] He is one of those who argue that Napoleon lost Waterloo, not that Wellington won it(?).

I could agree that Napoleon with a much greater force than Wellington must be expected to win the battle. The question is is one of battle tactics. Who was the better general.

The Prussian army marched away from the battle area. Napoleon sent off a much larger portion of his army than Blucher had with the intent of revenging himself on the Prussian. The Prussians were to be destroyed as they escaped for Germany. Napoleon kept most of his army at the battlefield to finish off Wellington.

But Blucher was not going to Germany. He was going for a stroll in the woods, and when he had got more or less between the French army following him and the Napoleon/Wellington forces he turned straight back to the battlefield. His arrival told both sides that Wellington had won a great battle that the military text books going back to Thermopylae said had to Napoleon.

Napoleon could easily have defeated Wellington, but Blucher's return, leaving the French punishment army behind him, gave Wellington superiority in numbers on the battlefield. Wellington said that it was a near-run thing. Napoleon ought to have expected that Wellington would not simply let his British and German (other nationalities, too) be destroyed by a straight slugging match. What makes a great general is finding something unexpected to do, as Lord Louis Mountbatten did in planning the invasion of France to happen in bad weather and in Normandy. Mountbatten also used bad weather in the Burma campaign. He attacked in the monsoon season, completely unexpected, with an enemy not prepared to defend itself in floodwater conditions.
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