After crushing a rebellion in the south, Shapur II invaded Roman Mesopotamia and captured Armenia. Apparently, nine major battles were fought. The most renowned was the inconclusive Battle of Singara (modern Sinjar, Iraq) in which Constantius II was at first successful, capturing the Persian camp, only to be driven out by a surprise night attack after Shapur had rallied his troops (344 or 348?). The most notable feature of this war was the consistently successful defence of the Roman fortress city of Nisibis in Mesopotamia. Shapur besieged the city thrice (in 338, 346, 350 CE), and was repulsed each time.
After crushing a rebellion in the south, Shapur II invaded Roman Mesopotamia and captured Armenia. Apparently, nine major battles were fought. The most renowned was the inconclusive Battle of Singara (modern Sinjar, Iraq) in which Constantius II was at first successful, capturing the Persian camp, only to be driven out by a surprise night attack after Shapur had rallied his troops (344 or 348?). The most notable feature of this war was the consistently successful defence of the Roman fortress city of Nisibis in Mesopotamia Shapur besieged the city thrice (in 338, 346, 350 CE), and was repulsed each time.