And fifthly, that when our enemies have certain intelligence of our power and intentions we should beware much of invading their land, for a Captain's chief duty as regardeth his enemy is to conceal from them his force; and the contrary leadeth only to his own destruction and that of his men. And so Hannibal ever ordained his ambushes with such skill that his foes might never think his strength to be greater than it appeared for the moment.[N89] Sixthly, that we should take much care not to be discovered on a coast where we would make an inroad. And experience showeth examples of this every day to those who keep armed ships on the sea. And greatly do I marvel that Gonçallo de Sintra, a man who had ofttimes sailed in ships of the Armada[N90] by his lord's command and had taken a part in very great actions, both on the coast of Granada and in Ceuta, was not more on his guard at such a time. And the seventh conclusion I draw from the above event is that no man who cannot swim should cross rising water in a hostile country, except at the time for him to find that it hath ebbed away on his return. Such then are the matters I have had to write for your warning, and henceforth I will take up again the thread of my narrative. CHAPTER XXIX. How Antam Gonçalvez and Gomez Pirez and Diego Affonso went to the Rio d'Ouro. In that year the Infant bade Antam Gonçalvez, that noble knight of whom we have already spoken, to sail in one caravel and Gomez Pirez, master of the Royal Galley in another: and this man went by command of the Infant Don Pedro, who at that time governed the kingdom in the name of the King. And at the same time there was another caravel with them, in which sailed one Diego Affonso, a servant of the Infant Don Henry: and all these commanders went jointly to see if they could bring the Moors of that part to treat of merchandise. And they had much talk with them and obtained great sureties by means of the Moors whom the Infant sent there to see if with the aforesaid pretence they could guide them into the way of salvation. But they were not able to accomplish aught or do business with them, except in the matter of one negro. And so they turned back without achieving any more; except that they brought with them one old Moor, who of his own free will wished to come and see the Infant, from whom he received great rewards, according to his quality, and who afterward sent him back to his own country. But I am not so much surprised at the coming of this man as of a squire who went with Antam Gonçalvez, called John Fernandez; who of his own free will decided to stay in that land of Guinea, only to see the country and bring the news of it to the Infant when he should chance to return. But of the travels of this squire and of his excellent qualities I leave the account to another place. CHAPTER XXX. How Nuno Tristam went to Tira, and of the Moors that he took captive there.