I've been researching flags used during the Napoleonic Wars and came across a description for the 1815 pattern French regimental flags. They are described as being 120cm square. This works out to 47-1/4" when converted. Given the other French and Napoleonic influence on Civil War culture, i.e. zouaves, kepis, chasseurs, battle tactics, etc., could it be possible that Beauregard used these flags as an inspiration for making the Confederate battleflag 48"x48"? Just a thought thrown out for discussion.