The siege was short; the place was considered strong; the nearest point held by a powerful Roman force was Nisibis, which was at least sixty miles distant from Singara.

The neighborhood of Singara was, moreover, ill supplied with water; and a relieving army would probably have soon found itself in difficulties.

Singara, on the verge of the desert, was always perilously situated.

Rome valued it as an outpost from which her enemy might be watched, and which might advertise her of a sudden danger, but could not venture to undertake its defence in case of an attack in force, and was prepared to hear of its capture with equanimity.
From Singara Sapor directed his march almost due northwards, and, leaving Nisibis unassailed upon his left, proceeded to attack the strong fort known indifferently as Phoenica or Bezabde.

This was a position on the east bank of the Tigris, near the point where that river quits the mountains and debouches upon the plain; though not on the site, it may be considered the representative of the modern Jezireh, which commands the passes from the low country into the Kurdish mountains.