X. While Sertorius was considering where he should betake himself to, the Lusitani sent ambassadors to invite him to be their leader; for they were much in want of a commander of great reputation and experience, to oppose the formidable power of the Romans, and Sertorius was the only man whom they would trust, as they knew his character from those who had been about him. Now it is said that Sertorius was a man who never yielded either to pleasure or to fear, and while he was naturally unmoved by danger, he could bear prosperity with moderation; in the open field he was equal to any general of his time in enterprise, and as to all military matters that required stealthy manœuvres, the taking advantage of strong positions and rapid movements, and also craft and deception, he was in the moment of need most cunning in device. In rewarding courage he was bountiful, and in punishing for offences he was merciful. And yet, in the last part of his life, his cruel and vindictive treatment of the hostages may be alleged as a proof that his temper was not naturally humane, but that he put on the appearance of mildness through calculation and as a matter of necessity, But it is my opinion that no fortune can ever change to the opposite character a virtue which is genuine and founded on principle; still it is not impossible that good intentions and good natural dispositions, when impaired by great misfortunes[129] contrary to desert, may together with the dæmon change their habit; and this I think was the case with Sertorius when fortune began to fail him; for as his circumstances became unfavourable, he became harsh to those who had done him wrong. XI. However, he then set sail from Libya, at the invitation of the Lusitanians,[130] and got them into fighting condition, being immediately made commander with full powers, and he subjected the neighbouring parts of Iberia, most of which, indeed, voluntarily joined him, chiefly by reason of his mild treatment and his activity; but in some cases he availed himself of cunning to beguile and win over the people, the chief of which was in the affair of the deer, which was after this fashion: