In 1520 an earthquake, far more severe than any shock hitherto experienced, occurred, and did damage valued at 100,000 ducats in the town, and 50,000 in the neighbourhood. The Monte Bergato seemed about to fall and overwhelm Ragusa, “but the city was saved through the intervention of the San Biagio and of the Blessed Virgin.”[431] Twenty persons were killed and many injured. The little chapel of San Salvatore was erected as a votive offering to express the gratitude of the citizens at the salvation of the town. Six years later a terrible pestilence broke out, and wrought fearful havoc in spite of the precautions taken to isolate the sick. The death-rate was about 100 a day,[432] and in all 164 nobles, 184 monks and nuns, and 20,000 other citizens died. The city was abandoned by all save a guard of soldiers and the crews of two galleys remaining in the port. The Senate held its sittings at Gravosa, and the population only returned after twenty months.[433] Shortly after a pirate fleet of twenty-four sail appeared off Molonta threatening the town. But in spite of the disorganisation caused by the plague the Government was able to fit out a fleet of ten large ships, two galleys, one barque, and eighteen brigantines, under the command of Marino Zamagna, who, with the help of two Venetian ships, drove the pirates out of the Adriatic. The year 1526 was a momentous one for Christendom. The Turkish wars with Hungary had been going on intermittently for many years, now one side gaining the advantage now the other, but no decisive operations had taken place recently. In Bosnia, the fortress of Jajce became the centre of the fighting, and was again and again besieged by the Turks, who were again and again repulsed with heavy loss. Besides Jajce, the Hungarians held a strip of territory south of the Save, including the fortresses of Zvornik, Szabács, and Belgrad. When Suleiman the Magnificent ascended the throne of Othman in 1520, he determined to seize these strongholds so as to open the way into Hungary. He collected a powerful army, and led it in person into the Banate. Szabács was the first to fall, in 1521; Semlin, Slankamen, Mitrović, Zvornik, Tešanj, and Sokol were next captured, and after a long siege Belgrad was taken by treachery. But the attack on Jajce, which was defended by the gallant Peter Keglević, failed completely. A second attack on Jajce was equally unsuccessful, owing to the arrival of a Croatian force under Frangipani. In 1526 Suleiman again invaded Hungary, and on August 29 the great battle of Mohács was fought, in which the Hungarians were totally defeated and 20,000 of them, including their King, killed. This disaster marks the end of Hungary for the time being. The Sultan conquered all that remained of Bosnia, including Jajce, in 1528, as well as a large part of Croatia and southern Hungary.