I think I read somewhere that the oak leaves were traditionally worn as an identifier on the battlefield pre Napoleonics. The multi-lingual nature of the Austrian Empire often brought regiments together who couldn't speak each others language and thus the oak leaves became an easy way to know right off who was friend or foe. I believe that during the Wars of the Three Kingdoms (ECW) it was not uncommon for troops to wear orange, yellow or red ribbons on their arms to identify them in the heat of battle. We are to used to the idea that all Royalists had twirled stashs and wore floppy hats whilst the vile parliement tratiors were clean shaven (everywhere) and wore round helmets whilst singing psalms in battle.
