Cavalry and chariots against infantry

[Michael Kerr]

Hi, in regards to Roman Infantry against cavalry charges I have 2 questions. Were pila effective as a defence against cavalry? Were they thrown in a volley when the cavalry got close or did the romans use them as spears like the Greeks in their phalanxes? To my thinking pila would be too short and wouldn't project too far beyond the shield to be a deterrent against cavalry so I assume the romans would have packed their legions with missile troops and steady nerve by the legionaries would be crucial as timing of volleys was important.
Just one other question regarding cavalry vs infantry in ancient warfare. Were cavalry charges against ancient infantry a case of who blinks first? If the infantry blinks and attempts to flee then the horses ride into the gaps to inflict more damage to the remaining infantry or if the horses blink when seeing an unwavering line of spears and attempt to turn to avoid them at the last possible moment. I can see that people all have strong feelings about this by the number of posts on this thread but in regards to problems when comparing similar tactics from different eras I was thinking about the infantry square which in Napoleonic times was effective against cavalry eg. the British at Waterloo but in Roman times at the battle of Carrhae the infantry squares were inneffective against Parthian horse archers.