Ancient accounts of the Battle of the Milvian Bridge in 312 are numerous and contradictory.Footnote ¹ Wary of those who seek to reconstruct the course of the conflict, Raymond Van Dam cautions against trying to ‘conflate the ancient accounts into a single master narrative’; rather, attention to ‘differences in detail’ may shed light on their ‘authors’ differing agendas’.Footnote ² This article focusses on one such distinctive detail. Ancient authors agree that Maxentius drowned while trying to cross the Tiber, though the particular conditions of his demise vary from text to text. A panegyric in honour of Constantine delivered in 313, for example, claims that Maxentius, on horseback, perished as he was fording the river in retreat. Lactantius, writing a year or two later, says that Maxentius tried to flee across the Milvian Bridge, but so many of his terrified troops were crammed into the span that he was pushed into the Tiber.Footnote ³ Among those writing soon after the battle, Eusebius alone says that Maxentius died whilst crossing the river on a bridge built of boats.Footnote ⁴ This detail, I argue, suggests that Maxentius may be seen as a latter-day Xerxes, the Persian emperor who, in preparation for his invasion of Greece in 480 b.c., famously spanned the Hellespont with a pair of boat-bridges, enabling his army to march from Asia to Europe. I will first review the seminal accounts of Xerxes’ feat in Aeschylus’ Persians and Herodotus’ Histories, and then discuss the story's continuing currency in Eusebius’ time. Next I will suggest that the vocabulary in Eusebius’ accounts of the battle echoes the distinctive language used by Aeschylus, Herodotus and later authors to describe Xerxes’ achievement. In conclusion, I will consider how the parallel between Xerxes and Maxentius contributes to the latter's characterization as a tyrant.

In Aeschylus’ Persians (472 b.c.), the failure of Xerxes’ campaign is revealed to the Persian court. The bridging of the Hellespont is central to the play. It is first mentioned by the chorus, who liken it to ‘casting a yoke about the neck of the sea’.Footnote ⁵ The language of yoking—ζευγνύναι, ζυγόν and cognates—has long been recognized as the play's ‘dominant metaphor’.Footnote ⁶ Later the Persian queen says that her son Xerxes ‘by craft yoked the strait of Helle to make a pathway’ over the sea.Footnote ⁷ ‘By craft’ renders μηχαναῖς, which indicates a cunning contrivance, an innovative use of technology; μηχανή appears twice in the play, both times in reference to Xerxes’ bridge.Footnote ⁸ Through a marvel of engineering, the Persian king turns sea into land, links distinct continents; this transgression of natural limits ordained by the gods invites their displeasure. In the Persians, yoke-imagery may also connote political and social domination, that of a tyrant over his subjects, a master over his slaves. According to the chorus, the purpose of Xerxes’ expedition is ‘to cast a yoke of slavery about Greece’.Footnote ⁹ Military conquest and the conquest of nature are conjoined: for Xerxes to subjugate Greece, he must first subjugate the Hellespont.Footnote ¹⁰

Herodotus makes the crossing of the Hellespont central to Xerxes’ campaign and characterization. It caps a series of water-crossings by Xerxes and his imperial predecessors; these crossings, often made on custom-built bridges, constitute ‘a significant motif in Herodotus’, used ‘to prove the hybris of the aggressor’.Footnote ¹¹ In reference to them, Herodotus, like Aeschylus, draws on the vocabulary of yoking. Of thirty instances of ζευγνύναι in the Histories, twenty-six are associated with Persian conquest.Footnote ¹² When Xerxes informs Persian nobles of his plan to invade Greece, he says: ‘I intend, after yoking the Hellespont (ζεύξας τὸν Ἑλλήσποντον), to lead an army through Europe against Greece, that I may punish the Athenians’ (7.8.β). As we will see, the participle ζεύξας becomes especially emblematic of Xerxes’ accomplishment. Xerxes goes on to vaunt that not just Greece but all Europe will come to bear ‘the yoke of slavery’ (δούλιον ζυγόν).Footnote ¹³ Also associated in Herodotus with Xerxes and the other Persian monarchs is the verb διαβαίνειν, which indicates a boundary-crossing undertaken for the purpose of conquest; when a river is crossed without hostile intent, Herodotus prefers περᾶν.Footnote ¹⁴ Like ζευγνύναι, διαβαίνειν links geographical transgression and imperialistic aggression. διαβαίνειν appears more often in Book 7, in which Herodotus dilates on the Persians’ bridging of and march across the Hellespont, than in any of the other eight books of the Histories. Footnote ¹⁵ The cognate noun διάβασις appears seven times in Herodotus, six of which refer to an ultimately disastrous Persian campaign facilitated by a boat-bridge; half of the six refer to Xerxes’ spanning of the strait: ‘After the crossing of the Hellespont (ἀπὸ δὲ τῆς διαβάσιος τοῦ Ἑλλησπόντου), where the barbarians began their march, having passed a month there whilst they were crossing (διέβαινον) into Europe … they captured the city [of Athens], deserted’ (8.51). For Herodotus as for Aeschylus, Xerxes’ constructions at the Hellespont, described in distinctive language, reified his overweening ambition and thirst for domination.

Throughout antiquity, Xerxes remained a familiar figure, found in a host of Greek and Latin texts. As early as the fourth century b.c., the psychologically complex and not wholly unsympathetic Xerxes of Aeschylus and Herodotus was in most texts replaced by Xerxes the quintessential barbarian tyrant, remembered for a few notorious acts, among them his bridging of the Hellespont, which is mentioned by dozens of ancient authors.Footnote ¹⁶ This particular act became a trope; a cautionary tale of despotic, self-destructive excess; a ‘shorthand for the arrogance and transgressive behaviour of the king’.Footnote ¹⁷ Numerous later writers used the distinctive language of Aeschylus and Herodotus, especially ζευγνύναι, διαβαίνειν and their cognates, in reference to it.Footnote ¹⁸

Although Eusebius mentions Xerxes’ crossing of the Hellespont only once and briefly,Footnote ¹⁹ he will have been familiar with the monarch's memorable deeds at the narrows. For Eusebius seems to have read at least some of Herodotus’ Histories, and certainly had a thoroughgoing knowledge of other writers who treated Xerxes’ feat, including Diodorus Siculus, Philo, Josephus and Clement of Alexandria.Footnote ²⁰ Eusebius encountered ethnographical descriptions of the Persians as a people: his own view of them is far from positive, for he charges them—at least those who have not converted to Christianity—with engaging in incestuous marriages and incubating the insidious prophet Mani.Footnote ²¹ He knows Persian history, including Xerxes’ invasion of Greece.Footnote ²² Moreover, the Persian Wars generally and the bridging of the Hellespont specifically were, for centuries, common themes in both Greek and Latin declamations, so much so that Lucian, in the second century, satirized rhetors of his day for turning too often to these hoary, hackneyed subjects.Footnote ²³ References to Xerxes at the Hellespont were still frequent in Greek (and Latin) orations and rhetorical treatises dating to the fourth century. Given Eusebius’ knowledge of the Greek historiographical and rhetorical traditions, he must have repeatedly encountered Xerxes’ famed act.

One final point should be made about that act before we turn to Eusebius’ accounts of the Battle of the Milvian Bridge. Although Xerxes’ boat-bridges came to be viewed symbolically, as representations of his character, they were also logistically practical and technologically ingenious. Boat-bridges were later employed by generals with sophisticated engineers at their disposal, including Roman emperors on campaign. Not every bridge of boats erected in antiquity, then, should necessarily be considered an avatar of its builder's hubris. But the building of such a bridge does invite comparison with Xerxes’, as the first and most famed example thereof. When a boat-bridge is built by a figure such as Maxentius, who, as we will see, is by Eusebius repeatedly branded a tyrant and, moreover, compared to the Pharaoh of Exodus, the Eastern barbarian despot who enslaved a foreign people resident in his land, an ancient reader is primed to view that span in the light of the Hellespontine boat-bridges of Xerxes, another Eastern barbarian despot who enslaved his subjects.

With Xerxes’ boat-bridges in mind, and the distinctive vocabulary used to describe them, we now turn to Eusebius’ two accounts of the Battle of the Milvian Bridge on 28 October 312. His first account appears in the ninth book of the Ecclesiastical History, a work that most scholars believe to have been revised by Eusebius more than once, the last major update taking place after the death of Emperor Licinius on 19 September 324, probably in 325 or 326. His narrative of the battle, drawing on a lost source, was composed soon after it, probably within a year and no later than 315.Footnote ²⁴ The second account appears in Book 1 of his Life of Constantine, a work that reached its final form after the death of Constantine on 22 May 337 and before Eusebius’ own death on 30 May 339. On the whole, this later text portrays Maxentius as an even more villainous and tyrannical figure, but its account of the battle itself mostly follows the earlier one, at points reproducing it verbatim.Footnote ²⁵

To ready the reader for Constantine's march on Rome, Eusebius describes a lurid litany of acts—murder, plunder, rape, necromancy—committed by Maxentius, which testify to his ‘fearsome tyranny’ (δεινῇ … τυραννίδι) and the ‘bitter slavery’ (πικρὰν … δουλείαν) he imposed on the residents of the former capital.Footnote ²⁶ These acts, characteristic of the stereotypical ancient tyrant,Footnote ²⁷ manifest Maxentius’ cruelty, greed, impiety and unrestrained appetite for sex and violence, and thus serve to justify the invasion of Italy by Constantine, its liberator. As the story of the battle begins, Constantine is ‘very near’ (ἄγχιστα) Rome, whereas Maxentius remains within the city's walls, relying less on his people's loyalty than on the devices of sorcery (ταῖς κατὰ γοητείαν μηχαναῖς) for his defence (Hist. eccl. 9.9.3 ~ Vit. Const. 1.37.2–1.38.1). Like Aeschylus’ Xerxes, he employs artificial contrivances (μηχαναί), in this case of a supernatural sort. Although ensconced in Rome, Maxentius is forced to fight, for ‘God himself, as if by chains, drags the tyrant far beyond the gates’ and across the Tiber (Hist. eccl. 9.9.4 ~ Vit. Const. 1.38.1). Like a fettered captive, Maxentius is extracted from the city: the despot who has enslaved his subjects is himself enslaved by God. Then follows an elaborate typological comparison between the battle and the Israelites’ crossing of the Red Sea. Oscillating between scriptural quotation and battle narrative, Eusebius melds the two events (Hist. eccl. 9.9.5 ~ Vit. Const. 1.38.2):

Immediately after this passage Eusebius rewinds to explain how Maxentius and his men found themselves submerged. Through a string of aorist participles, Eusebius takes us back to the construction of Maxentius’ boat-bridge (Hist. eccl. 9.9.5 ~ Vit. Const. 1.38.2):

Eusebius’ language here recalls Xerxes at the Hellespont. Maxentius bridged the ‘river’ (ποταμός) with boats; Xerxes bridged the strait—which the king calls a ‘river’ (ποταμός) in Herodotus (7.35)—by the same. To describe Maxentius’ construction, Eusebius, fond of pleonastic doubling, employs not only γεφυροῦν, ‘to span’, which may be used of a broad range of structures, including dams, viaducts and all manner of bridges, but also ζευγνύναι, ‘to yoke’, which refers specifically to boat-bridges and, as we have seen, has long been associated with Xerxes’ spanning of the Hellespont.Footnote ²⁸ Even more tellingly, the verb appears in the participial form ζεύξας, the form used to describe Xerxes’ bridging of the Hellespont by nine authors spanning seven centuries; indeed, of all the form's appearances in Greek literature that predate Eusebius, nearly one-quarter have Xerxes as their subject.Footnote ²⁹ Moreover, Maxentius’ construction is called a μηχανή, a mechanism, a contrivance. As noted, the word appears twice in Aeschylus’ Persians, both times in reference to Xerxes’ bridge.

Following this passage Eusebius’ two accounts of the battle briefly diverge. The later version in the Life of Constantine (1.38.3), expanding on the μηχανή just mentioned, explains that Maxentius hid ‘secret mechanisms’ (κρυφίους μηχανάς) within the boat-bridge so that it would plunge Constantine into the river as he was crossing it in pursuit; such details are absent from the earlier version. The dissolution of the bridge under Maxentius is then narrated. The earlier version in the Ecclesiastical History says ‘when the boat-bridge over the river was destroyed’, whereas the later version in the Life of Constantine, the text of which requires supplementation, reads ‘when the boat-bridge's mechanisms and the trap within them <was destroyed> at an unanticipated time’.Footnote ³⁰ In both versions, the bridge is called a ζεῦγμα, a word cognate with ζευγνύναι and frequently used in reference to Xerxes’ spans across the Hellespont.Footnote ³¹ In the earlier version, the word is modified by διαλυθέντος, from διαλύειν, ‘to destroy’, a verb used to describe the destruction of Xerxes’ Hellespontine bridges three times by Herodotus and by subsequent authors as well.Footnote ³² The same word may also have been used in the later version—indeed, some editors of the Life of Constantine have inserted it as a supplement—but this suggestion must be considered tentative because of the textual trouble just mentioned. In any case, Eusebius’ two accounts thereafter run parallel once again: ‘the crossing sinks, and in a moment the boats drop into the deep, men and all.’Footnote ³³ As already noted, διάβασις used here is strongly associated in Herodotus and later authors with ill-starred Persian campaigns that relied on boat-bridges, especially Xerxes’ transit of the Hellespont. In Eusebius, the same noun flags another failed military venture, that of Maxentius, here presented as Xerxes’ avatar.

Before we turn to the significance of this Xerxes–Maxentius connection, an important if insoluble question ought to be addressed: should this linking of the leaders be credited to Eusebius or to his source(s) for the battle? Scholars have posited for decades that Eusebius drew on a source or sources, now lost, for his accounts of Constantine's campaign in Italy. In 2019, Van Dam convincingly argued that Eusebius employed a single source, a pagan panegyric composed in Latin, to which he added his own Christianizing gloss, including the comparison of the battle and the crossing of the Red Sea.Footnote ³⁴ He demonstrated that Eusebius’ accounts include just the sort of content commonly found in panegyrics and recommended for inclusion in them by rhetorical theoreticians.Footnote ³⁵ In his guidelines for speeches on rulers (βασιλικοὶ λόγοι), for example, Menander Rhetor recommends that those discussed in such orations be frequently compared with prominent persons of the past (2.1.13, 15, 18, 36). The oratorical exercises (προγυμνάσματα) attributed to Hermogenes put it succinctly: ‘in encomiums, the best source of argument is comparison’ (7). Comparisons are indeed rife in extant panegyrics, and Xerxes is a not uncommon comparand.Footnote ³⁶ So it seems possible, if not provable, that Eusebius encountered a comparison between Xerxes and Maxentius in his source. Since that source was written in Latin, however, Eusebius must have been responsible for using in his battle narratives the marked Greek vocabulary linked to Xerxes’ actions at the Hellespont.

This identification of Maxentius with Xerxes adds another dimension to Maxentius’ representation as a tyrant, in Eusebius and other contemporary sources. The semantic range of the term ‘tyrant’ (Latin tyrannus/Greek τύραννος) broadened in the fourth century: it continued to denote an oppressive, morally depraved autocrat, but also accumulated new associations.Footnote ³⁷ First, it could connote a usurper, someone whose claim to imperial power was rejected by his rivals. Second, it could connote a persecutor of God's people. In Greek, the word is attested in the latter sense as early as 4 Maccabees and the works of Clement of Alexandria and Origen, in which monarchs who oppressed Jews were branded τύραννοι. In Latin, ‘tyrant’ with this connotation, used as early as Tertullian, was popularized by Lactantius: in his On the Deaths of the Persecutors (c.315), many emperors who persecute Christians are called tyranni.Footnote ³⁸ In the fourth century, then, ‘tyrant’ could mean not just despot but also pretender and persecutor.

Maxentius was the ‘prototype of the late antique tyrant’.Footnote ³⁹ His defeat at the Milvian Bridge was essential to the victor's early image: Lenski has argued that, from soon after the battle through 321, Constantine's predominant mode of self-presentation was as a tyrannicide.Footnote ⁴⁰ Just months after his rival's defeat, Constantine refers to Maxentius as a tyrant in two laws dating to January 313; he does so again in a letter from spring 313 and in a law dating to 19 March 314.Footnote ⁴¹ Panegyrics declaimed in 313 and on 1 March 321 present Maxentius in tyrannical terms; the later speech refers to him as tyrannus ‘more than any other single noun or adjective’.Footnote ⁴² The most conspicuous characterization of Maxentius as tyrant is found on the famed arch in Rome dedicated to Constantine when he was visiting the city between July and September 315. There, on a prominently placed monument that portrays the Battle of the Milvian Bridge, twin inscriptions proclaim, in language reminiscent of Augustus’ Res Gestae, that Constantine ‘avenged the Republic with just arms’ by freeing it ‘from both the tyrant and his entire faction’.Footnote ⁴³ Although the inscriptions make clear that the Senate and the People of Rome dedicated the arch, whether the Senate or the emperor was primarily responsible for its design is disputed.Footnote ⁴⁴ Yet both parties surely would have approved of the inscriptions’ anti-tyrannical message. As we have seen, in Eusebius, too, Maxentius is repeatedly represented as a tyrant. In narrating Constantine's campaign against him in the Life of Constantine, for example, the author uses τύραννος or its cognates of Maxentius sixteen times in just fifteen sections (1.26–41). But Eusebius is distinctive in that he assimilates Maxentius to that ‘impious tyrant of old’, Pharaoh, who had oppressed the Israelites in Egypt.Footnote ⁴⁵

What has perhaps not been fully appreciated about Eusebius’ comparison of Maxentius and Pharaoh, which has received far less attention than his corollary comparison of Constantine and Moses,Footnote ⁴⁶ is that it exemplifies a familiar stratagem in Roman political propaganda, one in which a native rival is recast as an Eastern enemy, turning internecine infighting into foreign conquest.Footnote ⁴⁷ The most familiar example of this is Octavian's portrayal of Mark Antony. Barnes thus rightly draws an illustrative parallel between Maxentius’ defeat at the Milvian Bridge and Antony's at Actium.Footnote ⁴⁸ The comparison with Pharaoh reconfigures Maxentius—who had promoted himself as a pro-senatorial princeps, a booster and benefactor of the ancient capital, a reactionary alternative to the distant authoritarian tetrarchsFootnote ⁴⁹—as a foreign ‘enemy within’, an Eastern despot resident in Rome.Footnote ⁵⁰ Presenting Maxentius as a new Xerxes reinforces this characterization, but also reflects another long-standing practice, one attested in Rome as early as the first century b.c., in which the Persian Wars are mapped onto contemporary events.Footnote ⁵¹ Campaigns undertaken on the eastern frontier, especially those against the Parthian kings of Persia (who claimed descent from Xerxes’ family), by Augustus, Lucius Verus, Caracalla and Gordian III are variously presented, in literary sources and artistic representations, as revivals of the Persian Wars.Footnote ⁵²

Xerxes was a familiar figure in these Roman re-imaginings. According to Plutarch and other authors, the Late Republican general L. Licinius Lucullus, a lover of luxury, was branded Xerxes togatus, ‘Xerxes in a toga’, because of, among other things, the enormous opulent structures he erected over the sea, which, in their scale, grandiosity and blurring of natural boundaries, recalled the bridging of the Hellespont.Footnote ⁵³ The poet Lucan likens his anti-hero Julius Caesar to Xerxes when the Roman general builds a massive mole by chaining tree-trunks together to blockade the harbour of Brundisium.Footnote ⁵⁴ In 39, Caligula had a boat-bridge erected across the waters between Baiae and Puteoli in the Bay of Naples that he traversed on two consecutive days in a sort of quasi-triumph. Suetonius reports that many thought the emperor built the bridge to rival Xerxes’, and Cassius Dio has Caligula, using the Xerxean form ζεύξας, boast that his bridge was longer than the Persian king's.Footnote ⁵⁵ Evocations of Xerxes continue to appear in literary works of the later empire. In 310, a panegyrist praises Constantine's construction of a permanent span across the Rhine at Cologne, contrasting it with both Xerxes’ and Caligula's temporary boat-bridges.Footnote ⁵⁶ The historian Zosimus’ account of Constantine's victory over Licinius at the Hellespont in 324, drawing on a lost source, evokes the Greeks’ triumph over the Persians at Salamis in 480 b.c. and thereby presents another defeated rival of Constantine as Xerxes rediuiuus.Footnote ⁵⁷

Eusebius’ portrayal of Maxentius as Xerxes, then, is another example of how prominent Romans might be unfavourably likened to the Persian emperor, remembered for centuries as the ‘archetypal barbarian oppressor’.Footnote ⁵⁸ This portrayal may also take part in the venerable practice, described above, of linking Roman campaigns on the eastern frontier to the Persian Wars. For in the latter part of his reign Constantine intended to invade Persia, then ruled by the Sassanid dynasty; indeed, some sources say that he died during the early stages of his expedition, en route to the east from Constantinople.Footnote ⁵⁹ Eusebius was aware of his intention: he describes Constantine's preparations for the invasion.Footnote ⁶⁰ When Constantine, who in 297/8 had fought under Emperor Galerius in the last major conflict between Persia and Rome, began to consider this campaign is unclear, but textual and numismatic evidence suggests a date as early as 324 or 325,Footnote ⁶¹ around the same time that Eusebius’ account of the Battle of the Milvian Bridge in the Ecclesiastical History appeared in its final form. The later account in the Life of Constantine was composed in the aftermath of Constantine's death, when war had broken out between Rome and Persia: the Sassanian king Shapur II led an expedition into Roman Mesopotamia and besieged the frontier city of Nisibis for sixty-three days, whilst the late emperor's son, Constantius, assumed control of the Roman forces mustered for his father's campaign and fought the Persians intermittently for much of his reign.Footnote ⁶² Panegyrics composed by Libanius and Julian in honour of Constantius compare Shapur with Xerxes.Footnote ⁶³ For an ancient reader of Eusebius familiar with the recent hostility between Rome and Persia, the portrayal of Maxentius as the nonpareil Persian despot Xerxes must have had particular resonance. One might see in the portrayal an argument by analogy: just as Constantine had defeated Maxentius, the Persian king inside the empire, so he, or his descendants, would defeat Shapur, the Persian king outside it.

This article has suggested that Eusebius’ accounts of the Battle of the Milvian Bridge evoke Xerxes’ bridging of the Hellespont, an astonishing act recounted repeatedly by ancient authors. Later tellings of the tale were indebted to the authoritative accounts of Aeschylus and Herodotus, who, in describing Xerxes’ feat, employed a particular metaphor, that of the yoke. The yoke connoted dominance over two distinct but related realms, the physical and the political. In narrating the conflict between Constantine and Maxentius, Eusebius has been seen so far to employ yoke-language only in the former sense, to describe Maxentius’ boat-bridge over the Tiber. But towards the end of Eusebius’ accounts there appears one last yoke, and this time the word is used in its latter sense.Footnote ⁶⁴ To commemorate his victory, Constantine had a statue of himself, gripping a cross, displayed in Rome; the statue bore a Latin inscription presented in Greek by Eusebius: ‘By this saving sign, the true proof of bravery, I have liberated your city, saved from the yoke of the tyrant; even more, freeing the Senate and People of the Romans, I restored them to their ancient fame and brilliance.’Footnote ⁶⁵ This inscription aptly caps Eusebius’ accounts of the Battle of the Milvian Bridge, since the collapse of Maxentius’ boat-bridge, his yoking of the Tiber, marked the collapse of his tyranny, his yoking of Rome.