4 _Shrinkage and Retreat_ The fringes of this vast empire, however, none too surely held, were already involving it in insoluble difficulties and imminent dangers. On the one hand, in Asia, it had been found impossible to establish military fiefs in Arabia, Kurdistan, or anywhere east of it, on the system which had secured the Osmanli tenure elsewhere. On the other hand, in Europe, as we have seen, the empire had a very unsatisfactory frontier, beyond which a strong people not only set limits to further progress but was prepared to dispute the ground already gained. In a treaty signed at Sitvatorok, in 1606, the Osmanli sultan was forced to acknowledge definitely the absolute and equal sovereignty of his northern neighbour, Austria; and although, less than a century later, Vienna would be attacked once more, there was never again to be serious prospect of an extension of the empire in the direction of central Europe. Moreover, however appearances might be maintained on the frontiers, the heart of the empire had begun patently to fail. The history of the next two centuries, the seventeenth and eighteenth, is one long record of praetorian tumults at home; and ever more rarely will these be compensated by military successes abroad. The first of these centuries had not half elapsed ere the Janissaries had taken the lives of two sultans, and brought the Grand Vizierate to such a perilous pass that no ordinary holder of it, unless backed by some very powerful Albanian or other tribal influence, could hope to save his credit or even his life. During this period indeed no Osmanli of the older stocks ever exercised real control of affairs. It was only among the more recently assimilated elements, such as the Albanian, the Slavonic, or the Greek, that men of the requisite character and vigour could be found. The rally which marked the latter half of the seventeenth century was entirely the work of Albanians or of other generals and admirals, none of whom had had a Moslem grandfather. Marked by the last Osmanli conquest made at the expense of Europe—that of Krete; by the definite subjugation of Wallachia; by the second siege of Vienna; by the recovery of the Morea from Venice; and finally by an honourable arrangement with Austria about the Danube frontier—it is all to be credited to the Kuprili ‘dynasty’ of Albanian viziers, which conspicuously outshone the contemporary sovereigns of the dynasty of Osman, the best of them, Mohammed IV, not excepted. It was, however, no more than a rally; for greater danger already threatened from another quarter. Agreement had not been reached with Austria at Carlowitz, in 1699, before a new and baleful planet swam into the Osmanli sky.