Austria--_Oesterreich_--is the ancient Eastmark or frontier province, the outpost of Carlovingian power against the tribes of the east, then of the mediaeval German Empire against Slav and Magyar. Under the House of Habsburg, which first rose to greatness on the ruins of a Greater Bohemia, Austria grew steadily stronger as a distinct unit. Two famous mottoes sum up the policy of that dynasty in the earlier centuries of its existence. _Austriae est Imperare Orbi Universo_ (Austria's it is to Rule the Universe) ran the device of that canny Frederick III., who, amid much adversity, laid the plans which prompted an equally striking epigram about his son and successor Maximilian, the "Last of the Knights"--_Bella gerant alii, tu, felix Austria, nube_ (Let others wage war; do thou marry, O fortunate Austria!). There were three great stages in Habsburg marriage policy. In 1479 Maximilian married the heiress of Charles the Bold, thus acquiring the priceless dowry of the Low Countries (what are now Belgium and Holland). In 1506 his son Philip added the crown of Spain and the Indies by his marriage with the heiress of Ferdinand and Isabella. In 1526, when the battle of Mohács placed Hungary at the mercy of the Turks, Maximilian's grandson Ferdinand, in his wife's name, united Bohemia, Hungary, and Croatia with the Austrian duchies. Henceforth for over two centuries Austria and Habsburg became the bulwark of Christendom against the Turks; though delayed by wars of religion and by the excesses of religious bigotry, they yet never lost sight of the final goal. Twice--at the beginning and at the end of this period, in 1527 and 1683--the Turks were before the very walls of Vienna, but the second of these occasions represents their final effort. In the closing years of the seventeenth and the first two decades of the eighteenth centuries the tide finally rolled back against them. Foremost among the victors stands out the great name of Prince Eugene, comrade-in-arms of our own Marlborough, whose song, "Prinz Eugen, der edle Ritter" (Prince Eugene, the noble Knight), has been sung in July and August 1914 on the streets of Vienna, just as "Marlbrook s'en va-t-en guerre" might be sung by our Belgian allies. The peace of 1718 represents Habsburg's farthest advance southwards; Belgrade and half of present-day Serbia owned allegiance to Vienna. Then came the check of 1739, when these conquests were restored to the Sultan. Due merely to incompetent generals, it need not have been permanent, had not Frederick the Great created a diversion from the north. By the time that the War of Austrian Succession and the Seven Years' War were over, that expansion southwards which had seemed so certain was irrevocably postponed. The organisation of fresh "Military Frontiers," the colonisation of waste lands in South Hungary--all was admirable so far as it went, but was already a defensive rather than an offensive measure. Meanwhile a formidable rival