Brighter and happier intimacies were those formed with the older bishop of Samosata, the Eusebius who, of all the many bearers of the name, most nearly realised its meaning,  and with Basil's junior, Amphilochius of Iconium. With the former, Basil's relations were those of an affectionate son and of an enthusiastic admirer. The many miles that stretched between Caesarea and Samosata did not prevent these personal as well as epistolary communications.  In 372 they were closely associated in the eager efforts of the orthodox bishops of the East to win the sympathy and active support of the West.  In 374 Eusebius was exiled, with all the picturesque incidents so vividly described by Theodoret.  He travelled slowly from Samosata into Thrace, but does not seem to have met either Gregory or Basil on his way. Basil contrived to continue a correspondence with him in his banishment. It was more like that of young lovers than of elderly bishops.  The friends deplore the hindrances to conveyance, and are eager to assure one another that neither is guilty of forgetfulness. 
 Bp. in 361. cf. Greg. Naz., Ep. xxviii. and xxix., and Theod., Ecc. Hist. xxvii.
 In 369, it is to the prayers of Eusebius, under the divine grace, that Basil refers his partial recovery from sickness (Ep. xxvii.), and sends Hypatius to Samosata in hope of similar blessing. (Ep. xxxi.)
 Ep. xcii.
 Ecc. Hist. iv. 14.
 cf. Principal Reynolds in D.C.B. i. 372.
 Epp. clvii., clviii., clxii., clxvii., clxviii., cxcviii., ccxxxvii., ccxxxix., ccxli., cclxviii.
Reference address : https://www.elpenor.org/basil/life-works.asp?pg=31