Following the defection of Syracuse, several small Carthaginian dependencies switched to the Romans. Akragas, a port city halfway along the south coast of Sicily, was chosen by the Carthaginians as their strategic centre. The Romans marched on it in 262 BCE and besieged it. The Romans had an inadequate supply system, partly because the Carthaginian naval supremacy prevented them from shipping supplies by sea, and they were not in any case accustomed to feeding an army as large as 40,000 men. At harvest time most of the army was dispersed over a wide area to harvest the crops and to forage. The Carthaginians, commanded by Hannibal Gisco, sortied in force, taking the Romans by surprise and penetrating their camp; the Romans rallied and routed the Carthaginians; after this experience both sides were more guarded.