Magnentius in Harpers Dictionary of Classical Antiquities
A German by birth who conspired against the life of the
emperor Constans, whom he caused to be murdered in his bed.
Subsequently, being pursued by the vengeance of Constantius,
and defeated by him at the battle of Mursa (a. d. 351), he
took his own life by falling on his sword. His reign lasted
from A.D. 350 to 353. His full name was Flavius Popilius
Magnentius. See Victor, Caes. 41 and 42.