[Companion]

A supplement to Tim's comments:

Well, if your PCs are executing cavalry charges and unloading troops in the SAME TURN all the while enemy is WATCHING, your dismounted Infs are bound to suffer more casualties and suppression than when advancing slowly by foot.

After all, mechanized infantries are still infantries who happen to ride around battlefield protected in steel (aluminium?) taxis.

And... yes, artilleries of every caliber just love infantry.
They love to chew up enemy infantry (AAA class tender meat compared to armors)
and love to support friendly infantry.... (in every army, every terrain, every situation, artillery remains as the truthful companion of infantry)

Good luck

- Comp