You know, I've read a great deal of debate on whether that photo is staged or not. On the one hand it does look staged, but the question is when was there a chance to stage it? it's a French photograph, and as the entire French army was captured at the Battle of Sedan, there was no chance for the French to stage it (one can tell it was after or during the battle by the destruction). The Germans faking a battle for a French photographer seems a rather unlikely situation.
Another thing in its favour is the existence of another photograph from the same location.
This second photo looks much more realistic. You can see heavy gunfire in the direction of actual people (and I doubt they carried blanks around), lots of smoke all around and what appears to be a large explosion in the upper right corner.
Even if they are staged, they're still are useful images of the battlefield taken shortly after the battle. If they are real, they are some of the earliest photographs of combat ever taken, though I have seen one from the US Civil War that looks very much to be of a battle.
