One of the basic fundamentals of Napoleons success which was a unified command under one person and no pointless dispersal. As the years went on he seemed to forget those rules (I guess someone should have loaned him a copy of Sun Tzu)
You had as just one example Joseph and Jourdan who no one listned too who were both despised by Soult who was in turn loathed by Suchet. And thats not even counting the all the other pointless forces that marched hither and thither.
Even at the end when Wellington was invading France he did not unite Soult and Suchets forces under one commander.