In C&CN there are ni rules for reacting cavalry, that is to say cavalry reaction against an enemy cavalry charge happening in an adyacent hex. An example: a cav unit and an infantry unit are adyacent and an enemy cav charges moving into a hex adyacent to both, the cav and the infantry. In this case the attacking player may choose to charge any of them (the cav or the infantry). The rulebthat I suggest would command the attacker to charge on the cav instead of on the infantry if the deffending player wants. This rule (quite simple) is to reflect the protection that friendly adyacent cavalry gives to infantry, avoiding enemy cav from charging them as long as the charging hex is also adyacent to the deffending cav. Any comments would be appreciated!
I think this is an aspect of the turn rules, and it is incumbent on the defender to react it their turn to drive off the enemy cavalry attacking his infantry, perhaps from a source other than the adjacent cavalry.
Personally, if I was the original attacker, I would likely attack the defending cavalry first in an effort to write them down, rather than an infantry unit that could square up, and bounce my cavalry attack.
So in short, I don't really see the need here, and my reactive cavalry is often back further, ready to counter attack cavalry incursions.
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