This book offers a new perspective on an old subject. That is why did Napoleon's marshals, so successful in corps command, fail when given an independent army command? It examines in detail the defeats of Marshal Nicolas-Charles Oudinot at Gross Beeren, Marshal Etienne Macdonald at Katzbach, and Marshal Michel Ney at Dennewitz. Many authors have speculated why these marshals failed in independent tactical command. They have offered such reasons as lack of talent, lack of guidance from Napoleon or the failure to understand the nature of Napoleonic warfare. While these reasons are valid, they are contributing factors rather than the primary reason for the failure of Napoleon's marshals.