Andrew Roberts cites an extract from a letter by Napoleon about his generals’ way of fighting the British in Spain:

‘As long as they will attack good troops like the English, in good positions without making sure they can be carried,’ he continued, ‘my men will be led to death to no purpose.’

CG9 no. 21865 p. 1052, August 21, 1809

Roberts, Andrew (2014-10-02). Napoleon the Great (p. 850). Penguin Books Ltd. Kindle Edition.

I find it an interesting observation by the Emperor knowing that it is exactly what he will do 6 years later at Waterloo. And I don’t think it’s the only instance where Napoleon violated his own rules of warfare. Fighting with his back to a river at Wagram comes to mind.