Fortunately for Ferdinand at this critical juncture, a Persian invasion and the Sultan’s domestic troubles created a diversion in his favour. In 1553 the Sultan, on account of the mutinous disposition of the army, which had been sent to defend Armenia against the Persians, was obliged to take command of it in person. The most notable event of the campaign was the tragical end of Mustapha, Solyman’s eldest and most promising son. The story of his cruel murder is narrated in pathetic words by our author in his first letter,[282] though he is mistaken in placing the scene of it near Amasia, as Eregli, in Karamania, where it really happened, is about 250 miles from that city. To appease the indignation of the soldiery at the death of their favourite, the Grand Vizier Roostem was deposed, and his office conferred on Achmet Pasha. Busbecq, during his visit to Amasia, in 1555, witnessed the conclusion of peace between the Sultan and the Shah. The Persian war relieved for a time the pressure on Hungary. Solyman granted a six months’ armistice, and Francis Zay and Antony Wranczy or Verantius, then Bishop of Fünfkirchen, and afterwards Bishop of Erlau, were sent as envoys to Constantinople.[283] They arrived in August. They were instructed to offer a tribute of 150,000 ducats for Hungary Proper, and 40,000 for Upper Hungary and Transylvania. The Viziers, however, told them that the abandonment of all claims to Transylvania was an indispensable preliminary to opening negotiations. Malvezzi was accordingly released, and sent to Vienna to receive further instructions from Ferdinand; and it was arranged that the peace should be prolonged for five years, and that on account of the loss of territory Ferdinand had sustained in Hungary the annual present or tribute should be reduced to 15,000 ducats. The peace was not to be ratified till Malvezzi’s return, but the truce was prolonged in the meanwhile. In May, 1554, Malvezzi was ordered to return, but he was prevented by illness, and Busbecq was sent in his stead.[284] He arrived at Constantinople on January 20, 1555, and proceeded in March, with Verantius and Zay, to the Sultan’s headquarters at Amasia. They brought him a present of gilded cups, and 10,000 ducats as tribute for Transylvania. They complained of the numerous breaches of the armistice on the part of the Turks, but, although they promised 80,000 ducats to the Sultan and large sums to the chief viziers, they could only obtain an extension of the armistice for six months, and a letter from Solyman to Ferdinand, with which Busbecq was sent to Vienna. On September 28, 1555, Achmet was executed, and Roostem reappointed Grand Vizier.[285]