See Macdonald's after-battle report to Eugene:

'While all was in motion to put this operation into execution Your Highness saw that the enemy had anticipated the prince de Ponte-Corvo in his attack and was sending numerous corps against our left. This prince, apparently unable to fight against forces which appeared superior to his, began to retire'...........[Napoleon orders Macdonald's troops forward] ... 'It was then that I met the prince de Ponte-Corvo, ”I am going to debouch on your left” I said to him, “My Saxons will support you” he answered. But hardly had several of my battalions arrived beyond the hillock when the Saxons precipitately retired to the rear, in spite of the efforts of the Prince de Ponte-Corvo to hold them, and held up (but only briefly) the march of my troops.'

I do agree that Napoleon's letter is a trifle petulant - one can only speculate on his motive for writing it since very few of the recipients would have read Bernadotte's original order.

Susan