Editing Shapur II (section)

=== Early campaigns and first war against the Romans ===
{{main|Perso-Roman wars of 337–361}}

[[File:British Museum Shapur II Plate.jpg|thumb|right|Gilded silver plate showing a king (identified as Shapur II) hunting a deer whilst riding a stag, in the [[British Museum]]]]
In 337, after the accession of [[Constantius II]] to the Roman throne, Shapur II, provoked by the Roman rulers' backing of Armenia{{sfn|Daryaee|2014|p=17}} and the Armenian kingdom's earlier [[Christianization of Armenia|conversion to Christianity]],{{Sfn|Daryaee|2009}}{{Efn|Lee E. Patterson writes, "That Armenia should officially become Christian 
was troubling mainly because such a transformation aligned it with 
the Romans even more than before."{{Sfn|Patterson|2017|p=191}}}} broke the peace concluded in 298 between [[Narseh]] (293–302) and [[Diocletian]] (284–305), which had been observed for forty years. Most of the fighting during this campaign occurred in Roman Mesopotamia, where Roman fortifications impeded the Persian advance.{{Sfn|Frye|1983|pp=130–131, 137}} Nevertheless, Shapur was able to take some forts, such as Vitra.{{sfn|Daryaee|2014|p=17}} Persian forces also devastated Armenia and captured and blinded the Armenian king [[Tiran of Armenia|Tiran]], perhaps in 350. Shapur besieged the Roman fortress city of [[Nusaybin|Nisibis]] in Mesopotamia thrice (in 338, 346, and 350) and was repulsed each time.{{Sfn|Garsoïan|1997|pp=85–86}} During this campaign, the sole engagement between the sides' main armies was the [[Battle of Singara (344)|Battle of Singara]] (modern-day [[Sinjar]], Iraq) in 344, where Persian forces feinted a retreat and inflicted significant losses on the Roman army.{{Sfn|Potter|2004|pp=468, 690, note 140}}{{Efn|The date of the battle is disputed, and some scholars have suggested that there were actually two battles of Singara. See the references in {{harvnb|Potter|2004|p=690, note 140}} and {{harvnb|Dodgeon|Lieu|2005|pp=329–330}}. According to Potter, K. Mosig-Walburg conclusively demonstrated that there was one battle in 344 in the article "Zur Schlacht bei Singara," ''Historia'' 48 (1999): 330–84.{{Sfn|Potter|2004|p=690, note 140}}}} Neither side managed to achieve a decisive advantage, and an invasion of Central Asian nomads in the east forced Shapur to abandon his campaign against Rome by 350.{{Sfn|Daryaee|2009}} These nomads were likely the [[Kidarites]], who were threatening the [[Gupta Empire]] (320–500 CE) in India at the same time.{{sfn|Daryaee|2014|p=17}} After an extended campaign against the nomads, Shapur forced their king, [[Grumbates]], into an alliance,{{Sfn|Meyer|1911}} thus gaining a new ally against the Romans.{{Sfn|Daryaee|2009}} In particular, Grumbates's forces joined the Persians in the [[Siege of Amida (359)|Siege of Amida]] in 359.{{sfn|Daryaee|2014|p=18}}