His supplies failed, and he had to feed his troops on barley instead of wheat.

Meantime the autumnal equinox was approaching, and the weather was becoming cold.

The Medes and Parthians, under their respective monarchs, hung about him, impeded his movements, and cut off his stragglers, but carefully avoided engaging him in a pitched battle.

If he could have forced the city to a surrender, he would have been in comparative safety, for he might have gone into winter quarters there and have renewed the war in the ensuing spring.

But all his assaults, with whatever desperation they were made, failed; and it became necessary to relinquish the siege and retire into Armenia before the rigors of winter should set in.