surnamed the Younger, Roman emperor, A. D. 337-340, the second son of Constantine the Great, and the first whom he had by his second wife, Fausta, was born at Arelatum, now Aries, in Gaul, on the 7th of August, A. D. 312. As early as A. D. 316, he was created Caesar, together with nis elder brother, Crispus, and the younger Licinius, and he held the consulship several times. In commemoration of the fifth anniversary of his Caesarship, in 321, the orator Nazarius delivered a panegyric (Panegyr. Veter. ix.), which, however, is of little importance. In 335 he was entrusted with the administration of Gaul, Britain, and Spain. After the death of his father, 337, he received in the division of the empire between the three sons of the Great Constantine and his nephews, Dalmatius and Hannibalianus, the same provinces which he had governed under his father, and a part of Africa. Being the eldest surviving son of Constantine, he received some exterior marks of respect from the other emperors, but he had no authority over them. Dissatisfied with his share of the spoil, he exacted from his younger brother Constans the rest of Africa and the co-administration of Italy. Constans refused to give up those provinces. Constantine declared war against him, and invaded Italy by sea and by land, and at Aquileia met with the army of Constans, who approached from Dacia. Having rashly pursued the enemy when they gave way in a mock flight, Constantine was suddenly surrounded by them and fell under their swords. (A. D. 340.) His body was thrown into the river Alsa, but was afterwards found and buried with royal honours. He was twice married, but the names of his wives are not known; they probably both died before him, and he left no issue.