Roman Civil War (432)
Part of Fall of the Western Roman Empire
Map of Africa and Italy
Date 432 Location Italia Result Victory of Aetius
Commanders and leaders
Bonifatius † Sebastianus	Aetius
Strength
7,000–10,000[1]	7,000–10,000

The Roman Civil War (432) was a military conflict between the Roman generals Aëtius and Bonifatius during the reign of Emperor Valentinian III. This war took place on Italian soil and was decided in the Battle of Rimini. Despite Aëtius losing the battle, the civil war ended in his favor, because Bonifatius was wounded in battle and eventually died of his injuries.^[2]

Besides the two generals, Galla Placidia was an important player as regentes. She made a not insignificant contribution to this conflict during her regency in the years 429 to 432. She was unable to prevent her two main generals from fighting each other instead of fighting the Vandals in present-day North-Africa and the Huns in Pannonia. With her decision in 432 to deprive Aetius of his command of the Roman army in favor of Boniface, she effectively created the basis for the arise of this conflict.

Boniface and Aetius were both ambitious generals who emerged in the turbulent period after the death of Emperor Honorius in 423. They became involved in a series of political and military confrontations, including Joannes (423-425) who was proclaimed emperor by the Senate against the heirs of Honorius: his wife Galla Placida with her minor son Valentinian and his cousin Theodosius II, emperor of the East Roman Empire. In 425, a civil war broke out that was won by the heirs of Honorius. After this, Aëtius, who supported John, was promoted away to the province Gallia and Boniface, a follower of Galla Placidia, ended up on a sideline.

Bonifatius disagreed the course of events as it went after the fall of John. Therefore he refused to leave his post in North Africa. Through his marriage to the Gothic Princess Pelagia, he had a private army of mainly Gothic Bucellari and the regular army in Africa, the Comitatenses, had remained loyal to him. This allowed him to be independent and to take his own course.

A new confrontation arose when a plot against Boniface was forged in 427. Bonifatius separated North-Africa from the empire. That period is known as the Civil war of 427-429. In this conflict, Boniface and the commander-in-chief of the Roman army Felix were each other's opponents. This conflict ended when Galla Placidia reconciled with Boniface. Aetius kept himself during this conflict aside until he was ranked to the rank of magister militum in 429. This was the junior rank of the two functions of comes et magister utriusque militiae, whose senior position was held by Felix, who was thus the most influential man in those years, and also a supporter of Galla Placidia.^[3]

After Bonifatius had left Ravenna in 429 to reconcile with Galla Placida, he returned to North Africa to campaign against the Vandals. They had conquered Mauretania Tingitana and Mauretania by 430 and now began to invade the Numidia region, where Bonifatius was waiting for them with his army. In the Battle of Calama, the Romans were defeated by the Vandals in early 430, after which Bonifatius withdrew to the city of Hippo Regius which was besieged from May 430. During the siege, the famous church father Augustinus died. After 14 months of siege, Bonifatius left the city to the Vandal King and withdrew to join forces with the East Roman general Aspar, who arrived from Constantinople with an army by sea. In early 432 they joined against Geiserik, but the Romans again were defeated.

Reportedly Felix began after the promotion of Aëtius, a conspiracy against him, but Aetius was Felix ahead and planned an assassination attempt.^[4] In May 430, Felix and his wife were murdered in the Ursiana Basilica in Ravenna.^[5] After Felix's death Aëtius obtained the position of senior magister militum. Nevertheless, he left Italy to return to Gaul, where he defeated an army of plundering Goths near Arles, turned around and began a campaign against plundering Iuthungi and Bagaudae in Raetia and Noricum. According to Wijnendaele, these actions of Aetius were carried out without the approval of the imperial government in Ravenna, and his campaigns in Gaul and Noricum were the result of the unwillingness of the army or of his Huns to participate in an overseas campaign against the Vandals in Africa. Instead of this he suppressed the raids in the north from where he easily could monitor the imperial seat of Ravenna, before campaigning against the Franks.^[6]

After the execution of Felix in 430, Aetius and Bonifatius remained as the most influential generals of the empire, both fighting for the favor of Placidia. In 432, Aetius held the consulate, an honorary function, but Bonifatius was recalled to Italy in that year, warmly received by Placidia and received the rank of patrician, also an honorary function. In addition, she gave him the senior comes et magister utriusque milities (commander-in-chief) position, while Aetius was deprived of his military command.^[7] With these decisions she created an explosive situation.

Aetius, who believed his fall was now imminent, openly revolted against the imperial authority in Ravenna. He marched from Gaul against Bonifatius who stayed in Ravenna. Aëtius had brought his own army from the West that he originally intended to deploy to the Suebi in Spain, while Bonifatius had some of his troops from Africa with him, most bucellarii and the Italian fieldarmy. The two warlords competed against each other five Roman miles outside of Arminium (the current city Rimini) in 432.^[8]

When the battle was over, Bonifatius had triumphed, but he would not enjoy his victory for long. He was injured during the battle and a few months later he died of a slaughter wound.

After Bonifatius' death, his son-in-law Sebastianus took over his position as commander-in-chief and continued the battle in Italy. He tried to capture Aëtius who had retreated to one of his fortified estates in Italy after the lost battle. However, Aëtius managed to flee and sought a good get-over with the Huns in Pannonia. Here he traveled to the court of his friend, the Hun King Rua, and after acquiring a new army, he returned to Italy.^[9]

With the help of this army, Aëtius became the winning party.^[10] He reconciled himself with Galla Placidia who again offered him the title of es et magister utriusque militias (commander-in-chief). Aetius then had Sebastianus exiled from Italy, seized the properties of Bonifatius and married his widow Pelagia. Aëtius eventually had become the great victorer of this civil war an also became the most important Roman of the west. Galla Placida no longer played a meaningful role and in 437 she had to take a Seat when her son Valentinianus III became an adult. Valentinianus would turn out to be a weak emperor.

With the death of Bonifatius, a period where several generals had fought for the power of the West Roman Empire, had come to an end. This episode would not be without consequences, because it eventually cost the empire the important provinces Mauretania Tingitana, Mauretania Caesariensis, Africa and Pannonia. Aëtius remained as the only one of the 'war lords' and had thus become the actual ruler, however he chose not to become emperor himself. With this decision, he broke the monopoly of the Western imperial government on violence, paving the way for future warlords- commanders and the disintegration of the Western army in the second half of the fifth century.^[11]

• Bury, John Bagnall (1923). History of the Later Roman Empire. Dover Books.
• Hughes, Ian (2020). Aëtius: Attila's Nemesis. Pen & Sword Military.
• McEvoy, Meaghan (2013). Child Emperor Rule in the Late Roman West, AD 367-455. Oxford University Press. p. 247.
• Wijnendaele, Jeroen P. (2016). Last of the Romans: Bonifatius - Warlord and Comes Africae. New York: Bloomsbury Academic.
• Wijnendaele, Jeroen P. (2017). "The early career of Aëtius and the murder of Felix (c. 425-430 CE)". Historia: Zeitschrift für Alte Geschichte. 66 (4): 468–482. JSTOR 45019274.