At the beginning of the sixth century Zosimus composed a history of the Roman empire that covered the period from the uncertainty over imperial succession in the early third century to the coming of the barbarians in the early fifth century. Constantine’s reign was hence at the chronological midpoint of his narrative, and in his discussion of the emperor, Zosimus highlighted civil wars. The first was against Maxentius in 312. According to Zosimus’ account, Constantine invaded Italy with an enormous army while Maxentius prepared to defend Rome with an army that was almost twice as large. His defense included the construction of a special breakaway timber bridge over the Tiber. Before the battle Maxentius consulted the Sibylline oracles while Constantine was heartened by seeing a propitious flock of owls on the city’s wall. After his troops were overwhelmed, Maxentius was thrown into the river when the bridge collapsed. The residents of Rome rejoiced when they saw Maxentius’ head on display at the end of a spear.
The second important civil war was against Licinius in 324. Several years earlier Constantine and Licinius had fought an inconclusive campaign. This time Constantine built a huge fleet in the harbor of Athens while Licinius mobilized ships contributed by regions around the eastern Mediterranean. Constantine’s army defeated Licinius’ forces in Thrace, and his fleet besieged the fleeing emperor in Byzantium. At his last stand outside Chalcedon, Licinius was again defeated and then surrendered. Although initially Constantine exiled his rival to Thessalonica, he soon had him executed.
Constantine’s preparations at Piraeus indicated that he was planning a war that would carry his forces into the heart of Licinius’ realm, assisted by a greatly enlarged fleet.
With the legacy of his father’s invasion of Britain still fresh in his mind as well as Maxentius’ more recent invasion of Africa, he may also have felt that he could draw from a reservoir of naval experience that his opponent would be hard-pressed to match. Given the record of hostility between the two regimes, surprise was not an appropriate tactic; massive advance planning was therefore the order of the day. Constantine was not a man to underestimate potential obstacles or to fail to take what he saw as the necessary steps to meet them. News that a fleet was building would give Licinius something to worry about. Was the plan for a direct assault or was it to land troops somewhere in the rear of his army? Anything that would inject a degree of uncertainty into Licinius’ deliberations would be useful-he had shown himself rather too competent when it came to a straight-up confrontation. Constantine’s invasion of the east began in the summer of 324. Meanwhile the empire still had to be governed, and it was to men like Locrius Verinus-last seen dealing with Donatists as vicarious of Africa and now prefect of Rome-that Constantine turned. One task that he allotted to an official named Dalmatius was to set down the ages at which young people would be considered mature; and Constantine himself sent an important missive to Severus, probably praetorian prefect at the time, telling him that people who merely purchased their ranks at the palace should be booted out-it was “fitting that only those who are employed in the palace or work in the administration should be selected for the bestowal of honors.”
The measure looks like a house-cleaning operation ahead of what would predictably be the complex task of integrating survivors of Licinius’ regime with his own people (Constantine appears to have been totally confident about the likely outcome of the campaign). The last communication on record as the campaign began is also to Verinus: it is a lengthy discussion on the subject of the appropriate rate of pay for swine-catchers.
The same texts that show Constantine in action also reveal a novel feature of the regime: the extensive involvement of members of his immediate family in positions of very great responsibility. One praetorian prefect this year who was traveling with him was one Flavius Constantius. We have no information as to who he was, but the fact that he shared two elements of Constantine’s name (the emperor was formally known as Flavius Valerius Constantinus) suggests that he was probably a blood relative. The Dalmatius mentioned in the preceding paragraph is likely Constantine’s half-brother, and his son Crispus, now in his early twenties, was in command of the fleet.
As Constantine and his family moved east with his entourage and troops, Licinius once again mustered his forces at Adrianople. Following the renewal of hostilities, Licinius established his army near the city of Adrianople (Edirne) in Thracia. His imperial rival soon marched against him from Thessalonica and encamped a short distance away on the opposite bank of the Hebrus (Maritsa) River. The following day, Licinius arrayed his army of 150,000 infantry and 15,000 cavalry on open ground to the north-west of the city near the confluence of the Tonoseius (Tunca) and Hebrus rivers, but Constantine was not willing to hazard a water crossing while his opponent waited in full battle formation. Over the course of the next days, the proximity of Licinius’ army prevented Constantine from traversing the river, as any attempt to cross the watercourse would place his army at the mercy of the awaiting eastern troops. He eventually settled upon a deception to move his army safely across the Hebrus. Upon learning of a location sufficiently narrow to permit men and horses to ford the river, the emperor ordered bridge materials collected at a location far removed from the chosen crossing point. With the enemy misled by the construction of the decoy, Constantine secretly gathered 5,000 infantry and archers and 800 cavalry on a wooded hill in preparation for an assault. He then led a select force of horsemen across the river at the predetermined place and charged Licinius’ formation. The unexpected attack threw the eastern legions into disorder, allowing time for the remainder of the western army to cross the Hebrus and reassemble for battle. There followed a difficult struggle that ended around sunset when Constantine’s men overran the enemy camp. By that time the main divisions of Licinius’ army were put to flight. Eastern losses amounted to almost 34,000 dead. The following morning, Constantine accepted the surrender of those defeated forces now scattered about in the countryside and throughout the immediate vicinity of the previous day’s fighting.
Constantine seems to have led the decisive attack himself, in the course of which he was wounded in the leg, while Licinius fled the field for the city of Byzantium. There he appointed a general called Martianus to command his forces on the far side of the Bosporus (the straits dividing Europe from Asia).
The record of Constantine’s wound reveals not only the continuing importance of the warrior ideology of the imperial position-it was just three years earlier that Nazarius had added Constantine’s secret scouting mission to the story of the Italian campaign-but also further problematizes the narrative of Eusebius. In his Life of Constantine the bishop reports that Constantine went into battle with the aid of a miraculous battle standard. Evidently visualized as taking the form of the labarum first mentioned in relation to the battle of the Milvian Bridge, this standard had amazing power. Carried into battle by fifty select guardsmen, it provided special protection for those around it: if the standard bearer should drop it in fear, the javelin coming his way would skewer him, while the man who then seized the standard was safe from all peril. The standard’s staff acted like a magnet, attracting javelins to itself so that it came to resemble a giant pincushion. As with the story of the cross in the sky before the Milvian Bridge, Eusebius claims Constantine himself as the source for this information “much later.” If this was the case and since Eusebius seemed not to know about the standard or the vision until a year before Constantine’s death when he wrote his speech celebrating the thirtieth anniversary of Constantine’s accession, one might wonder if “much later” in The Life of Constantine means “more than a decade later.” In 325 there seems to have been no need to Christianize this fast-moving narrative, or conceal the emperor’s injury.
With Licinius in Byzantium, the next phase of the campaign took place at sea: the western fleet was unmatchable, as Licinius’ admiral learned at his peril. Having lost control of the Bosporus, Licinius abandoned his men in Byzantium to take command of fresh forces near Chalcedon. Constantine landed his army without opposition north of Licinius’ position, forcing him to fight, probably on September 18, at a place called Chrysoplis (modern Üsküdar in Turkey). The result was now a foregone conclusion as Licinius was plainly outmatched. He fled to Nicomedia, and the troops who had been left in Byzantium surrendered, the campaign all but over. On or just before December 16, 324, Constantia, assisted by Eusebius (bishop of Nicomedia, no relation to Constantine’s biographer), negotiated the surrender of her husband. He was sent into exile at Thessalonica, where he was executed shortly afterward, allegedly for conspiring with barbarians.
Constantine was now sole ruler of the Roman Empire. He may have learned something of the art of government from his father, more perhaps from Diocletian. As we have seen, he knew how to govern: he guided his officials with a firm hand, and he understood his position as emperor within the tradition of imperial power that had developed over the centuries. But the victory of Constantine stemmed from more than just skill in the art of government, from more even than his extraordinary ability on the battlefield. Constantine’s victory stemmed from his own toughness and determination, qualities honed in the train of Diocletian but perhaps instilled earlier in the palace at Trier, or as his mother grasped her dignity and self-respect in the wake of rejection. Constantine had learned that there would be no one upon whom he could rely as much as he relied upon himself, and this is reflected in his belief in the god who guided him. Constantine’s god was still a very personal god, one whom he met on his own and who provided him guidance on an intensely personal basis; the god who Constantine believed to have guided him to victory was the god who had mercy upon him for his failings, and who protected him from evil.