In Napoleonic wars era, a line contains mostly regular troops except for two kind of elite units, the heavy one, e.g. grenadiers, they normally are the bravest, strongest troops with the best stamina, suitable for shock troops which is posted to the right, and the light one who are normally the best shooters/skirmishers, normally posted in the left flank.
What is the advantage or the motivation of this particular arrangement? I could somehow understand why the best units are posted at flanks , possibly to allow or guard against flanking attacks, but why is there preference to post best storm troops to the right and best shooters to the left (as opposed to the other way around, or have it symmetrical)?
