In the winter of 1530 Ferdinand’s troops besieged Buda unsuccessfully. In the campaign of 1532 Charles V. came with the forces of the Empire to the assistance of his brother, and Styria and Austria were the seat of war. The Sultan was detained for three weeks before the little town of Güns by the gallantry of the commander Jurischitz, who at last surrendered on honourable terms.[275] The delay, however, prevented the Sultan from accomplishing anything considerable, though his army ravaged Styria and Austria, and penetrated as far as Gratz and Linz. In June 1533 peace was concluded between Ferdinand and Solyman on the basis of Ferdinand’s retaining what he actually held in Hungary, the Sultan reserving to himself the ratification of any arrangements that Ferdinand and Zapolya might make between themselves. For some years afterwards Solyman’s attention was devoted to his wars with Persia, and no invasion of Hungary on a large scale occurred; but, notwithstanding the peace, the Pashas of Bosnia and the adjoining districts continued their inroads. To check these incursions Ferdinand, in 1537, assembled at Kaproncza, on the Drave, an army of 16,000 foot and 8,000 horse, under the supreme command of Katzianer. He advanced on Essek, intending to besiege it, but was surrounded by clouds of light cavalry, who cut off his supplies and forced him to retreat. After losing his siege-guns at the passage of the Vouka, he encountered the enemy on December 1, and, after an unsuccessful engagement, fled in the night with some of the other generals. The troops that were left were cut to pieces the next day with their gallant commander, Lodron.[276] Katzianer was accused of causing the disaster by his cowardice, and was thrown into prison at Vienna. He escaped by bribing his gaolers, and fled to one of his castles in Croatia, where he entered into negotiations with the Turks, promising to betray the strong fortress of Kosthanitza. However, his treasonable designs were cut short; Count Nicholas Zriny, during an interview with him at one of his castles, treacherously stabbed him, and despatched him with the assistance of his servants. His body was flung from a window into the castle ditch, and his head was sent to Vienna. In 1538, under the mediation of Charles V., the treaty of Gross Wardein was concluded between Zapolya and Ferdinand. Zapolya was to retain the title of King during his life with Transylvania and the part of Hungary which was then in his actual possession, on his death his male issue was to succeed to Transylvania only, and by the same treaty both parties united in a league for mutual defence against the Turks. Zapolya had then neither wife nor child; but he immediately afterwards married Isabella, the King of Poland’s daughter, and, dying in July 1540, left by her a son—John Sigismund—who was born a fortnight before his father’s death.