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.