During Sapor’s youth the mighty change had taken place by which Constantine procured for Christianity the victory over paganism in the Roman Empire. The Christians in the Persian Empire immediately recognised in Rome the Christian state _par excellence_, and were strongly disposed in its favour. When Sapor went to war with the Romans (337 or 338) they openly displayed their own sentiments; at least a homily of Aphraates, a Syrian bishop in the Persian Empire, written about this time, speaks on the subject in no ambiguous tone. In addition to this, Simon, bishop of the capital, indulged in such defiant utterances as no oriental monarch was likely to let pass, least of all a young and energetic sovereign like Sapor II. It was the signal for conflict, and a frightful persecution of the Christians began almost simultaneously with the Roman War (339-40). We have an animated picture of these events in the Syrian _Acts of the Martyrs_, which throw much light on other things and persons in the empire. The king was not actuated by religious fanaticism. The Jews were as obnoxious to his priests as the Christians, but he left them unmolested. Even in the _Acts of the Martyrs_ he repeatedly appears as a man wholly without bias in purely religious matters. But, like Diocletian, he wished to annihilate that state within the state--the organisation of the church; and he therefore destroyed church buildings and took the most vigorous measures against both the superior and the inferior clergy. A NEW WAR WITH ROME [Sidenote: [337-363 A.D.]] According to Roman assertions, the Persians began the war by an invasion of Mesopotamia. Constantine died before he could take the field against them (the 22nd of May, 337). But the king’s great preparations date from the year which begins with the autumn of 337. On the first and longer half of the war, which lasted with many vicissitudes and long pauses for twenty-five years, our information is but scanty. On parts of the second, on the contrary, we possess very full reports by contemporaries and even eye-witnesses. The king’s object was to deprive the Romans of their possessions on the upper Tigris, where it must have been exceedingly inconvenient for the Persians to have them on account of their nearness to Ctesiphon. Above all, he aimed at taking the strong fortress of Nisibis; and he further desired to bring Armenia, that old apple of discord between the Eastern and Western empires, into subjection to himself once more. Three times he closely besieged Nisibis (in the years 338, 346, and 350), but in vain. Sieges, on the whole, play a very great part in this war.