Flavius Iulius Constantius was born at Sirmium (now Sremska Mitrovica in Serbia) in province of Pannonia, the third son of Constantine the Great, and second by his second wife Fausta, the daughter of Maximian. Constantius was made Caesar by his father on 13 November 324. The role of Constantius in the massacre of his relatives (those descended from the second marriage of his paternal grandfather Constantius Chlorus and Theodora) is unclear. Zosimus, writing 498-518 claims that Constantius “caused” the soldiers to murder his relatives, as opposed to actually ordering the action. Eutropius, writing between 350 and 370, writes that Constantius merely sanctioned “the act, rather than commanding it”. However, it must be noted that both of these sources are hostile to Constantius - Zosimus being a pagan, Eutropius a friend of Julian, Constantius’ cousin and, ultimately, his enemy. Whatever the case, Constantius himself, his older brother Constantine II, his younger brother Constans and three cousins, Gallus, his half-brother Julian and Nepotianus, son of Eutropia, were left as the only surviving males related to Constantine. Meeting at Sirmium not long after the massacre, the three brothers proceeded to divide the Roman Empire among them, according to their father's will. Constantine II received Britannia, Gaul and Hispania; Constans (initially under the supervision of Constantine II) Italia, Africa, Illyricum, Thrace, Macedon and Achaea; and Constantius the East.

Main Roman Coin Book and Other References:

RIC = Mattingly, Harold    The Roman Imperial Coinage
BMC = Coins of the Roman Empire in the British Museum
RSC = Seaby, H A    Roman Silver Coinage
RCV = Sear, David R    Roman Coins and Their Values
Cr = Crawford, Michael    The Roman Republican Coinage
SB = Sear, David R    Byzantine Coins and Their Values
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WW = Wildwinds.com (reference & attribution site)