Of all the Greeks, Alexander appeared to him the most illustrious; of all his predecessors on the imperial throne, Trajan and Marcus Aurelius were those whom he most wished to emulate.

But all these princes had either led or sent expeditions into the far East, and had aimed at uniting in one the fairest provinces of Europe and Asia.
Julian appears, from the first moment that he found himself peaceably established upon the throne, to have resolved on undertaking in person a great expedition against Sapor, with the object of avenging upon Persia the ravages and defeats of the last sixty years, or at any rate of obtaining such successes as might justify his assuming the title of "Persicus." Whether he really entertained any hope of rivalling Alexander, or supposed it possible that he should effect "the final conquest of Persia," may be doubted.

Acquainted, as he must have been, with the entire course of Roman warfare in these parts from the attack of Crassus to the last defeat of his own immediate predecessor, he can scarcely have regarded the subjugation of Persia as an easy matter, or have expected to do much more than strike terror into the "barbarians" of the East, or perhaps obtain from them the cession of another province.

The sensible officer, who, after accompanying him in his expedition, wrote the history of the campaign, regarded his actuating motives as the delight that he took in war, and the desire of a new title.

Confident in his own military talent, in his training, and in his power to inspire enthusiasm in an army, he no doubt looked to reap laurels sufficient to justify him in making his attack; but the wild schemes ascribed to him, the conquest of the Sassanian kingdom, and the subjugation of Hyrcania and India, are figments (probably) of the imagination of his historians.
Julian entered Constantinople on the 11th of December, A.D.