This ruinous draining of the vital power of the empire only began to be seriously felt after 540, when, for the first time, Justinian was compelled to wage war at once in East and West, and yet refused to slacken from his building. The Gothic war—contrary to all probability and expectation—was still destined to run on for thirteen years more; the Persian lasted for sixteen, and, when they were over, the emperor and the empire alike were but the shadow of their former selves: they were unconquered, but drained of all their strength and marrow. [Illustration: THE PERSO-ROMAN FRONTIER UNDER JUSTINIAN. ] We have already mentioned that the young king Chosroes of Persia, stirred up by the embassy of Witiges, and dreading lest the power which had subdued Carthage and Rome should ere long stretch out its hand to Ctesiphon, had found a _casus belli_, and crossed the Mesopotamian frontier. Some blood-feuds between Arab hordes respectively subject to Persia and Constantinople, and a dispute about the suzerainty of some tribes in the Armenian highlands formed a good enough excuse for renewing the war at a moment when Justinian’s best general and 50,000 of the flower of his troops were absent in Italy and Africa. [Sidenote: Second Persian war, 540-545.] In the spring of 540, at the very moment when Belisarius was reducing Ravenna, Chosroes marched up the Euphrates, leaving the frontier fortresses of Daras and Edessa on his flank, and launched a sudden attack on north Syria. He had been expected not there but in Mesopotamia, and all preparations for defence were out of gear. Before any resistance was organised Chosroes had crossed the Euphrates, sacked Beroea, and ransomed Hierapolis for 2000. lbs. of gold. But it was at Antioch, the third city of the Roman Empire, and the seat of the Praetorian Prefect of the East that the Persian monarch was aiming. It was more than two centuries and a half since the city of the Orontes had seen a foreign foe, and its walls were old and dilapidated. A garrison of 6000 men was thrown in, and the Blues and Greens of the city armed themselves to guard the ramparts. [Sidenote: Sack of Antioch, 540.] But there was no Roman army in the field to protect the city from the approach of the Persian: Buzes, the general of the East, refused to risk his small army in a general engagement, and had retired no one knew whither. The siege of Antioch was short, for the defence was ill-managed: the garrison cut its way out when the walls were forced, but the town, with all its wealth, and a great number of its inhabitants who had not found time to fly, became the prize of Chosroes. The Persian plundered the churches, burnt the private houses, and drove away a herd of captives, whom he took to his home, and established in a new city near Ctesiphon, which he called Chosroantiocheia.