One of post-1900 AH scenarios that I found quite interesting is the one where the Nazis were nipped in the bud. My preferred choice is in September 1939, when the majority of Wehrmacht was busy in Poland.
So, assuming that Great Britain and France immediately throwing the bulk of their armed forces into the relatively undefended Germany:
- How long would it take for the British, French, and Soviets to occupy the whole Germany? Before or after the end of 1939? (here I guess Stalin will eagerly join the party and declare outright war on Germany)
- What would the Allies (minus Americans) do to Germany in the aftermath? Depose the Nazi government? Dissolve Germany for good and balkanize it?
- How would Fascist Italy react? What would Benny do?
- How would this affect the Second Sino-Japanese War and the incoming Pacific War?
- How would the ATL WWII be played out? My bet is Great Britain, France, United States, Nationalist China vs. Soviet Union, Communist China, Imperial Japan. Dunno about Italy, Spain, Hungary, and other Fascist European states...