Flavius Iulius Constantius was born in 317 and was the second of Constantine’s three sons and was immediately named Caesar by his father.
Following the death of his father in 337 he instigated a massacre of all male relatives descending from his grandfather Constantius Chlorus, sparing his two brothers and two cousins Gallus and Julian.
In accordance with their fathers will, the three sons divided the empire between them. Constantius ruled the east while the western regions were divided between Constans and Constantine II.
While Constantius was in battle with the Sassanid’s, Constantine II was killed while trying to overthrow Constans and as a result Constans became sole ruler of the western half of the empire. This once again changed when Constans was killed in battle in 350, while fighting against Magnentius who had declared himself emperor. As Constantius was still in battle at this stage he decided to elevate his cousin Gallus to the position of Caesar to continue the battle with the Sassanid’s so he could take care of matters in the west.
The army led by Magnentius was crushed by Constantius in 351, and Magnentius committed suicide two years later. Gallus was eventually killed by Constantius but he soon realised he would not be able to handle the whole empire and was forced to elevate Julian to the position of Caesar in 355.
In 361, Julian was declared Augustus by his army in Gaul and as Julian and Constantius went to battle, Constantius fell ill with fever and soon died.
Julian became emperor of the entire empire.