In the ensuing year, A.D. 550, the Persians took the field under a fresh general, Chorianes, who brought with him a considerable army, composed of Persians and Alans.  The allied Romans and Lazi, under Dagisthseus and Gubazes, gave battle to this new foe on the banks of the Hippis (the Tschenikal?); and though the Lazi, who had insisted on taking the lead and fighting separately, were at the first encounter routed by the Persian horse, yet in the end Roman discipline and stubbornness triumphed.  Their solid line of footmen, bristling with spears, offered an impervious barrier to the cavalry of the enemy, which did not dare to charge, but had recourse to volleys of missiles.  The Romans responded with the same; and the battle raged for a while on something like even terms, the superior rapidity of the Asiatics being counterbalanced by the better protection which their shields gave to the Europeans, until at last, by a stroke of fortune, Rome obtained the victory.  A chance arrow killed Chorianes, and his army instantly fled.  There was a short struggle at the Persian camp; but the Romans and Lazi captured it.  Most of the Persians were here put to the sword; the few who escaped quitted Lazica and returned to their own country.

Soon afterwards Dagisthseus was superseded by Bessas, and the siege of Petra was recommenced.  The strength of the place had been considerably increased since the former attack upon it.  A new wall of great height and solidity had been built upon a framework of wood in the place which Dagisthaeus had so nearly breached; the Roman mines had been filled up with gravel; arms, offensive and defensive, had been collected in extraordinary abundance; a stock of flour and of salted meat had been laid in sufficient to support the garrison of 3000 men for five years; and a store of vinegar, and of the pulse from which it was made, had likewise been accumulated.  The Roman general began by attempting to repeat the device of his predecessor, attacking the defences in the same place and by the same means; but, just as his mine was completed, the new wall with its framework of wood sank quietly into the excavation, without suffering any disturbance of its parts, while enough of it still remained above the surface to offer an effectual bar to the assailants.  It seemed hopeless to recommence the mine in this place, and elsewhere the nature of the ground made mining impossible; some other mode of attack had therefore to be adopted, or the siege must have been abandoned.  Rome generally took towns by the battering-ram; but the engines in use were of such heavy construction that they could not be dragged up an ascent like that upon which Petra stood.  Bessas was in extreme perplexity, when some Hunnic allies, who happened to be in his camp, suggested a mode of constructing a ram, as effective as the ordinary one, which should nevertheless be so light that it could be carried on the shoulders of forty men.  Three such machines were quickly made; and under their blows the wall