In his description of the Battle of Cynoscephalae, Polybius informs us of a unit he calls Peltasts, which he clearly places among the phalanx. Although the Macedonian shield could be characterized as a pelta (targe), the term peltast was usually used to describe a type of shielded, skirmishing, light infantry. It has been suggested that these peltasts were indeed a picked corps, much like Alexander's hypaspists, 'an infantry force...which fought beside the phalanx in battle, but at other times employed for ambushes, forced marches and special expeditions'. The Peltasts were sent on special missions, such as an ambush in Lycestis or being used as shock troops in the storming of Cephallenia. The elite of the Peltast corps was known as the 'Agema'.