For the whole of its existence, the province would remain a bone of contention between the Romans and their eastern neighbors, the Sassanid Persians, suffering heavily in the recurrent
Roman–Persian Wars. War broke out after the death of the Roman emperor
Decius in 251 and the province was invaded by the Persians. In the second half of the 250s, the Persian shah
Shapur I (r. ca. 240–270) attacked the Roman east, which was defended by the Roman emperor
Valerianus (r. 253–260), whom he
captured at
Edessa in 260.[2] In the next year however, Shapur was heavily defeated by
Odaenathus of
Palmyra and driven out of Osroene and Mesopotamia.[3]
It was taken and retaken several times. Being a province on the frontier it had a Roman legion stationed there,
Legio III Parthica and its Castrum (homebase) was
Resaena though there are some doubts on that fact.
Keser-Kayaalp, Elif; Drijvers, Hendrik J. W. (2018).
"Edessa". The Oxford Dictionary of Late Antiquity. Vol. 1. Oxford: Oxford University Press. pp. 516–518.
ISBN978-0-19-256246-3.
As found in the Notitia Dignitatum. Provincial administration reformed and
dioceses established by
Diocletian,
c. 293. Permanent
praetorian prefectures established after the death of
Constantine I. Empire permanently partitioned after 395. Exarchates of
Ravenna and
Africa established after 584. After massive territorial losses in the 7th century, the remaining provinces were superseded by the
theme system in c. 640–660, although in
Asia Minor and parts of Greece they survived under the themes until the early 9th century.