I wrote a book not long ago (in French) in which I studied in great details the campaign of 1812 in Russia with the advance to Moscow and the long painful retreat back to France. By the time the Grande Armee recrossed the border of Russia in jan 1813, there was less than 5% of the men still alive and those were more ghosts than men.
So, in essence, Napoleon lost everything there, his horses, his army, his invincibility and finally his throne.
Yet, it is interesting to notice that unlike the Germans in 1941-45, Napoleon did not lose a single battle against Russians. In fact he won them all, even at the end when all his men were in rags. The winter of course and the lack of supplies slowly got the better of him.
So my question is this. Was it possible for him to conquer Moscow and get the huge propaganda benefit from this and at the same time save his army and win the war?
The Germans failed but the mongols in the 13th century and the Polish in the 17th century faired better... What do you think?