Suddenly, tidings of a most alarming kind dispelled his pleasing visions, and roused him to renewed exertions.  Revolt, he found, had broken out everywhere in his rear.  At Seleucia, at Hatra, at Nisibis, at Edessa, the natives had flown to arms; his entire line of retreat was beset by foes, and he ran a risk of having his return cut off, and of perishing in the land which he had invaded.  Trajan had hastily to retrace his stops, and to send his generals in all directions to check the spread of insurrection.  Seleucia was recovered by Erucius Clarus and Julius Alexander, who punished its rebellion by delivering it to the flames.  Lucius Quietus retook Nisibis, and plundered and burnt Edessa.  Maximus, on the contrary, was defeated and slain by the rebels, who completely destroyed the Roman army under his orders.  Trajan, perceiving how slight his hold was upon the conquered populations, felt compelled to change his policy, and, as the only mode of pacifying, even temporarily, the growing discontent, instead of making Lower Mesopotamia into a Roman province, as he had made Armenia, Upper Mesopotamia, and Adiabene (or Assyria), he proceeded with much pomp and display to set up a native king.  The prince selected was a certain Parthamaspates, a member of the royal family of the Arsacidse, who had previously sided with Rome against the reigning monarch.  In a plain near Ctesiphon, where he had had his tribunal erected, Trajan, after a speech wherein he extolled the greatness of his own exploits, presented to the assembled Romans and natives this youth as King of Parthia, and with his own hand placed the diadem upon his brow.

Under cover of the popularity acquired by this act the aged Emperor now commenced his retreat.  The line of the Tigris was no doubt open to him, and along this he might have marched in peace to Upper Mesopotamia or Armenia; but either he preferred the direct route to Syria by way of Hatra and Singara, or the insult offered to the Roman name by the independent attitude which the people of the former place still maintained induced him to diverge from the general line of his course, and to enter the desert in order to chastise their presumption.  Hatra was a small town, but strongly fortified.  The inhabitants at this time belonged to that Arabian immigration which was always more and more encroaching upon Mesopotamia.  They were Parthian subjects, but appear to have had their own native kings.  On the approach of Trajan, nothing daunted, they closed their gates, and prepared themselves for resistance.  Though he battered down a portion of the wall, they repulsed all the attempts of his soldiers to enter through the breach, and when he himself came near to reconnoitre, they drove him off with their arrows.  His troops suffered from the heat, from the want of provisions and fodder, from the swarms of flies which disputed with them every morsel of their food and every drop of their drink, and finally from violent hail and thunderstorms.  Trajan was forced to withdraw after a time without effecting anything, and to own himself baffled and defeated by the garrison of a petty fortress.