Couldn't find anything in the rules to prevent the cavalry fighting back, unless somebody can tell me different.
A cavalry unit wishes to attack a square. The cavalry unit has no retreat or 'bounce' path behind him due to other units occupying those hexes, one of which is an enemy unit.
The square rolls first and rolls a flag. The Bounce Flag rule on page 20 state - para.1 - "If the cavalry unit can not retreat, it loses a block for each retreat hex the cavalry unit can not fulfill." That's easy enough so the cavalry lose one block but stay in the same hex. Now to the cavalry. It seems they are still allowed to attack the infantry because the rule goes on to state - para 3 - "If the cavalry unit is not eliminated or forced to retreat from its hex when being attacked by infantry in square, the cavalry may melee against the infantry square". The words sticking out there for us was "FORCED TO RETREAT FROM ITS HEX" which in this example it was unable to do.
So the simple question is 'Despite getting a bounce flag against them, is this cavalry unit is still allowed to melee' ?
"Forced to retreat" includes leaving the initial hex.
1. If the Cavalry is still adjacend in the inital hex = it may attack the square
2. If the Cavalry leave the initial hex, it can´t attack the square, also if it would be again adjacent to the square (in another/new hex).
I used to assume the Bounce Flag meant that the cavalry ALWAYS would not get a return dice roll to attack. But no, yesterday's example showed that they can (and they eliminated a single block square by being allowed to roll).