In a battle fought upon the river Lycus (Zab) in further Assyria he defeated the Parthian general, Indates, and raised a trophy in honor of his victory.

The exact scene of the other combats is unknown, but they were probably in the same neighborhood.

The result of them was the conquest of Babylonia, and the general revolt of the remaining Parthian provinces, which followed the common practice of deserting a falling house, and drew off or declared for the enemy.
Under these circumstances Phraates, considering that the time was come when it was necessary for him to submit or to create a diversion by raising troubles in the enemy's territory, released Demetrius from his confinement, and sent him, supported by a body of Parthian troops, to reclaim his kingdom.

He thought it probable that Antiochus, when the intelligence reached him, would retrace his steps, and return from Babylon to his own capital.

At any rate his efforts would be distracted; he would be able to draw fewer reinforcements from home; and he would be less inclined to proceed to any great distance from his own country.
Antiochus, however, was either uninformed of the impending danger or did not regard it as very pressing.