. 22). However, Constantine’s piety (exemplified through his “godliness”) is particularly important to Eusebius, who wishes to present the emperor as the archetypal Christian ruler, whose pious nature affects every facet of his rule, including significantly his command of the army. The connection between Constantine’s Christianity and his role as head of the Roman army is illustrated by Eusebius’s description of how, following his victory in 312 CE over Maxentius at the Milvian Bridge, he instructed his armies to carry standards depicting the Chi Rho (Christ’s initials), as a reminder of the divine protection of the army (see the discussion in the commentary on the Colossus of Constantine). In this phrase, therefore, we see the Christianising of classic imperial attributes, with the traditional piety expected of Roman emperors specifically directed towards the Supreme Deity. 

Eusebius goes on to list Constantine’s campaigns, exemplifying his world-wide dominion (this theme appears again in book IV, with the specific peoples mentioned here at chapters 5-7, 50). For Timothy Barnes, Eusebius understands Constantine’s dominion of earth as a replica of Christ’s heavenly kingdom, with the emperor representing the “ideal monarchy which exists in the celestial realm.” As Barnes acknowledges, the notion of the monarchy reflecting divine kingship was already held in Hellenistic culture, but Eusebius distinctly Christianises it through Constantine (Constantine and Eusebius, p. 253-254, quotation at p. 254). Interestingly, in II.1-2, Eusebius states that he will not discuss in his biography Constantine’s war activities, choosing instead to focus on his religious achievements. The present passage seems to contradict this claim, however, Eusebius makes sure to emphasise that these conquests enabled the emperor to spread “his holy light” and proclaim God’s name. Constantine’s actions are not purely expansionist ambition, then, at least not as Eusebius would have us believe; they are framed as a sacred duty to take the message of God to the farthest extremes of the oikoumenè.

That Constantine is described as being “acknowledged and celebrated by all” attests to his universal dominion (Cameron and Hall, Life of Constantine, p. 189). Earlier writers had discussed Christianity in relation to Rome’s expansion in terms of how Christianity benefitted the empire despite being persecuted, due to the prayers of Christians obeying biblical commands to obey the authorities sanctioned by God (see Romans 13:1-7; 1 Clement 60:4-61:3), or viewed the empire as a means for the spreading of the Gospel due to its encompassing of all nations and languages (see, for instance, the third-century Commentary on Daniel IV.9). However, in the present text, through Constantine we see the far-reaching dominion of Rome, one of its defining characteristics, utilised for the spreading of God’s word in a positively conscious sense. Rather than Rome being used as a somewhat hostile agent by God, the empire’s head is now actively furthering the dissemination of ‘true religion’ by means of his conquests.