Constantine III (Western Roman emperor)

Constantine III, originally a common Roman soldier, was proclaimed emperor in Roman Britain in 407 before securing a position in Gaul. His tenure saw him acknowledged as co-emperor of the Roman Empire between 409 and 411.

Constantine & Roman Britain

Beginning his ascent as part of Britain’s field army, Constantine was hailed emperor and swiftly transitioned to Gaul, taking key military forces with him. There, he engaged in both combat and negotiations to stabilize and assume control over Gaul and Hispania, designating Arles as his capital. Despite initial opposition from Honorius, the Western Roman Emperor, who dispatched Sarus the Goth to challenge him, Constantine managed to hold his ground. His rule in Hispania was briefly contested, but was reasserted by his general, Gerontius. By early 409, Honorius recognized him as co-emperor, a status Constantine extended to his eldest son, Constans II.

Gerontius’s revolt in 409, however, marked the beginning of the end for Constantine III. After Gerontius declared Maximus as emperor and instigated uprisings in Gaul, Constantine faced setbacks, including an unsuccessful invasion of Italy and the defeat and death of Constans in Hispania. Eventually, besieged in Arles by Gerontius, his situation worsened until Honorius’s new general, Flavius Constantius, captured the city. Betrayed by a promise of safety, Constantine was executed, with his head delivered to Honorius.

Background context highlights the division of the Roman Empire following Theodosius I’s death in 395, with Honorius ruling the West under the influence of general Stilicho. This period saw Roman Britain facing raids and the gradual withdrawal of Roman military support, setting the stage for Constantine III’s rise amidst the Empire’s broader struggles with barbarian invasions and internal dissent.

Little is known of Constantine III before his acclamation as emperor, with his personal life largely a mystery. His rise from the ranks in 406, amid Britain’s military dissatisfaction, showcased a desperate attempt for stability as the Western Roman Empire faced significant threats. This bid for leadership, initially viewed as another short-lived revolt, unexpectedly led to a substantial challenge to Roman authority in Gaul, demonstrating Constantine’s fleeting, yet impactful, mark on history.


As co-emperor, Constantine III was depicted on a siliqua, a type of silver coin, showcasing his profile on one side and a stylized figure with a spear and globe on the reverse, symbolizing his victories. By May 408, Constantine had established Arles as his capital, assimilating the existing imperial administration and minting a significant quantity of high-quality coins, possibly from bullion seized during Sarus’s retreat. This act was part of his strategy to position himself as an equal to both the Western and Eastern Emperors.

Constantine elevated his oldest son, initially a monk, to the rank of Caesar, giving him the imperial name Constans and arranging a marriage to secure a dynasty. In early 408, Constans, alongside General Gerontius, was dispatched to Hispania, a territory with strong ties to the House of Theodosius, which had initially fallen under Constantine’s control without much resistance from Honorius’s relatives. Following a brief challenge from Didymus and Verinianus, Constantine’s forces reasserted control, with Constans establishing a base in Saragossa.


The political landscape was tumultuous, with Honorius’s dealings with the Visigoths and internal strife, including the execution of Stilicho and a mutiny within the Roman army. Constantine’s acknowledgment as co-emperor by Honorius in late 408, amidst these crises, marked a peak in his reign, with both sharing consulship in 409 and Constantine raising Constans to co-emperor.

However, Constantine’s decline began with Apollinaris’s replacement and Constans’s second mission to Hispania, where Gerontius rebelled, proclaiming Maximus as emperor. The ensuing conflicts across Gaul and Hispania, combined with Saxon raids on Roman Britain, underscored the eroding Roman authority. Constantine’s fall was precipitated by the siege of Arles, led by Gerontius and then by Honorius’s newly appointed general, Flavius Constantius. Despite a promised safe passage, Constantine was executed in 411, a grim end to his bid for power.


In the aftermath, Constantius managed to stabilize the Western Empire, suppressing revolts and securing Roman territories, except for Britain, which remained beyond Roman control. Constantius’s marriage to Galla Placidia and his brief reign as co-emperor underscored the transient nature of power in the late Roman Empire, culminating in the ascension of Valentinian III.