Synopsis: Ardeshir defeats Artabanus in battle and claims the Parthian Empire for the Sasanids. After a failed attempt to conquer Armenia, he sets his sights on the Roman East.
“Then (Ardeshir) came to battle with Artabanus, killed the entire army of the latter, seized their wealth, property, horses, and portable lodges, and settled himself in Istakhr. He collected soldiers in large numbers from Kerman, Mokristan, Isfahan, and different districts of Fars, and came to fight with Artabanus himself. So Artabanus sent for soldiers and provisions from different frontiers...But as the Glory of the Kayanians (Achaemenids) was with Ardeshir, the latter gained success. He killed Artabanus, whose entire wealth and property fell into the hands of Ardeshir, who married Artabanus's daughter, and went back to Fars.” – The Book of Deeds of Ardeshir Son of Pabag, Chapter IV
“Artaxerxes, a Persian, having conquered the Parthians in three battles and killed their king, Artabanus, made a campaign against Hatra, which he endeavored to take as a base for attacking the Romans. He did make a breach in the wall but, as he lost a number of soldiers through an ambuscade, he transferred his position to Media. Of this district, as also of Parthia, he acquired no small portion, partly by force and partly by intimidation, and then marched against Armenia. Here he suffered a reverse at the hands of the natives, some Medes, and the children of Artabanus, and either fled (as some say) or (as others assert) retired to prepare a larger expedition. He accordingly became a source of fear for us.” – Cassius Dio, Rome, Book 80 http://s407341505.onlinehome.us/Episode_B37_Shahanshah.mp3
Map of the Roman-Sasanid Frontier c. 232 AD: http://s407341505.onlinehome.us/SASANID_FINAL.jpg