A Step Towards the Purple
There is little suggestion that Julian had an interest in becoming the emperor. He preferred to get lost amongst his books, but in 355, his world was turned upside down when he was declared Caesar of the West. Constantius believed he needed a representative in Gaul after recent rebellions, so he elevated Julian’s position as he was his last remaining male relative. Julian married Helena, the emperor’s sister, and was sent to Gaul with a small following.
While Julian unquestionably preferred the quiet life, he showed an aptitude for military command while in Gaul. In 356, he regained Colonia Agrippina and enjoyed a significant victory over the Alamanni in 357 at the Battle of Strasbourg. Further victories included a defeat of the Salian Franks of the Lower Rhine. The historian, Ammianus Marcellinus, is arguably the best source for information on Julian. According to Marcellinus, the Caesar took his role as military commander seriously and expected his men to handle rough conditions. For instance, he hated soldiers who slept on mattresses rather than on the cold stone floor.
Back home, Constantius was becoming more unpopular. He ordered his soldiers to attack religious dissenters, and an estimated 3,000 Christians were killed in a single day in Constantinople. By now, Julian was convinced that Christianity was corroding the might and steel of the Roman Empire. While in Gaul, Julian sacrificed to Bellona, the goddess of war.
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Constantius finally went too far when Emperor Shapur II of the Sassanid Empire invaded Mesopotamia and captured Amida after a siege lasting more than two months in early 360. Constantius went above Julian’s head by ordering the Caesar’s troops to the East. Julian’s men not only refused to follow the order, but they also threw their weight behind their leader. His elite troops, the wonderfully named Petulantes, wanted to stay and they held a crown over Julian’s head. At the camp of Lutetia, which is modern-day Paris, Julian was declared Augustus by his men.
Predictably, Constantius was outraged and immediately declared Julian a public enemy. Despite his new status, Julian’s work in Gaul wasn’t completed. He successfully campaigned against the Attuarian Franks from June to August. By the end of 360, Julian was openly flouting his Augustus title by issuing coins with the term; some of these coins didn’t have Constantius’ name on them. In early 361, Julian defeated the Alamanni and captured Vadomarius, their king. By now, the would-be emperor had clearly decided that he wanted to rule, after all, so he started capturing territory outside of Gaul. Julian claimed that he went down this path because Constantius had declared him a public enemy. Julian said that he merely wanted to frighten his rival so they could speak on friendlier terms.
If this was his aim, he miscalculated badly. Constantius realized that he had to face the ‘usurper’ by force even though he was still at war with the Sassanids. He gathered his forces and set off west to face Julian. He enjoyed initial success by taking the city of Aquileia but soon, the city was surrounded by an estimated 23,000 men loyal to Julian. The pretender remained in Naissus waiting for news, but the empire was spared civil war when Constantius died from a fever on November 3, 361. It has been suggested that he recognized Julian as emperor in his will. Whether it is true or not, nothing stood in the way of the new leader of the empire.