He was succeeded by Mohammed IV., a boy seven years of age, during whose minority confusion reigned supreme. His grandmother and mother contended for power, and Janissaries and Spahis fought over the dead bodies of viziers, murdered in rapid succession for the spoil, till they met, A. D. 1656, with a master in the energetic Mohammed Kinperli. Under his administration internal licence was repressed by measures of salutary severity, and when foreign war again broke out it was conducted by him in a manner which revived the terror of the Turkish name. This war had its origin in the troubles of Hungary and Transylvania. The Transylvanians, on the death of their sovereign George Rakoczy, second of that name, elected as his successor a distinguished leader of his army, John Kemeni, who entered into an alliance with the Emperor Leopold I. At the instigation, however, of the Turkish Vizier, a faction of Hungarian nobles set up a rival candidate, Michael Apafi. Kemeni was defeated and slain in the battle of Nagy Szollos, fought against a Turkish force in 1662. Apafi seized on the government, cancelled all the measures adopted by Kemeni, and in an assembly of the States outlawed the adherents of Austria. He failed, however, in all his attempts upon the places occupied by German garrisons, and the presence of a so-called auxiliary Turkish force was a scourge rather than a protection to the exhausted country. In 1663 Apafi was compelled to lead his forces in the train of the Vizier Achmed Kinperli, son of Mohammed, who was marching upon Hungary with the intention and expectation of annihilating the power of Austria. The advance of the Turks was so rapid and unimpeded that Vienna once more trembled at the prospect of a siege. The measures for defence, of destruction, and repair were, as usual in the moment of danger, commenced in haste, and prosecuted with more confusion than real despatch. The progress of the Turks was favoured by disputes between the civil and military authorities of Austria, and the Vizier was thus allowed, without opposition, to secure the open country of Transylvania, and to reduce the important fortress of Neuhaüsel. After these successes he marched with his main army on Raab, with the project of exciting alarm for the safety of Styria, and then of suddenly flinging himself upon Vienna. It was, however, the good fortune of the Emperor Leopold to possess at this period the services of the only great commander of the moment, Raymond, Count of Montecuculi, as general of his forces in Hungary. On the 1st of August, 1669, this leader overthrew the Turks, in numbers fourfold greater than his own, with the loss of 17,000 men and all their artillery, in the memorable battle of St. Gothard. The armistice of Basvar followed close upon this victory. Twenty years were specified for its duration, but the civil and religious troubles of Hungary, and the severities by which Leopold sought to suppress them, led to its earlier infraction.