What tactic did Daniel Morgan's riflemen use that was not the old
European way of fighting?

Morgan's Riflemen or Morgan's Rifles, previously Morgan's Sharpshooters, and the one named Provisional Rifle Corps, were an elite light infantry unit commanded by General Daniel Morgan in the American Revolutionary War, which served a vital role executing his tasks because it was equipped with what was then the cutting-edge rifle instead of muskets, allowing for a Rifleman to have an effective range of double that of the average Infantryman

these acts divided the south into five military districts.