Once in possesion of this tract, Chosroes conceived that he might launch a fleet upon the Euxine, command its commerce, threaten or ravage its shores, and even sail against Constantinople and besiege the Roman emperor in his capital.

The Persian king therefore acceded to the request of the envoys, and, pretending to be called into Iberia by a threatened invasion of the Huns, led a large army to the Lazic border, was conducted into the heart of the country by the envoys, received the submission of Gubazes, the king, and then, pressing on to the coast, formed the siege of Petra, where the Roman forces were collected.

Petra offered a stout resistance, and repulsed more than one Persian assault; but it was impossible for the small garrison to cope with the numbers, the engineering skill, and the ardor of the assailants.

After the loss of their commandant, Johannes, and the fall of one of the principal towers, the soldiers capitulated; Petra was made over to the Persians, who restored and strengthened its defences, and Lazica became for the time a Persian province.
II.

The War in Mesopotamia .-- Belisarius, on reaching the eastern frontier, fixed his head-quarters at Daras, and, finding that the Persians had no intention of invading Syria or Roman Mesopotamia, resolved to lead his troops into the enemy's territory.