Nor were these brave words a mere _brutum fulmen_. Simultaneously with the putting forth of such lofty pretensions the troops of the Persian monarch crossed the Tigris and spread themselves over the entire Roman province of Mesopotamia, which was rapidly overrun and offered scarcely any resistance. Severus learned at the same moment the demands of his adversary and the loss of one of his best provinces. He heard that his strong posts upon the Euphrates, the old defences of the empire in this quarter, were being attacked, and that Syria daily expected the passage of the invaders. The crisis was one requiring prompt action; but the weak and inexperienced youth was content to meet it with diplomacy, and, instead of sending an army to the East, despatched ambassadors to his rival with a letter. “Artaxerxes,” he said, “ought to confine himself to his own territories and not seek to revolutionize Asia; it was unsafe, on the strength of mere unsubstantial hopes, to commence a great war. Every one should be content with keeping what belonged to him. Artaxerxes would find war with Rome a very different thing from the contests in which he had been hitherto engaged with barbarous races like his own. He should call to mind the successes of Augustus and Trajan, and the trophies carried off from the East by Lucius Verus and by Septimius Severus.” The counsels of moderation have rarely much effect in restraining princely ambition. Artaxerxes replied by an embassy in which he ostentatiously displayed the wealth and magnificence of Persia; but, so far from making any deduction from his original demands, he now distinctly formulated them, and required their immediate acceptance. “Artaxerxes, the Great King,” he said, “ordered the Romans and their ruler to take their departure forthwith from Syria and the rest of Western Asia, and to allow the Persians to exercise dominion over Ionia and Caria and the other countries within the AEgean and the Euxine, since these countries belonged to Persia by right of inheritance.” A Roman emperor had seldom received such a message; and Alexander, mild and gentle as he was by nature, seems to have had his equanimity disturbed by the insolence of the mandate. Disregarding the sacredness of the ambassadorial character, he stripped the envoys of their splendid apparel, treated them as prisoners of war, and settled them as agricultural colonists in Phrygia. If we may believe Herodian, he even took credit to himself for sparing their lives, which he regarded as justly forfeit to the offended majesty of the empire.