To the best of ,my knowledge, the French marines are (naturally) from the French warships, formed into skirmisher companies for the attack on Savannah. It's very probable that many of the ship's complements of marines were under strength and numbers were made up using troops from the regular regiments. Coming from a variety of ships, it's also probable that their lack of common training, variable numbers and nature of their service aboard a ship would have caused difficulties if formed into regular line units. Thus, I think their use in the game as good missile troops (Light Infantry) with some bayonet drill seems OK to me.