Excerpts from Books and Wikipedia
"His reign saw constant warfare on the borders against the Sasanian Empire and Germanic peoples, while internally the Roman Empire went through repeated civil wars and usurpations, culminating in Constantius' overthrow as emperor by his cousin Julian. His religious policies inflamed domestic conflicts that would continue after his death. The second son of Constantine I and Fausta, Constantius was made Caesar by his father in 324. He led the Roman army in war against the Sasanian Empire in 336. A year later, Constantine I died, and Constantius became Augustus with his brothers Constantine II and Constans. . . . The brothers divided the empire among themselves, with Constantius receiving the eastern provinces. In 340, his brothers Constantine and Constans clashed over the western provinces of the empire. The resulting conflict left Constantine dead and Constans as ruler of the west. . . . Constans was overthrown and assassinated in 350 by the usurper Magnentius." Constantius warred against the usurper & defeated him. "As emperor, Constantius promoted Arian Christianity, persecuted pagans by banning sacrifices and closing pagan temples and issued laws discriminating against Jews." [Wikipedia]