Antoninus plundered Media by surprise attack, destroyed several forts, took Arbela and dug up the Parthian royal tombs, scattering the bones; the Parthians did not fight (Cassius Dio, Roman History 79(78).1.1)
Caracalla asks for the hand of the daughter of the Parthian king Artabanus. The king refuses, citing the two peoples' differing cultures, but wavers at gifts and oaths and consents. (Herodian, History of the Empire 4.10)
As he crosses the river into Parthian territory, the Parthians greet the bridegroom with garlands and music. Caracalla gives a signal, massacres the unarmed crowd and plunders. (Herodian, History of the Empire 4.11)
He winters at Edessa and plans to resume the war with Parthia (Historia Augusta Carac. 6.6)
Southern Europe (3)
Parthian campaign: pretext that Artabanus had refused to give his daughter; in truth he aimed at the Parthian kingdom (Cassius Dio, Roman History 79(78).1.1)
Caracalla builds splendid baths in Rome (the Baths of Antoninus), but has nothing else worth recalling. (Eutropius, Breviarium Eutr. 8.20)
Passing through the lands of the Cadusii and Babylonia, he wages guerrilla warfare with Parthian satraps and looses wild beasts upon the enemy (Historia Augusta Carac. 6.4)