or, with his full name, FLAVIUS CLAUDIUS (JULIUS) CONSTANTIUS GALLUS, the son of Julius Constantius and Galla, grandson of Constantius Chlorus, nephew of Constantine the Great, and elder brother, by a different mother, of Julian the Apostate. (See Genealogical Table, vol. I. p. 832.) Having been spared, in consequence of his infirm health, in the general massacre of the more dangerous members of the imperial family, which followed the death of his uncle, and in which his own father and an elder brother were involved, he was, in A. D. 351, named Caesar by Constantius II., and left in the east to repel the incursions of the Persians.
The principal events of his subsequent career, and the manner of his death, which happened A. D. 354, are detailed elsewhere. [CONSTANTIUS II., p. 848.]
The appellation of Gallus was dropped upon his elevation to the rank of Caesar (Victor, de Caes.
42), and hence numismatologists have experienced considerable difficulty in separating the medals ot this prince from those of his cousin, Constantius II., struck during the lifetime of Constantine the Great, since precisely the same designation, CONSTANTIUS CAESAR, is found applied to both. Several of the coins of Gallus, however, have the epithet IVN. (junior) appended by way of distinction, and others are known by FL. CL., or FL. IVL, being prefixed, since these names do not appear to have been ever assumed by the elder Constantius. For more delicate methods of discrimination where the above tests fail, see Eckhel, vol. viii. p. 124.