Constantius II elevates his cousin Gallus to Caesar, and puts him in charge of the Eastern part of the Roman Empire.

Flavius Julius Constantius, better known to history as **Constantius II**, held the immense power of **Roman Emperor** from 337 to 361 CE. Born on August 7, 317, he inherited an empire undergoing profound change and spent his reign grappling with relentless external threats from the powerful **Sasanian Empire** in the East and various **Germanic peoples** along the northern frontiers. Internally, his rule was a turbulent period marked by repeated **civil wars**, intricate court intrigues, and dangerous usurpations, all of which underscore the challenging landscape of the 4th-century Roman world. His religious policies, particularly his strong promotion of Arian Christianity, further inflamed domestic conflicts that would resonate long after his death on November 3, 361.

From Prince to Emperor: Constantius II's Early Life and Ascension

As a son of the legendary **Constantine the Great**, the emperor who reshaped the Roman Empire, **Constantius II** was born into the heart of imperial power. He was formally elevated to the significant imperial rank of **Caesar** on November 8, 324, an early sign of his destined path. Following his father's passing, a complex succession unfolded. On September 9, 337, Constantius ascended to the senior title of **Augustus** alongside his brothers, Constantine II and Constans. To consolidate his newfound authority and eliminate potential rivals within the sprawling Constantinian dynasty, Constantius swiftly oversaw a brutal purge, resulting in the massacre of his father-in-law, an uncle, and several cousins. This ruthless act established his firm grip on power from the outset. With the empire divided among the three brothers, Constantius II received the vast eastern territories, encompassing Greece, Thrace, the Asian provinces, and the vital grain-producing region of Egypt.

Navigating Imperial Challenges: Wars and Intrigues

The Persian Front and Western Turmoil

For the ensuing decade, much of **Constantius II's** time and attention were consumed by a costly and largely inconclusive war against the **Sasanian Empire** to the east. This protracted conflict strained Roman resources and tested the loyalty of his legions. Meanwhile, far to the west, his brothers, Constantine II and Constans, engaged in their own bitter struggle for control over the empire's western provinces. This sibling rivalry ultimately led to the death of Constantine II in 340, leaving Constans as the sole ruler of the West. Despite the simmering tensions and the precarious nature of their shared rule, the two remaining brothers, Constantius and Constans, maintained an uneasy peace, a fragile balance of power that would not last.

Usurpation and Sole Rule

The fragile peace shattered in 350 when Constans was overthrown and assassinated by the ambitious usurper Magnentius. **Constantius II**, unwilling to accept Magnentius as a co-ruler and rightful emperor, immediately launched a devastating **civil war** to reclaim the entirety of the empire. This conflict culminated in two decisive and bloody battles: Mursa Major in 351 and Mons Seleucus in 353. Both engagements saw Constantius emerge victorious. After the latter defeat, Magnentius committed suicide, leaving **Constantius II** as the undisputed, sole ruler of the vast **Roman Empire**. This period marked the apex of his power, but also brought new challenges of governance and succession.

The Rise and Fall of Caesars

To assist in governing the vast eastern territories, **Constantius II** elevated his cousin, Constantius Gallus, to the subordinate rank of **Caesar** in 351. However, Gallus's violent and corrupt nature soon drew scathing reports, leading Constantius to order his execution just three years later. Not long after, in 355, Constantius looked to another family member for imperial support, promoting his last surviving cousin, Gallus's younger half-brother, Julian, to the rank of **Caesar**. This decision would later prove to be one of the most significant, and ultimately tragic, of his reign, setting the stage for a dramatic showdown.

Policies and Campaigns as Sole Emperor

Religious and Legal Policies

As the sole **Roman Emperor**, **Constantius II** aggressively pursued his religious convictions. He was a staunch proponent of the Arian interpretation of Christianity, a theological viewpoint that challenged the Nicene Creed and often put him at odds with orthodox bishops. His policies were clear: he banned pagan sacrifices throughout the empire, a significant move towards Christianizing Roman society, and issued new laws targeting Jewish communities. These policies illustrate his active role in shaping the religious landscape of his time, often inflaming existing tensions.

Military Triumphs and Renewed Conflicts

Beyond religious policy, **Constantius II** also demonstrated considerable military prowess. His campaigns against various **Germanic tribes** proved largely successful. In 354, he decisively defeated the Alamanni, securing a crucial frontier. He continued his military efforts across the Danube, campaigning successfully against the Quadi and Sarmatians in 357, solidifying Roman control over those volatile borders. The long-standing war against the **Sasanian Empire**, which had been in a lull since 350, erupted with renewed intensity in 359. The loss of several key border fortresses prompted **Constantius II** to travel east in 360, personally overseeing efforts to restore stability and push back the Persian advance.

The Final Years: Julian's Challenge and Constantius's Demise

While **Constantius II** was preoccupied with the eastern front, a new internal crisis emerged. In 360, his cousin **Julian**, whom he had earlier appointed Caesar, claimed the rank of **Augustus** for himself in Gaul. This audacious move plunged the empire to the brink of another **civil war**. Constantius attempted to persuade Julian to back down, but his efforts proved futile. As the two imperial armies began to maneuver for conflict, fate intervened. **Constantius II** fell gravely ill and died of a fever on November 3, 361, in Mopsuestia, an ancient city in Cilicia. Historical accounts suggest that on his deathbed, he recognized **Julian** as his rightful successor, thus averting what would have been a devastating internal conflict for the already beleaguered **Roman Empire**.

FAQs about Constantius II

Who was Constantius II?
Constantius II, born Flavius Julius Constantius, was a **Roman Emperor** who reigned from 337 to 361 CE. He was a son of **Constantine the Great** and played a crucial role in the post-Constantinian era, navigating constant warfare and significant internal strife.
When did Constantius II reign?
He reigned as **Roman Emperor** for 24 years, from September 9, 337, until his death on November 3, 361 CE.
What were the major challenges during his reign?
His reign was characterized by persistent warfare against the **Sasanian Empire** and **Germanic peoples** on the borders, frequent **civil wars** and usurpations internally (like the rebellion of **Magnentius**), and religious controversies, particularly his support for **Arianism**.
What was Constantius II's relationship with his family?
He was the son of **Constantine the Great**. His relationship with his brothers, Constantine II and Constans, was marked by initial power-sharing, then conflict and eventual sole rule after their deaths. He also appointed and later executed his cousin Gallus as **Caesar**, and later elevated another cousin, **Julian**, who eventually challenged his authority.
What were his key religious policies?
**Constantius II** was a staunch supporter of **Arianism**, a Christian theological view. He actively promoted this form of Christianity, banned traditional pagan sacrifices, and implemented laws against Jews, reflecting his commitment to shaping the religious landscape of the empire.
How did Constantius II die?
**Constantius II** died of a fever on November 3, 361 CE, in Mopsuestia, while preparing to confront his cousin **Julian**, who had claimed the title of **Augustus**. He is believed to have named Julian as his successor before his death.