Plutarch wrote that Perseus did not realise what was going on because Aemilius remained in his position quietly, whereas Livy did not state this about Perseus and gave an account of Aemilius giving two battles to keep Perseus distracted from the covert operation. Both authors wrote that a Cretan deserter informed Perseus, who sent 2,000 Macedonians and 10,000 mercenaries to Pythium. In Plutarch's account they went to occupy the mountain passes. Livy's account implies that they were sent to the pass Nasica was to attack. He also wrote that the pass was guarded by 5,000 Macedonian troops. He added that Nasica said that the steep descent would have been so unguarded that it would have been taken without trouble had it not been for the deserter. Both authors noted that Polybius (in a lost part of book 29 of his Histories) stated that Nasica attacked when they were asleep but Nasica wrote (in the mentioned letter) that there was a tough fight, that he killed a Thracian mercenary who had engaged him and that their leader disgracefully threw away his armour and cloak and fled. The Romans pursued the enemy down to the plain.