The main body, much relieved by the diminution of the pressure upon them, had waited patiently for Publius to return in triumph, regarding the battle as well-nigh over and success as certain. After a time the prolonged absence of the young captain aroused suspicions, which grew into alarms when messengers arrived telling of his extreme danger. Crassus, almost beside himself with anxiety, had given the word to advance, and the army had moved forward a short distance, when the shouts of the returning enemy were heard, and the head of the unfortunate officer was seen displayed aloft, while the Parthian squadrons, closing in once more, renewed the assault on their remaining foes with increased vigor. The mailed horsemen approached close to the legionaries and thrust at them with the long pikes while the light-armed, galloping across the Roman front, discharged their unerring arrows over the heads of their own men. The Romans could neither successfully defend themselves nor effectively retaliate. Still time brought some relief. Bowstrings broke, spears were blunted or splintered, arrows began to fail, thews and sinews to relax; and when night closed in both parties were almost equally glad of the cessation of arms which the darkness rendered compulsory. It was the custom of the Parthians, as of the Persians, to bivouac at a considerable distance from an enemy. Accordingly, at nightfall they drew off, having first shouted to the Romans that they would grant the general one night in which to bewail his son; on the morrow they would come and take him prisoner, unless he preferred the better course of surrendering himself to the mercy of Arsaces. A short breathing-space was thus allowed the Romans, who took advantage of it to retire towards Carrhae, leaving behind them the greater part of their wounded, to the number of 4,000. A small body of horse reached Carrhae about midnight, and gave the commandant such information as led him to put his men under arms and issue forth to the succor of the proconsul. The Parthians, though the cries of the wounded made them well aware of the Roman retreat, adhered to their system of avoiding night combats, and attempted no pursuit till morning. Even then they allowed themselves to be delayed by comparatively trivial matters--the capture of the Roman camp, the massacre of the wounded, and the slaughter of the numerous stragglers scattered along the line of march--and made no haste to overtake the retreating army. The bulk of the troops were thus enabled to effect their retreat in safety to Carrhae, where, having the protection of walls, they were, at any rate for a time secure.