M.G. parrskool kicked it off with this question:
"Here's the thing...........
A unit of Celtish light Cav. attacked my unit of early imperial romans and lost the fight. The romans followed up to maintain contact. I was a bit disturbed by this as I did not think that infantry usually charged cav."
After several days of back and forth and rules discussion, Alex Elstone's first reply turns out to have hit the mark:
"Well, the Romans followed up to maintain contact. This isn't counted as a charge but a continuation of the combat. Look at it as if the cavalry were surrounded and couldn't quite extricate themselves from the combat. The reason why it looks like the Romans charged is all due to the restrictions of model unit depiction. Everything is depicted in regimented squares, whereas in a real combat men would engage in a swirling melee. The cavalrymen would most likely have lost their bearings, momentarily and unable to escape or that the Romans were very quick to cut off their retreat.
Ordinarily, the infantry cannot charge cavalry. According to the rules, the infantry can attempt to charge, but cavalry can react to a charge by countercharging. When they do, the infantry stop and become disordered putting them at a considerable disadvantage."
WHEN CAN INFANTRY CHARGE CAVALRY?As a followup, Alex clarrified how and when infantry can initiate charges against cavalry:
"Cavalry can only countercharge against a charge to its front as long as it is not in open order, disordered or locked in combat.
Infantry can charge cavalry, but it is not advisable to do it against the cavalry unit's front because the cavalry cavalry can countercharge. If they charge a flank or rear, then the cavalry can only turn to face. When cavalry countercharges infantry, the infantry stops and becomes disordered. See the section on countercharging on page 60. Actually the last paragraph of the first column on page 61. "