A unit removed for too many "casualties" is not "wiped out", it is merely no longer an effective force on that given day. What would happen after the battle is that many soldiers would return to their camp and the unit would be built back up from that cadre.
For an on-going campaign such as "The Alpian Wars" I am using the following simple formula for determining how many men return to their unit:
- 1st casualty -- returns on a d6 roll of 2 or better
- 2nd casualty -- returns on a d6 roll of 4 or better
- 3rd casualty -- returns on a d6 roll of 5 or better
Some three weeks after the Battle of the Crossroads (and a certain amount of command changes and reinforcements) word has reached Stagonia that a large Alpian force under General Rossi will attempt to force its way through the passes of the Bellevue Hills into the rich wine valleys of Stagonia . . . and General Murdeau has been given a force to try to slow Rossi down, beat him to the Bellevue Hills and prevent the Alpians from breaking through.
Soon we will find out what will happen.