When it seemed that he could not stop the fighting, Aemilius decided to turn an accident into an opportunity and brought his forces out of the camp. Nasica told him that Perseus was advancing. The Thracians, flanked by light infantry, formed the first line. Next to them there were mercenaries of various nationalities. The Leucaspides (phalanx with white shields) formed the middle. In the rear there were the Chalcaspides (phalanx with bronze shields), flanked on the right wing by another phalanx. These two were the main strength of the army. There were also targeteers, who were midway between the phalanx and the light infantry. They had spikes like those of the phalanx but wore light armour. They stood in front of the wings. This army had been so swift that those who were first killed fell close to the Roman camp. A unit of Paelignans from central Italy and those at their rear were routed and the rest of the soldiers in that part of the battlefield withdrew to a hill. Elsewhere the Roman forces were hesitant to confront the long spears of the Macedonian phalanx. When the Romans tried to push aside their stretched out spears, the Macedonians held them firmly and transfixed the enemy, piercing both their shields and armour. The spears formed an insurmountable barrier.