What if the British didn’t intervene and let the Germans defeat France.
In hindsight, I think there’s a very good case that the world would have been much better off as a result.
There has been lots of alternative history about that scenario. Tory historian Niall Ferguson has argued if the Brits stayed out the British would still be a world power comparable to the US. Quick history might of meant no Hitler or Russian Revolution.
Hussein wouldn't have had his blueprint for Fascism.
“The Guns of August” seems to suggest that even with the British intervention, if the Russians had not mobilized as fast as they did (causing the Germans to divert Western-front resources to the Eastern front) the Germans would still have taken Paris and ended the war before September.
Diary of Ann Frank, Schindlers List, etc., just in hindsight.