So, you're Hitler and OKH and OKW. You are all warmed up to invade Yugoslavia within days and to settle the Greek question for good. And you're planning the year's main event, Barbarossa, for the end of May, when all the sudden......
....all contact with deployed forces in Scandinavia and occupied Western Europe is lost, border stations flying Danish, Dutch, Belgian and Luxemburger flags are operating with people in native uniform and no Germans in sight, and civilians undisturbed, and the German-French border is a swarm of French military activity and flags.
All these vanquished enemies are suddenly....unconquered. That's distracting!
So, you're Churchill and staff, you, strangely, start getting normal, unpanicked phone calls and telegraphs from Calais and Jersey and Guernsey, and oblivious civilian ferry boats approaching England, with skippers and passengers who are scared $hitless when ordered to heave to and boarded by heavily armed soldiers with deadly seriously expressions and hundreds of offboard guns and searchlights aimed at them.
Then there's newswire reports, in English and French, from Paris, with a date of 1940, giving no hint or acknowledgement of any German occupation.
It's miracle, France's defeat is undone, and France is psychologically and materially. in a state of being April 1940, one year prior to what Britain, Germany, and what the world outside of Western Europe, Denmark, and Norway are experiencing.
But it's somewhat of a cursed, or at least, a challenging miracle - The armies of the France, the Low Countries, Denmark and Norway may be back, but their weapons, training, and tactics are no better than they were last spring, the German forces, even absent the specific units that had been deployed in the Channel islands, France, Low Countries, Denmark, Norway, are institutionally *more* proficient than they were last summer, and there are plenty of them in Germany, Central and Southeast Europe. The British Army may be recovered from Dunkirk and the RAF recovered from the Blitz, but it hasn't established a track record of going toe-to-toe against the Germans....and winning. Combat again against the Wehrmacht and tactical Luftwaffe in Western Europe in the immediate future risks a new BEF getting thrown off the continent *again*.
Sure, the British can advise the French and other mainland countries to not make the errors that played into the hands of the *old* 1940 German plan. But all radio and signals intel indicate to Hitler and everyone in Berlin and Germany it is 1941. When they come west, it will be with a new plan, with unpredictable details.
Meanwhile, what is Stalin making of this science fictional event? Certainly, disbelief at first. But when the irrefutable physical evidence comes in, a sense of relief that the European situation is not so lopsidedly in Germany's favor, as risky as it had started appearing for the USSR to Hitlerite blackmail, and now more balanced between the west and Germany as Stalin expected a war would be when it started in September 1939. But does this sense of relief or opportunity translate in Stalin's mind into a call for any new action on his part, in either the military/defense sphere, or the trade sphere?
Getting back to Hitler, after X number of hours getting over the disbelief, what next? Cancel the Balkan invasion plans, transfer all but minimal defensive forces west (and possibly north), and strike the west ASAP? Does Germany any longer have the naval combat ships and naval lift capability to make the long lift to Norway, especially its central and northern parts?
Or, with the current concentration of forces and logistics right there in the Balkans to crush Yugoslavia, is it best to quickly proceed and crush that enemy and Greece to rescue Italy and close that front (whether Crete will be included, or more likely, not), and thence pivot forces for an all-out offensive to the west, dragooning Italy and minor Balkan allies in to provide some additional mass in case of any improved French & Low Countries alertness or uptime British interference?
