Notwithstanding his illness, he continued to give directions, superintending the building of the city and the management of the fleet. His mind, however, was oppressed with the thought that, in consequence of the destruction of the fortress, he should be compelled to send back the ships empty, instead of laden with gold and spices, to the great disappointment of the sovereigns. Before dispatching them, therefore, he sent Ojeda, at the head of an expedition, to the Golden Mountains, to try and obtain some of the precious metal. Another young cavalier was also sent away on a similar expedition, and both returned with favourable reports as to the inexhaustible wealth of the district. Thus, with more satisfaction than he had expected, Columbus was able to send back the ships to Spain. He recommended various persons to the notice of the sovereigns, to whom he sent a petition for provisions, wine, medicine, clothing, arms, horses, to be dispatched to the colony with all speed. He sent also the men, women, and children taken in the Caribbean Islands, recommending that they should be carefully instructed in the Spanish language and the Christian faith. In his ignorant zeal for promulgating that faith, he proposed to establish an exchange of the cannibal pagans as slaves, against live stock to be furnished to the colony, fancying that these slaves would be thus converted to the Catholic faith. The sovereigns, however, did not agree with his ideas, but ordered that the Caribs should be converted like the rest of the islanders. The city of Isabella having made considerable progress, the church being open for service, Columbus prepared to lead an expedition to the mountains of Cibao. Jealousy of Columbus' superior merits and the rewards he had received had been for some time rankling in the hearts of some of his officers. As he was about to set off on his expedition, a mutiny was designed, but discovered before it broke out, and the leader, Bernal Diaz, was confined on board one of the ships, to be sent to Spain for trial. Columbus now commenced the proposed expedition, leaving his brother Don Diego in command of the city and the ships. He was well received by the natives wherever he went, and was fully satisfied that the region was prolific in gold. To secure it he built a fortress called Saint Thomas, to the command of which he appointed Pedro Margarite, and garrisoned it with fifty-six men.