From a strategical point of view, it was of inestimable advantage that the capital and military centre of the Empire should be within striking distance of the route taken by the nomad populations of the East as they pressed towards the West, at the head of the Euxine. The Scythians, the Goths, and the Sarmatæ had all crossed that great region; the Huns were to cross it in the coming centuries. Placed on shipboard at Constantinople, the legions of the Empire could be swiftly conveyed into the Euxine, and could penetrate up the Danube, Tanais, or Borysthenes to confront the invaders where the danger threatened most. The story of how Constantine marked out the boundaries of his new capital is well known. Not content with the narrow limits of the ancient city—which included little more than the district now known as Seraglio Point—Constantine crossed the old boundary, spear in hand, and walked with his attendants along the shores of the Propontis, tracing the line as he went. His companions expressed astonishment that he continued so far afield, and respectfully drew the Emperor’s attention to the enormous circuit which the walls would have to enclose. Constantine rebuked them. “I shall still advance,” he said, “until He, the invisible guide who marches before me, thinks it right to stop.” The legend is first found in Philostorgius, and it is not of much importance. But Constantine, as usual, took care to foster the belief that his will was God’s will, even in the matter of founding Constantinople, and that he had but obeyed the clearly expressed command of Heaven. In one of his edicts he incidentally refers to Constantinople as the city which he founded in obedience to the mandate of God (_Jubente Deo_). It is a phrase which has meant much or little according to the character of the kings who have employed it. With Constantine it meant much, and, above all, he wished it to mean much to his subjects.