for some of the necessaries and all the conveniences of life, and capable of exporting nothing but timber, slaves, and skins.  It might have been expected, under such circumstances, that the burden of the protectorate would have been refused; but there was an advantage, apparent or real, in the position of the country, discovered by the sagacity of Chosroes or suggested to him by the interested zeal of the envoys, which made its possession seem to the Persian king a matter of the highest importance, and induced him to accept the offer made him without a moment’s delay.  Lazica, the ancient Colchis and the modern Mingrelia and Imeritia, bordered upon the Black Sea, which the Persian dominions did not as yet touch.  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.  As his forces were weak in numbers, ill-armed, and ill-supplied, he could scarcely hope to accomplish any great enterprise; but it was important to recover the Roman prestige after the occurrences of the preceding year, and to show that Rome was willing to encounter in the open field any force that the Persians could bring against her.  He therefore crossed the frontier and advanced in the direction of Nisibis, less with the intention of attacking the town than of distinctly offering battle to the troops collected within it.  His scheme succeeded; a small force, which he threw out in advance, drew the enemy from the walls; and their pursuit of this detachment brought them into contact with the main army of Belisarius, which repulsed them and sent them flying into the town.  Having thus established his superiority in the field, the Roman general, though he could not attack Nisibis with any prospect of success, was able to adopt other