Carthage usually recruited foreigners to make up its army. Many were from North Africa, and are usually referred to as Libyans; the region provided two main types of cavalry: close-order shock cavalry (also known as "heavy cavalry") carrying spears; and light cavalry skirmishers from Numidia who threw javelins from a distance and avoided close combat. Iberia also provided experienced cavalry: unarmoured close-order troops referred to by the ancient historian Livy as "steady", meaning that they were accustomed to sustained hand-to-hand combat rather than hit and run tactics. Hannibal's cavalry contingent would have consisted almost entirely of these three types, but the numbers of each are not known. Most male Roman citizens were eligible for military service and would serve as infantry, with a better-off minority providing a cavalry component. Traditionally, when at war the Romans would raise two or more legions, each of 4,200 infantry and 300 cavalry. Approximately 1,200 of the infantry in each legion, poorer or younger men unable to afford the armour and equipment of a standard legionary, served as javelin-armed skirmishers, known as velites. They carried several javelins, which would be thrown from a distance, a short sword, and a shield. An army was usually formed by combining one or several Roman legions with the same number of similarly sized and equipped legions provided by their Latin allies; allied legions usually had a larger attached complement of cavalry than Roman ones. Scipio's army consisted of four legions, with approximately 16,000 infantry and 1,600 cavalry. A further 2,000 Gallic cavalry and many Gallic infantry were also serving with the Romans. Scipio led out all of his 3,600 cavalry and, anticipating that they would be outnumbered, supplemented them with a large but unknown number of the 4,500 or so available velites. Battle Neither the precise date nor the precise location of the battle are known: it took place in late November 218 BC on the flat country on the west bank of the Ticinus, not far from modern Pavia. The ancient historians Livy and Polybius both give accounts of the battle, which agree on the main events, but differ in some of the details. Formal battles were usually preceded by the two armies camping two to twelve kilometres (1–7 mi) apart for days or weeks; sometimes forming up in battle order each day. In such circumstances either commander could prevent a battle from occurring, and unless both commanders