After his death, however, another of his sons, named Ardashir, refused to submit to his brother, and rose in revolt; about which time Sapor died--we can hardly suppose by accident. That Ardashir found his brothers in his way and slew them, is so definitely affirmed by well authenticated tradition that we cannot entertain a doubt that such was the case. The empire of the Sassanids begins with Ardashir, just as that of the Achæmenides begins with Cyrus, whose forefathers had likewise been kings. His name, of which Artachshathr is the older form, is the same as that which the Greeks rendered by Artaxerxes. It is a remarkable fact that in the native home of the Achæmenides, who are otherwise unknown to genuine Persian tradition, the ancient royal names should have survived in common use; for several princes of the pre-Sassanid period were named Artaxerxes and Darius (Darjaw, Darao, Dara). According to a fairly probable estimate, Ardashir’s first appearance as king should be assigned to the year 211-12 A.D. [Sidenote: [211-233 A.D.]] That he had hard work to exalt himself from prince of Persis to “king of the kings of Iran” is recognised by tradition. He first made himself master of the province of Carmania, which lies east of Persis, then of Susiana, then of the small kingdom about the mouth of the Tigris. The resistance which he had to overcome in the first instance was offered by local sovereigns, not by the Parthian king, whose power was restricted to an enormous extent by his nobles and vassals. Ultimately, however, Ardashir came into conflict with him also. According to Dion Cassius,[c] a contemporary, we are led to believe that Ardashir defeated the Parthians in three battles. His decisive encounter with Ardavan (Artabanus), the last Parthian Great King, probably took place on April 22nd, 224 A.D.[30] Ardavan fell in the battle, and from that time forward Ardashir assumed the title of “king of kings,” which from ancient days had been borne by the ruler of the empire of anterior Asia. All the evidence points to the decisive battle having taken place in Babylonia or Susiana. This would fit in with Dion’s statement that the first expedition afterwards undertaken was directed against Atra, in the midst of the Mesopotamian desert, where a small independent state had come into being in the near neighbourhood of the Parthian capital. At first Ardashir beat in vain upon the walls of Atra, whose strength can still be seen from the mighty ruins that remain, but the place was soon taken and destroyed either by him or his successor. He succeeded in conquering Media, where he was opposed by a scion of the Arsacid family, and the greater part of the Iranian highlands; but not Armenia, whither sons of Ardavan had fled.