There are many war games where the "health" of the unit will change for example the number of dices you roll. One game that does that is "wizard kings". The more health you lose, the weaker your attacks will be. The "Advance wars" video game or "Skirmish advance" board game implementation also does that.
Now I can see that it make sense thematically, but what are the impact on game play?
If wounded units have weaker offense, then they will not be used to attack. Therefore it should discourage the player to take the offensive.
If the game has many units, and unit stacking, it is not likely to have any impact.
But if the game has a low amount of units and no unit stacking, it could be more problematic and end up being hard to take offense. Or you will need to overrun your opponents with twice more units to secure a victory.
See any other pros and cons?