His reign was marked by continued border warfare with
Persia and by civil wars and usurpations. Constantius II was a competent
military leader; while he was stalemated against the Persions he was
very successful within the Empire, putting down all rivals who faced
him.
He passed away from a fever in the city of Mopsuestia in Cicilia
(Anatolia, Turkey). He was leading his legions to join battle with
the forces of his young cousin Julian who he had named as Caesar of the
West, after the Western legions had proclaimed Julian the Western
Emperor. On his deathbed Constantius II was baptized, and declared
Julian
to be his rightful successor. This left Julian II
as Emperor of both the Eastern and Western empires.