The Lazic war, which commenced in consequence of this act of Justinian’s, continued almost without intermission for nine years—­from A.D. 549 to 557.  Its details are related at great length by Procopius and Agathias, who view the struggle as one which vitally concerned the interests of their country.  According to them, Chosroes was bent upon holding Lazica in order to construct at the mouth of the Phasis a great naval station and arsenal, from which his fleets might issue to command the commerce or ravage the shores of the Black Sea.  There is no doubt that the country was eminently fitted for such a purpose.  The soil is for the most part richly fertile; the hills are everywhere covered with forests of noble trees; the Rion (Phasis) is deep and broad towards its mouth; and there are other streams also which are navigable.  If Chosroes entertained the intentions ascribed to him, and had even begun the collection of timber for ship-building at Petra on the Euxine as early as A.D. 549, we cannot be surprised at the attitude assumed by Rome, or at her persistent efforts to recover possession of the Lazic territory.

The war was opened by an attack upon the great centre of the Persian power, Petra.  This place, which was strongly situated on a craggy rock projecting into the sea, had been carefully fortified by Justinian before Lazica passed into the possession of Chosroes, and had since received important additions to its defences at the hands of the Persians.  It was sufficiently provisioned, and was defended by a body of fifteen hundred men.  Dagisthseus, the Roman commander, besieged it with his entire force of eight thousand men, and succeeded by his constant attacks in reducing the garrison to little more than a fourth of its original number.  Baffled in one attempt to effect a breach by means of a mine, he had contrived to construct another, and might have withdrawn his props, destroyed the wall, and entered the place, had he not conceived the idea of bargaining with the emperor for a specific reward in case he effected the capture.  Whilst he waited for his messenger to bring a reply, the Persian general, Memeroes, forced the passes from Iberia into Lazica, and descended the valley of the Phasis with an army of 30,000 men.  Dagisthalus in alarm withdrew, and Petra was relieved and revictualled.  The walls were repaired hastily with sandbags, and the further defence was entrusted to a fresh garrison of 3000 picked soldiers.  Mermeroes then, finding it difficult to obtain supplies for his large army, retired into Persarmenia, leaving only five thousand Persians in the country besides the garrison of Petra.  This small force was soon afterwards surprised by the combined Romans and Lazi, who completely defeated it, destroying or making prisoners almost the entire number.