He invaded Parthia at the head of an army consisting of his own subjects, and engaged Vonones, to whom in his difficulties the bulk of the Parthian people had rallied.

The engagement resulted in the defeat of the Median monarch, who returned to his own country, and, having collected a larger army, made a second invasion.
This time he was successful.

Vonones fled on horseback to Seleucia with a small body of followers; while his defeated army, following in his track, was pressed upon by the victorious Mede, and suffered great losses.

Artabanus, having entered Ctesiphon in triumph, was immediately proclaimed king.

Vonones, escaping from Seleucia, took refuge among the Armenians; and, as it happened that just at this time the Armenian throne was vacant, not only was an asylum granted him, but he was made king of the country.