Quote Originally Posted by Myrddraal
It doesn't. There is basic 2D collision to make sure soldiers don't overlap, but actual hits are not governed by 3d collision detection. Having collision detection on all those units would be a huge drain on the computer...
Seconded, i've definitely seen this stated explicity by CA (but cant find a link right now).

Note: The rate at which a soldier attacks (i.e. how many times per minute he attempts to hit an opponent) does seem to be determined by the animation system, but whether each attack is successful or not has nothing to do with the 3D animations. If anything it's the other way round - the game calculates whether the hit is successful via stats and random numbers etc, and then plays the correct animation based on the result.