When I have looked into this a little before I noticed the following:

1. Before the 1.2 patch, units like hoplites took a lot of missile casualties marching. When they formed up in phalanx (at a much closer range) their casualty rate seemed to fall--despite that closer range. That seemed a bit odd and I thought it was some quirk of phalanx or a failure in the archery model. I didn't realize it applied to ALL units (that was a key bit I missed...)

2. After the 1.2 patch the animations look roughly the same to me on the march--with shields typically at their sides. However, the shield is being factored in to the calculation of whether or not they are killed. Casualty rates for shielded units on the march are way down.

3. When "individual" soldiers are "hit" but not killed while marching with their shields, the animation shows the shield swinging into position to deflect the shot. Quite a few men in a unit are now deflecting the shot.


That is my take on it. I have not yet tried to determine if the shield defense is in anyway "multiplied" now. I suspect it is just being added in while the unit is moving, whereas before it was not.