For the traveller who from the Tower of St. Stephen's, in the centre of the old-town of Vienna, looks down upon the places made remarkable by great historic actions in the valley of the Danube, has his eye turned first northward and eastward upon the Marchfeld. There, he is told, are Aspern and Essling, where the Archduke Charles beat Napoleon in 1809. There is the island of Lobau, where Napoleon repaired his forces, and whence he issued to fight yonder the great and terrible conflict of Wagram. The scene, not of a greater slaughter, not of a more obstinately contested fight, than Wagram, but the scene of a battle more momentous in its consequences, lies upon the other side. Among the vineyards, villages, and chateaux which cover the lower slopes of the Wiener Wald, among the suburbs of Nussdorf and of Hernals, Charles of Lorraine and John Sobieski smote the Turkish armies in 1683. There at one blow they frustrated the last great Mohammedan aggression against Christendom, and set free the minds and arms of the Germans to combine against French ambition upon their western frontier. The victory was one of those decisive events which complete long pending revolutions, and inaugurate new political conditions in Europe. The treaties of Nimuegen in 1678-79 had marked a pause in a general European contest. France and the Empire, Holland, Spain, Sweden, Brandenberg, all retired from their active conflicts, to plot and strive in secret, till an advantageous opening for war should again present itself. Poland and the Porte had a little earlier concluded their strife by the peace of Zurawna. But in the general breathing-time the eyes of all were turned with anxiety upon Eastern Europe. So much of Hungary as was not in the hands of the Sultan was in insurrection against the Emperor. The insolence of the Turks, and their support to the insurgents, were continually becoming greater. The whole East resounded with warlike preparations, and it was without doubt evident that a great enterprise was being prepared which might make the reign of Mahomet IV. as illustrious for Islam, as calamitous for Christendom, as that of Mahomet II. had been. Rome, Venice, Vienna, were the three capitals in more immediate danger, but the whole continent was interested, and all other designs were necessarily suspended till it became clearer where this storm would fall, and what resistance could be made to it. For, two hundred years ago, the Ottoman Empire still stood high among the greatest of European powers. Spain ruled over wider territories; but the dominions of Spain were scattered over the Old and New Worlds, and her European lands, in the Netherlands and in Italy, were divided from her by the sea, or isolated by the interposition of the frontiers of powerful and often hostile neighbours.