The Peltastai Makedonikoi are an expensive assault infantry in Makedonian and Seleukid armies, an elite used as a mobile reserve to plug gaps where the fighting is thickest and to storm fortresses.
Hail, Basileu! These men are the Peltastai and among the elite of your army. Men in their prime and drawn from the upper echelons of society they have been fitted with fine armor, a sword, and javelins. They excel in assault where their javelins can scatter defenders from breaches in defenses made by your siege engines. In the open field, their equipment, lighter in comparison to the heavily armed Hypaspistai, makes them adept at flanking the enemy battle line or exploiting openings made by your other troops.
Historically the elite Peltastai Makedonikoi appear at some point during the late 3rd century as the guard of the Antigonid kings and later with the other Diadochoi. The precise moment is not known due to scarcity of information concerning period between the Battle of Ipsos and start of second Punic War. It is from both Polybios and inscriptions found in Makedonia that we learn of them; that they were among the most fit Makedones available to the king; and likely the sons of noble families. They were younger than 35 and so at the peak physical strength for the average man. Their role in war was similar to that of Hypaspistai in the army of Alexander the Great: assault of fortifications, supporting light troops in broken terrain, and performing special missions that required both skill and strength. In set battles they could be equipped with sarissai and fight with the phalanx positioned in the place of honor at the right wing close to the king. Commanders of the Peltastai were among the most important persons in kingdom, as evidenced by Antigonos Doson’s naming the contemporary commander of the unit, along with four others, as protector of a young Phillipos V.