The years of comparative peace (353±356) Gallus, a cousin of Constantius, was made Caesar and placed in charge of the defence of the East in 351. Cf. Philostorgius, III, 25. His alleged success in keeping the Persians at bay: idem,1 III, 28 and Artemii Passio2 12. See also Zosimus III, 1, 1. Inroads of Saracens:3 Amm. XIV, 4, 1-7. Shapur meanwhile was preoccupied with campaigns against nomadic invaders from Central Asia: Amm. XIV, 3, 1 and XVI, 9, 3; general reduction in the scale of fighting (353 ff.): Amm. XVI, 9, 1. (354) Abortive Persian raid on Batna4 in Osrhoene by a Nohodares. Cf. Amm. XIV, 3, 1-4. Ursicinus5 was summoned from Nisibis by Gallus to investigate treason charges. Cf. Amm. XIV, 9, 1. Marriage between Olympias, daughter of the late Caesar Ablabius, to Arsaces, king of Armenia (c. 354): Athanasius, hist. Arian. 69, Amm. XX, 11, 3, see also XIV, 11, 4 and Faustus Buzandats‘i, Hist. Arm. IV, 15 and Moses Khorenats‘i, Hist. Arm. III, 21. (356) Sporadic Persian raids into Mesopotamia: Amm. XV, 13, 4 and Zos. III, 1, 1.