, 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a mine, he had contrived to construct another, and might have withdrawn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