That's pretty well known in the case of Napoleon and has a long history (see Caesar's "Gallic Wars"). But what was published in newspapers and elsewhere got back to the enemy, so why tell the truth? And why not put a positive spin on things for the general public (Wellington, after Albuera, saying of Beresford's report, "This won't do. It will drive the people in England mad. Write me down a victory.") Even today we have Pres. Bush and "Mission Accomplished."