Thus perished the last Saracen armament which ever seriously threatened the existence of the East-Roman Empire. It was perhaps the most formidable expedition that the Caliphs ever sent forth, far larger and better equipped than the predatory bands which had overrun Africa and Spain with such ease a few years before, or the army which Charles Martel faced at Poictiers a few years later. It was no mean achievement of Leo the Isaurian, that, ere yet firmly seated on his throne, and with all his Asiatic provinces already overrun by the enemy, he should beat off with ease such a mighty armament. His success must be ascribed primarily to his own courage, energy, and skill, next to the impregnable strength of the walls of Constantinople, and lastly, to the inexperience of the Arabs on the sea, which compelled them to use unwilling Christian seamen for their galleys, and prevented them from making any adequate use of their momentary naval predominance. The fleet of Moslemah seems to have been as useless and unwieldy as the fleet of Xerxes. But, however much he may have been helped by the faults of his enemy, Leo the Isaurian deserves the thanks of all future ages for staying the progress of the Saracen invader at a moment when there was no other power in eastern Europe which could have for a moment held back the advancing Moslem. If Constantinople had fallen, it is absolutely certain that the barbarous pagan tribes who occupied all eastern and central Europe would have become the subjects of the Caliph, and the votaries of Islam. There was no capacity for prolonged resistance in the Bulgarian, Avar, or Slav; and if the East-Roman Empire had fallen, the wave of Saracen invasion would have swept all before it up to the borders of Austrasia. Whether the Franks could have stood firm if attacked on the east as well as on the south is very doubtful. It is, therefore, fair to ascribe to Leo the Isaurian an even greater share in the salvation of Europe from the Moslem peril than is given to Charles Martel. After the failure of Moslemah the victorious Leo had a breathing time granted him, in which to reorganise the shattered realm that had been left him by his predecessor. Although the Saracen war still went on, and border raids never ceased till the very end of his reign, yet there was no very serious danger in these latter bickerings, and Leo was able to turn his attention to the internal affairs of the empire, without the fear of having at any moment a dangerous invasion launched against him from beyond the Taurus.