Russians and German
By Yep; we do tend to forget that by the time Tom Hanks saved Matt Damon in Normandy, the Red Army was regularly crushing the Wehrmacht (which, when it could fight on even terms, regularly crushed the British and US armies) on the Eastern Front. The democracies ended up on the right side in World War II, but it’s more likely because they had sensible leadership than because of their ability to field powerful armies.
Greg Easterbrook is an idiot. For a good history of the real World War II, see When Titans Clashed by David Glantz and John House.