To give greater security to the Spaniards, Cortés caused a strong fortress to be erected in a place since known as the _Matadero_.[167] It was provided with a dock-yard, and the brigantines which had served in the siege of Mexico were long preserved there as memorials of the Conquest. When the fortress was completed, the general, owing to the evil offices of Fonseca, found himself in want of artillery and ammunition for its defence. He supplied the former deficiency by causing cannon to be cast in his own founderies, made of the copper which was common in the country, and tin which he obtained with more difficulty from the mines of Tasco. By this means, and a contribution which he received from the shipping, he contrived to mount his walls with seventy pieces of ordnance. Stone balls, much used in that age, could easily be made; but for the manufacture of his powder, although there was nitre in abundance, he was obliged to seek the sulphur by a perilous expedition into the bowels of the great _volcan_.[168] Such were the resources displayed by Cortés, enabling him to supply every deficiency, and to triumph over every obstacle which the malice of his enemies had thrown in his path. The general’s next care was to provide a population for the capital. He invited the Spaniards thither by grants of lands and houses, while the Indians, with politic liberality, were permitted to live under their own chiefs as before, and to enjoy various immunities. With this encouragement, the Spanish quarter of the city in the neighborhood of the great square could boast in a few years two thousand families; while the Indian district of Tlatelolco included no less than thirty thousand.[169] The various trades and occupations were resumed; the canals were again covered with barges; two vast markets in the respective quarters of the capital displayed all the different products and manufactures of the surrounding country; and the city swarmed with a busy, industrious population, in which the white man and the Indian, the conqueror and the conquered, mingled together promiscuously in peaceful and picturesque confusion. Not twenty years had elapsed since the Conquest, when a missionary who visited it had the confidence, or the credulity, to assert that “Europe could not boast a single city so fair and opulent as Mexico.”[170]