The lack of manpower was a serious concern for many Hellenistic rulers. In fact, the disparity between the manpower reserves available to Rome and to any Hellenistic monarch had a profound influence on the way in which the opponents made war. Roman generals could more easily risk defeat in battle, while for Hellenistic generals, a defeat might cripple their manpower base for nearly a generation. Many states had to rely on mercenaries to bulk up their citizen forces: For example, the army of the Achaean League under Aratus of Sicyon was re-organized to contain a permanent corps of mercenaries that numbered 8,000 foot and 500 horse, compared with the corps of picked Achaean troops, which numbered only 3,000 foot and 500 horse.