In the early 5th century, the Honorian regime, under Stilicho’s regency, confronted two invasions of the Italian peninsula. The first was led by Alaric, a Gothic leader who had exploited tensions between the eastern and western courts since his rebellion in 395. Despite previously being incorporated into the eastern military, Alaric unexpectedly invaded the western empire in 401. Stilicho managed to repel him after fierce battles at Pollentia and Verona, forcing Alaric into Noricum by 402.
The second invasion was orchestrated by Radagaisus, a Gothic king, around 405. Radagaisus led various barbarian groups from beyond the Danube into Italy, causing widespread devastation. Stilicho eventually cornered them in the mountains of Fiesole, where starvation led to their surrender. Radagaisus was executed, and his followers were either integrated into the Roman army or sold into slavery.
The motivations behind these invasions remain unclear. Claudian, Stilicho’s court panegyricist, offers no insights into Alaric’s decision to rebel again, portraying him as a typical barbarian driven by greed and destruction. Modern scholars suggest Alaric’s rebellion stemmed from a breakdown in relations with the eastern court, prompting him to seek power in the west. Radagaisus’ motives are even more obscure, with theories ranging from fleeing the Huns’ expansion beyond the Danube to seeking concessions from the Roman Empire. However, due to limited sources, conclusive explanations remain elusive.
To counter the threats posed to the Italian peninsula, Stilicho enacted decisive measures. When Alaric invaded in 401, catching the imperial court off guard, Stilicho swiftly journeyed to Raetia to muster sufficient forces. He not only recruited heavily from the non-Roman population along the Danube but also recalled several legions stationed in the western provinces, including one from Britain and notably all those guarding the Rhine limes. Although Claudian’s account might exaggerate the extent of Stilicho’s withdrawal of the Rhine legions, it’s reasonable to infer that Stilicho redirected veteran, mobile legions (comitatenses) to defend Italy, leaving only a minimal presence of regular frontier troops (limitanei) to manage affairs in the region. While specifics are lacking, it’s probable that Stilicho either retained these veteran legions in Italy after Alaric’s retreat or employed a similar strategy during Radagaisus’ invasion in 405. Concerns about Alaric’s potential return lingered at the imperial court until at least 404. Despite some Roman presence on the Rhine during the barbarian incursions of 406, the invaders’ relative success in penetrating Gaul suggests that Rhine defenses were operating at minimal levels.
Stilicho’s depletion of Gallic defenses was arguably a necessary response to the contemporary threats and ultimately proved effective against Alaric and Radagaisus. However, when coupled with Stilicho’s overall focus on eastern affairs, such actions amounted to a neglect of imperial governance in the Gallic provinces. This neglect created vulnerabilities for the Honorian regime, especially considering the recent usurpations of Maximus and Eugenius and the relatively recent extension of Theodosian dynasty control into the western empire. The potential for challenges to Italian authority was thus significant, though it may have been an unavoidable risk given the circumstances prevailing in Italy during the first half of the decade.
Stilicho’s policies unexpectedly led to a consequence that threatened the fragile control of the Honorian regime over the Gallic region. In late 406, Alans, Vandals, and Suebi crossed the Rhine frontier, causing widespread alarm in the northern Gallic provinces. Contrary to some interpretations, there is no evidence to suggest that this crossing was a result of issues elsewhere in the Roman Empire or beyond the Roman limes. Periodic barbarian raids were a common occurrence along the frontier, especially when the imperial government was preoccupied with internal matters or other external challenges. Typically, the imperial administration would address these raids once resources and attention became available. However, the incursions of 406 coincided with a new wave of Gallic usurpations and the divided focus of the central administration in Ravenna during the final phase of Stilicho’s regime, making the raids of lesser concern to the imperial government.
Our understanding of the 406 invaders, their entry into Gaul, and their subsequent actions is complicated by the nature of surviving source material. Primarily, we rely on brief chronicle accounts, a solitary letter from Jerome, and fragments of the work of fifth-century historian Renatus Profuturus Frigeridus as preserved in the later history of Gregory of Tours. While sixth-century historian Zosimus mentions these invaders as the catalyst for the British usurpations, his reference occurs in the unfinished and poorly edited Book VI of his Historia nova, and there are doubts about the reliability of his sources. Nevertheless, our limited sources suggest that the invaders operated independently upon reaching the Rhine frontier in 406 and displayed a tendency to fragment into smaller units based on obscure internal divisions when confronted with politically advantageous circumstances. These tendencies would continue to shape the groups’ history, particularly after their entry into the Spanish provinces in 409.
In a concise entry in his chronicle for the year 406, the contemporary Gallic theologian Prosper of Aquitane reports that on December 31, groups of Vandals and Alans crossed the Rhine and entered Gaul. The fragments of the fifth-century historian Renatus Profuturus Frigeridus, preserved in Gregory of Tours’ Historia, offer further insight into this event, revealing the political complexity and confusion underlying Prosper’s brief notice. Civil strife fractured the Alan contingent on the Rhine frontier, with Frigeridus recounting that the Alans divided their forces between their king, Respendial, and another commander named Goar. Instead of opposing the Romans, Goar and many of his followers opted to join Roman service, leading to a rift within the Alan ranks. This division prompted Respendial to alter his plans and temporarily withdraw from the Rhine. Meanwhile, a group of Franks inflicted heavy casualties on the Vandal contingent, even slaying their king, Godigisel. Only the arrival of the Alans, presumably those under Respendial, prevented the Vandals from suffering complete destruction.
Frigeridus’ account, though tantalizingly brief, sheds light on the dynamics of the Rhine crossing. While Goar is often identified as an Alan king in later literature, Frigeridus does not explicitly designate him as such during the Rhine crossing. His focus on Respendial’s title as king suggests that Goar may have been a prominent commander within Respendial’s Alan host. The mention of Goar’s potential involvement in aiding Paulinus of Pella in 414 suggests a gradual evolution of his status to that of a king. This underscores the evolving political landscape among non-Roman groups during this period.
Goar’s decision to align with the Romans indicates the continued presence of at least some Roman forces on the Rhine frontier. After securing Goar’s support, Roman opposition apparently grew formidable enough to dissuade Respendial from crossing the Rhine at his intended location. Meanwhile, the Vandals attempted to cross at a different point, where they encountered a group of Franks. Although it is widely accepted that these Franks were allied with or federated to the Romans, Frigeridus and the Spanish historian Orosius do not explicitly confirm this. Nonetheless, it is evident that the Alans and Vandals initially acted independently, targeting frontier defenses in different areas. Respendial only intervened to assist the Vandals after realizing he could not withstand the Roman forces alone, leading the two groups to cross the Rhine together.
While Prosper and Frigeridus do not mention the Suebi, other sources suggest they constituted a third major division among the barbarians entering Gaul in the winter of 406. Traditionally considered part of the Alamannic confederation, the Suebi’s involvement is hinted at by Jerome in his letter 123 to the Gallic noblewoman Ageruchia, dated around 409. However, Jerome’s ethnographic list includes several groups not mentioned elsewhere, casting doubt on the accuracy of his account regarding the perpetrators of the Rhine crossing.
Hydatius provides unique insights into further changes in the political landscape of the barbarian groups following their entry into Spain in 409. In his account of the division of Spanish provinces among the barbarians in 411, Hydatius specifies that the Vandals comprised at least two distinct groups. The dominant faction, known as the Siling Vandals, received the province of Baetica for settlement. The second group, presumably smaller in number based on their allotted territory, shared the province of Gallaecia with the Suebi. This division among the Vandals, along with their subsequent reunification after 416, illustrates the fluidity of political and cultural identities among these groups over time and across different regions.
Zosimus, a sixth-century historian, asserts that the Rhine invasion in 406 directly influenced the contemporaneous British usurpations. According to Zosimus, the depredations of the invaders in the Gallic provinces prompted fear among the soldiers stationed in Britain, leading them to support the usurpation of imperial power rather than risk an invasion from across the channel. Zosimus details the sequence of these usurpers, beginning with Marcus, followed by Gratian, and culminating in Constantine in early 407. This account is corroborated by the ecclesiastical historian Sozomen and a surviving fragment of their shared source, the lost history of Olympiodorus.
However, Zosimus’ assertion of a cause-and-effect relationship between the Rhine crossing and the British usurpations is chronologically inconsistent with other sources. Prosper of Aquitaine specifically dates the Rhine crossing to December 31, 406, while Olympiodorus indicates that the British usurpations began before January 1, 407. As Constantine’s proclamation and crossing from Britain to the continent occurred in early 407, it suggests that the British rebellion was already underway before the raiders breached the Roman limes. Therefore, according to the testimonies of Prosper and Olympiodorus, the Rhine crossing of the Vandals, Alans, and Suebi could not have directly caused the sequence of British usurpations.
Scholars have proposed various solutions to reconcile the contradiction between Prosper’s date for the Rhine crossing and Zosimus’ claims regarding its relationship to the British usurpations. François Paschoud suggests that Zosimus originally detailed two barbarian invasions of the Gallic provinces in 406, with the first invasion causing the British usurpations and the second being the Rhine crossing of Alans, Vandals, and Suebi on December 31, 406. On the other hand, Michael Kulikowski, following Norman Baynes’ earlier theory, argues that Prosper’s date for the Rhine crossing should be interpreted as the last day of 405 rather than 406. Both theories have garnered support among scholars.
However, the crux of the issue may lie in the notion that Zosimus’ narrative after 404 largely follows the lost work of Olympiodorus, a historian known for his reliability.
After assuming the imperial purple, Constantine crossed to the continent at Bononia (modern-day Boulogne) in early 407, swiftly gaining the allegiance of the majority of the Gallic army and influential senators. He effectively contained the Alans, Vandals, and Suebi in the two Belgicas in northern Gaul for three years through a combination of military strategies, diplomatic negotiations, and possibly military recruitment.
Constantine also took measures to strengthen the Rhine frontier and received recognition as emperor in southeastern Gaul and Spain. The minting of his initial coins at Lyons suggests that this city may have been his primary target during the initial phase of his invasion. Unlike previous usurpers, Constantine maintained a policy of seeking conciliation and alliance even after initial rejection, displaying aspirations towards compromise by positioning himself within the legitimate imperial college on his coinage.
This conciliatory approach may have contributed to the slower progress of his invasion. Constantine’s temporary pause in the winter of 407/408 before capturing Arles, possibly a temporary capital of the Gallic Prefecture, could have been interpreted as a further peace overture to the imperial court. However, this pause nearly resulted in the end of his revolt in its first year, as Stilicho’s general Sarus managed to besiege Constantine in Valence. Only the timely arrival of reinforcements under the command of Edobich and Gerontius forced Sarus to retreat into Italy.
In the spring of 408, Constantine successfully captured Arles, prompting Honorian loyalists to flee to Ravenna. Meanwhile, in Spain, relatives of the Theodosian house organized a rebellion in Lusitania. Constantine appointed his eldest son, Constans, as Caesar and sent him, along with the Master of Soldiers in Gaul (MVM) Gerontius and the newly appointed praefectus praetorio per Gallias (PPO) Apollinaris, to suppress the revolt. After an initial defeat, Constans and Gerontius crushed the rebellion, delivering its leaders to Constantine in Arles. However, Constantine’s decision to execute Didymus and Verinianus strained his later negotiations with Honorius for imperial recognition.
At the outset of the year 409, Constantine held sway over Gaul and Spain without significant opposition. The death of Stilicho in 408 had left the administration in Italy weakened and unable to effectively address the situation in Gaul. Moreover, Ravenna’s indecisiveness regarding Alaric had allowed the Gothic general to exert pressure directly on Rome. In this context, Constantine began to assert his influence in Italian affairs.
Following the collapse of Stilicho’s regime, Olympius assumed control of the imperial administration and adopted a hostile stance towards Alaric. This stance led to the rejection of Alaric’s peaceful overtures, culminating in Alaric’s invasion of Italy and the first siege of Rome. However, the Roman Senate managed to negotiate a temporary peace with Alaric in late 408, which Honorius agreed to.
In early 409, Constantine dispatched an embassy to Ravenna seeking Honorius’ recognition as co-emperor. Fear for the safety of his relatives and the looming threat of Alaric led Honorius to reluctantly recognize Constantine. This recognition prompted the imperial court to revert to a hostile stance towards Alaric. However, delays in fulfilling the terms of the treaty with Alaric and Olympius’ opposition to peace efforts led to renewed hostilities with Alaric.
Constantine’s offer of assistance against Alaric likely influenced the imperial court’s decisions regarding the Gothic threat. Despite the strained relations caused by the execution of Honorius’ relatives, Constantine’s second embassy sought to reaffirm the peace agreement. However, internal political developments, including Olympius’ fall from power and Gerontius’ rebellion in Spain, complicated the situation.
Gerontius’ revolt in Spain, coupled with the renewed incursions of the Alans, Vandals, and Suebi, weakened Constantine’s hold over Gaul. The ensuing chaos led to the collapse of Roman authority in Britain and Armorica, as local communities rejected Constantine’s rule and expelled Roman magistrates. This rejection did not signify a rejection of Roman governance per se but rather a rejection of Constantine’s regime.
In conclusion, the events of 409 saw Constantine’s influence extend into Italian affairs, but internal revolts and external threats ultimately undermined his control over Gaul and Spain, leading to the collapse of Roman authority in certain regions.
Following Gerontius’ revolt in the spring or summer of 409, the sequence of events becomes blurred in the sources, leading to varying scholarly interpretations. Some place Gerontius’ elevation of Maximus to the purple in the summer of 410, while others associate it with the beginning of Gerontius’ revolt in 409. The timing of Constans’ elevation to Augustus is also debated, with some placing it in 409 and others in 410.
However, it’s likely that Gerontius raised Maximus immediately after initiating his revolt in 409, as revolting against an established regime would necessitate offering a new imperial figure for his troops to rally behind. After driving Constans and the Constantinian loyalists from the Iberian Peninsula, Gerontius made peace with non-Roman groups who had crossed the Pyrenees in late 409.
In late 409 or early 410, Constans returned to his father at Arles. Meanwhile, Constantine, in the process of preparing for his Italian campaign, raised Constans to Augustus and reorganized his administration. Constans may have later departed for a campaign against Gerontius in Spain, though this is debated among scholars.
In the summer of 410, Constantine marched from Arles into northern Italy but faced setbacks due to factional conflicts in Honorius’ court. With the death of Allobich, Constantine reconsidered his campaign and retreated to Arles.
Back in Gaul, Constantine encountered his son Constans, who had returned from Spain after a defeat by Gerontius. Despite their reunion, their peace was short-lived as Gerontius launched a campaign into Gaul against them.
The Italian army, under Constantius and Ulfilas, entered Gaul in the spring of 411 to confront Constantine at Arles. However, news of Jovinus’ usurpation and the march of an army against them forced Constantine to renounce his title and seek sanctuary. Constantine and his son Julian were captured and executed by Honorius.
The fall of Constantine did not bring immediate stability to Gaul, as Jovinus’ usurpation posed a new threat. Constantius and Ulfilas withdrew to Italy, allowing Jovinus to establish his regime in Gaul. However, this respite was short-lived, as Athaulf’s entry into Gaul in 412 would ultimately lead to the downfall of Jovinus’ administration and the emergence of a new Theodosian regime in the western empire.