The quote, usually known from the Princess Bride, is actually from Field Marshall Montgomery addressing the House of Lords:
The next war on land will be very different from the last one, in that we shall have to fight it in a different way. Rule 1, on page 1 of the book of war, is: "Do not march on Moscow". Various people have tried it, Napoleon and Hitler, and it is no good. That is the first rule. I do not know whether your Lordships will know Rule 2 of war. It is: "Do not go fighting with your land armies in China". It is a vast country, with no clearly defined objectives.
Montgomery didn't say except in Winter. He said don't do it all.
The next war on land will be very different from the last one, in that we shall have to fight it in a different way. Rule 1, on page 1 of the book of war, is: "Do not march on Moscow". Various people have tried it, Napoleon and Hitler, and it is no good. That is the first rule. I do not know whether your Lordships will know Rule 2 of war. It is: "Do not go fighting with your land armies in China". It is a vast country, with no clearly defined objectives.
Montgomery didn't say except in Winter. He said don't do it all.