The Syrian troops, magnificently appointed and supported by a body of Jews under John Hyrcanus, advanced upon Babylon, receiving on their way the adhesion of many of the Parthian tributaries, who professed themselves disgusted by the arrogance and pride of their masters.  Phraates, on his part, advanced to meet his enemies, and in person or by his generals engaged Antiochus in three battles, but without success.  Antiochus was three times a conqueror.  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.  The winter was approaching; and, instead of withdrawing his troops from the occupied provinces and marching them back into Syria, he resolved to keep them where they were, merely dividing them, on account of their numbers, among the various cities which he had taken, and making them go into winter quarters.  It was, no doubt, his intention to remain quiet during the two or three winter months, after which he would have resumed the war, and have endeavored to penetrate through Media into Parthia Proper, where he might expect his adversary to make his last stand.

But Phraates saw that the position of affairs was favorable for striking a blow before the spring came.  The dispersion of his enemy’s troops deprived him of all advantage from the superiority of their numbers.  The circumstance of their being quartered in towns newly reduced, and unaccustomed to the rudeness and rapacity of soldiers and camp-followers, made it almost certain that complications would arise, and that it would not be long before in some places the Parthians, so lately declared to be oppressors, would be hailed as liberators.  Moreover, the Parthians were, probably, better able than their adversaries to endure the hardships and severities of a campaign in the cold season.  Parthia is a cold country, and the winters, both of the great plateau of Iran