The Battle of Pharsalus between Caesar and Pompey began with the infantry of both sides hurling their pila at one another before charging, gladii drawn. However, the critical role of the pilum in this battle was still yet to arrive.
On Caesar's right flank, his heavily outnumbered cavalry were promptly being overwhelmed; squadrons of the Republican cavalry were looking to commence flanking manoeuvres. It was at this point that, either by prior design or simply through pressure being 45), Caesar had given specific instructions for these cohorts not to hurl their as they advanced, but rather, benefitting from their reach, to use their as thrusting weapons, aiming at the eyes and faces of the advancing cavalry. Caesar's reading of the situation was so precise that not only did the Republican cavalry fall into confusion and flee, abandoning their supporting archers and slingers to face the onslaught of the Julian cohorts, but it allowed the cohorts to launch a devastating flanking attack on the now exposed left flank of Pompey's forces. It is generally assumed that the major function of the was to discharge a volley to either disrupt or weaken the enemy front ranks prior to engagement. However, this was no mere javelin. A consisted of a long iron shank, attached to a wooden shaft of either hazel or ash by means of either a socketed or tanged hafting of the weapon. Polybius (6.26) provides us with the notion that there were two different weight-based varieties of , and experiments with reconstructed weapons have demonstrated that the lighter variety, sometimes referred to as a , probably averaged around 40 m in casting distance, whilst the heavier variety probably averaged around 25 m, though they could potentially reach 40 m. Earlier examples, from when the Romans first adopted the in the mid to late third century BC, tended to have the iron shank topped by a barbed spear-head. However, this soon evolved into a smaller, pyramidal head, which was typical by the late RepublicAs this pyramidal design had greater ability to punch through both shields and armour, this adaptation may reflect a specific need in weaponry as the Romans found themselves increasingly fighting civil wars rather than against less well-armoured foes such as the Samnites or Iberians, from whom the was most likely originally adopted.
