On the last day of June 1668 the buccaneers arrived off the shore of Castilla del Oro. On sighting land their chief disclosed his intention of attacking by night Portobello, a town often visited by the wealthiest merchants of Panamá, whose ingots of gold were there exchanged for slaves or for the merchandise of Spain, and the point to which it will be remembered were forwarded, at certain periods of the year, the gold and silver of the Peruvian and Mexican mines. The place was then accounted one of the strongest of the Spanish fortresses in the western world; it was garrisoned by three hundred troops, contained four hundred citizens capable of bearing arms, and was guarded by strongly fortified castles, commanding the approaches by land and sea. Many hesitated to attack such a stronghold with a mere handful of men, but their commander spoke words of cheer,[XXVIII‑1] and stimulated by the promise of vast spoils all at last gave their consent. In the dusk of a summer evening the fleet anchored at Porto Ponto, thirty miles west of the town. Leaving a few men to guard their ships the buccaneers ascended a small river in boats or canoes, and landing about midnight marched at once to the attack. All the avenues of approach were well known to Morgan, and among his band was an Englishman, once a prisoner among the Spaniards, who now acted as guide. A castle named Triana, situated in the eastern suburb, was selected as the first point of assault. A sentinel posted at some distance from the fortress was seized and bound by a small party sent in advance, before he had time to fire his musket. Brought into Morgan's presence he was closely questioned, and frequently menaced with death if his answers should prove untrue.