system
You are a chatbot acting as a human, specialising in Summarize. Give a response that a human will want to hear.
human
Summarize the use of the pilum in the battle of Pharsalus

In 48 BC, Pompey the Great attempted to use it against Julius Caesar at the Battle of Pharsalus, in what was to be the decisive battle of the Great Roman Civil War. Caesar countered this by ambushing Pompey's "hammer" element with a hidden fourth line of infantry;[5] Pompey's infantry was to be the anvil while his cavalry 'hammer' encircled Caesar's left flank. There was significant distance between the two armies, according to Caesar.[6]
As the infantry of Caesar advanced, Pompey ordered his men not to charge, but to wait until Caesar's legions came into close quarters; Pompey's adviser Gaius Triarius believed that Caesar's infantry would be fatigued and fall into disorder if they were forced to cover twice the expected distance of a battle march. Also, stationary troops were expected to be able to defend better against pila throws.[7] Seeing that Pompey's army was not advancing, Caesar's infantry under Mark Antony and Gnaeus Domitius Calvinus started the advance. As Caesar's men neared throwing distance, without orders, they stopped to rest and regroup before continuing the charge;[8] Pompey's right and centre line held as the two armies collided. Caesar countered this by positioning the reserves of his 4th line to intercept the attacking cavalry.
As Pompey's infantry fought, Labienus ordered the Pompeian cavalry on his left flank to attack Caesar's cavalry; as expected they successfully pushed back Caesar's cavalry. Caesar then revealed his hidden fourth line of infantry and surprised Pompey's cavalry charge; Caesar's men were ordered to leap up and use their pila to thrust at Pompey's cavalry instead of throwing them. Pompey's cavalry panicked and suffered hundreds of casualties, as Caesar's cavalry came about[9] and charged after them. After failing to reform, the rest of the Pompey's cavalry retreated to the hills, leaving the left wing of Pompey's legions exposed to the hidden troops as Caesar's cavalry wheeled around their flank. Caesar then ordered in his third line, containing his most battle-hardened veterans, to attack. This broke Pompey's left wing troops, who fled the battlefield.[10]
gpt
Pompey the Great expected the pila employed by Julius Caesar’s troops to be used as throwing weapons. He consequently ordered his troops to refrain from charging, in part to better defend against them. The hidden fourth line of infantry Caesar employed against Pompey’s cavalry did not throw their pila, but instead used them as thrusting weapons.