Also, another way of looking at the line "Black and Blue/ and who knows which is which and who is who" is to remember that in many military conflicts up to the First World War, the chaos of battle was such that it became impossible to tell apart friend and enemy from a distance (as in some American Civil War battles, where the gray and blue uniforms were virtually indistingishable in the smoke).
Also, another way of looking at the line "Black and Blue/ and who knows which is which and who is who" is to remember that in many military conflicts up to the First World War, the chaos of battle was such that it became impossible to tell apart friend and enemy from a distance (as in some American Civil War battles, where the gray and blue uniforms were virtually indistingishable in the smoke).