Constantius II, born Flavius Julius Constantius on August 7, 317, served as Roman Emperor from 337 to 361. He was one of the sons of Constantine the Great, and his reign was marked by near-constant warfare, both at the empire’s borders and within its own territories. During his rule, the Roman Empire faced repeated conflicts with the Sasanian Empire and Germanic tribes, while internal divisions led to civil wars, court intrigues, and the rise of several usurpers. Constantius II’s reign was complex, characterized by both military successes and political struggles that shaped the late Roman Empire.
In this article, we will explore the life and reign of Constantius II, from his early years as the son of Constantine the Great to his efforts to secure the borders of the empire and manage internal power struggles. We will also examine his role in religious conflicts within the empire, his relationships with his brothers and rivals, and his lasting legacy as a ruler of a turbulent Roman world.
Early Life and Rise to Power
Family Background and Birth
Constantius II was born on August 7, 317, in Sirmium (modern-day Sremska Mitrovica, Serbia). He was the second son of Constantine the Great and his second wife, Fausta. As the son of Constantine, Constantius was part of the Constantinian dynasty, which played a central role in shaping the Roman Empire during the 4th century. He grew up during a time of significant change, as his father converted to Christianity and worked to establish the faith throughout the empire.
Constantius was given the title of Caesar by his father in 324, along with his brothers, Constantine II and Constans. As a Caesar, Constantius was expected to assist in the administration of the empire and prepare for a future role as emperor. He gained valuable experience in military and political affairs, which would later prove crucial during his own reign.
Division of the Empire
When Constantine the Great died in 337, the Roman Empire was divided among his three sons: Constantine II, Constans, and Constantius II. The division of the empire was not without conflict, as each of the brothers sought to expand their power and influence. Constantius II received control over the eastern provinces, including the wealthy regions of Asia Minor, Syria, and Egypt. His brothers, Constantine II and Constans, controlled the western provinces.
Almost immediately, tensions arose between the three brothers, leading to civil conflict. Constantine II, who ruled over Gaul, Hispania, and Britannia, attempted to assert authority over his brother Constans, who controlled Italy and Africa. In 340, Constantine II invaded Italy, but he was defeated and killed by Constans’s forces. Constans then took control of the western half of the empire, leaving Constantius II as the ruler of the eastern half.
The Reign of Constantius II
Conflict with the Sasanian Empire
One of the defining features of Constantius II’s reign was the constant warfare on the empire’s eastern frontier against the Sasanian Empire. The Sasanians, under their ambitious king Shapur II, sought to expand their territory at the expense of Rome, leading to a series of conflicts that would last for much of Constantius’s reign. The war between Rome and the Sasanians was characterized by sieges, skirmishes, and shifting alliances, as both empires sought to gain the upper hand.
In 337, shortly after Constantius became emperor, Shapur II launched an invasion of Roman territory, capturing several important cities and fortresses. Constantius responded by leading military campaigns to defend the eastern provinces and regain lost territory. The war with the Sasanians was a draining conflict that required significant resources and manpower, but Constantius was able to achieve several notable victories, including the successful defense of Nisibis, a key city on the eastern frontier.
Despite these successes, the conflict with the Sasanians remained unresolved throughout Constantius’s reign. The constant threat of invasion from the east forced Constantius to maintain a large military presence in the region, which limited his ability to address other challenges facing the empire.
Civil Wars and Internal Struggles
In addition to the external threats from the Sasanian Empire, Constantius II faced numerous internal challenges during his reign. The death of his brothers, Constantine II and Constans, left Constantius as the sole surviving son of Constantine the Great, but it also led to new power struggles within the empire. In 350, a usurper named Magnentius rose to power in the west, overthrowing and killing Constans.
Magnentius’s usurpation led to a civil war between Constantius and Magnentius, as both sought to establish control over the entire Roman Empire. The conflict culminated in the Battle of Mursa Major in 351, one of the largest and bloodiest battles of the 4th century. Constantius emerged victorious, but the battle resulted in heavy losses for both sides, weakening the Roman military and further straining the empire’s resources.
After his victory over Magnentius, Constantius faced another challenge from Vetranio, a general who had declared himself emperor in the Balkans. Vetranio eventually submitted to Constantius, and the two reconciled, with Vetranio retiring from public life. By 353, Constantius had successfully eliminated all of his rivals and established himself as the sole ruler of the Roman Empire.
Religious Conflicts and the Arian Controversy
The Role of Christianity
Constantius II’s reign was also marked by significant religious conflict, particularly the Arian controversy, which divided the Christian Church. The controversy centered on the nature of Christ’s divinity and the relationship between God the Father and God the Son. The Arians, led by the theologian Arius, argued that Christ was a created being and therefore not co-eternal with the Father, while their opponents, the Nicene Christians, maintained that Christ was of the same substance as the Father.
Constantius, like his father Constantine, was deeply involved in the affairs of the Christian Church. However, unlike Constantine, who had supported the Nicene Creed, Constantius favored Arianism and worked to promote its acceptance throughout the empire. He convened several church councils in an attempt to resolve the Arian controversy, but his efforts often led to further divisions within the Church.
Constantius’s support for Arianism and his attempts to impose religious uniformity were met with resistance from Nicene bishops, including Athanasius of Alexandria, one of the leading defenders of Nicene orthodoxy. Athanasius was exiled multiple times during Constantius’s reign, as the emperor sought to suppress opposition to his religious policies. The conflict between Arians and Nicenes would continue to shape the Christian Church long after Constantius’s death.
Court Intrigues and the Rise of Julian
The Appointment of Julian as Caesar
In 355, Constantius II appointed his cousin Julian as Caesar and tasked him with defending the western provinces of the empire, which were under threat from Germanic tribes. Julian, who had been raised in relative obscurity following the execution of his father by Constantius, proved to be a capable military leader. He successfully repelled invasions by the Alamanni and Franks, securing the western borders and earning the loyalty of his troops.
Julian’s military successes and growing popularity made him a potential rival to Constantius, who became increasingly suspicious of his cousin’s intentions. In 360, Constantius ordered Julian to send a significant portion of his troops to the eastern front to assist in the war against the Sasanians. Julian’s soldiers, who were loyal to their commander, refused to comply with the order and instead proclaimed Julian as Augustus, effectively challenging Constantius’s authority.
Conflict with Julian
The declaration of Julian as Augustus led to a civil war between Constantius and Julian. Constantius, who was already engaged in a protracted conflict with the Sasanians, began to prepare for a confrontation with his cousin. However, before the two could meet in battle, Constantius fell ill and died on November 3, 361, in the city of Mopsuestia in Cilicia (modern-day Turkey). On his deathbed, Constantius named Julian as his successor, bringing an end to the civil war and ensuring a peaceful transition of power.
Legacy of Constantius II
A Reign of Constant Warfare
Constantius II’s reign was marked by nearly constant warfare, both on the empire’s borders and within its own territories. His efforts to defend the eastern frontier from the Sasanian Empire and his campaigns against internal usurpers required significant resources and manpower, which placed a heavy burden on the Roman state. Despite his military successes, Constantius’s reign was characterized by a sense of instability, as the empire faced numerous threats from both external and internal sources.
Religious Division and the Arian Controversy
Constantius’s involvement in the Arian controversy and his attempts to impose religious uniformity had a lasting impact on the Christian Church. His support for Arianism and his efforts to suppress Nicene opposition contributed to the deep divisions within the Church that would persist for centuries. The conflict between Arians and Nicenes shaped the development of Christian theology and had a significant influence on the religious landscape of the late Roman Empire.
The Transition to Julian
The appointment of Julian as Caesar and his eventual rise to power marked an important transition in the history of the Roman Empire. Julian, who would later become known as Julian the Apostate, sought to reverse many of the religious policies of Constantius and restore traditional Roman paganism. The conflict between Constantius and Julian highlighted the ongoing struggle for power within the Constantinian dynasty and the challenges faced by the Roman Empire as it sought to maintain unity in the face of internal and external pressures.
Conclusion
Constantius II’s reign as Roman Emperor was a period of significant challenges and complexities. From his early years as one of the sons of Constantine the Great to his efforts to defend the empire from external threats and manage internal power struggles, Constantius faced numerous obstacles that tested his leadership and resilience. His reign was marked by constant warfare, religious conflict, and court intrigues, which shaped the course of the Roman Empire during a turbulent period of its history.
While Constantius II’s legacy is often overshadowed by the achievements of his father, Constantine the Great, and the actions of his successor, Julian, his role in defending the empire and managing its internal divisions was crucial in maintaining the stability of the Roman state. The struggles and conflicts of Constantius’s reign highlight the challenges faced by the late Roman Empire as it sought to navigate a world marked by both external threats and internal divisions.