Да, есть такая цитата. Это не фейк.
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. In reaching a decision on that matter, we must first be clear about certain rules of war. Rule 1, on page I 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, and an army fighting there would be engulfed by what is known as the Ming Bing, the people's insurgents.
А вот источник: https://api.parliament.uk/historic-hansard/lords/1962/may/30/the-army-estimates#S5LV0241P0-00791