According to Captn. Fishpants (MikeB at the .COM);

We're ahead of you, and this is already done.

This is why some Generals can get Physicians and Doctors as members of their retinues. They'll aid recovery of 'dead' soldiers after a battle, so not all casualties are necessarily dead. During the battle they'll be combat ineffective and show up as 'dead', and then afterwards there's a chance that they'll be recovered and added back onto a unit's roster of men.
Now, this is a VERY welcom feature.

Barkhorn.