CH: A country that can do Sealion

If we're talking about an early 1940s timeframe :

Maybe the US, but they'd have to mobilize every single person and throw in every single resource into the build-up of their military infrastructure, particularly the navy and air force (and naval air wings too). Building up a submarine fleet would also be crucial to take out as much of the British fleet as possible, with little losses on their own side.

Generally, doing a Sealion of Britain would be easier up until the early 19th century. Britain creates a way too efficient coastal defence system after that era, heavily complicating any chances of success a Sealion-style operation might have.
 

CalBear

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The Soviets would have exactly the same problems the Nazis had with Sealion, so I don't think a Soviet Sealion by 1944 is any more likely than a Nazi one.

You do not NEED a navy, you need an amphibious force and a defensive force sufficient to get air supremacy. A fleet makes it easier to take the RN off the table, but it can be done from the air. It is insanely difficult to take a fleet out with air power, but it is doable (the USN destroyed the IJN with airpower).

What made Sealion impossible was that the Luftwaffe could not get even air parity let alone supremacy over the Channel. It is also extremely unlikely that the USSR could, but the Red Air Force was huge and quite capable and facing the RAF straight up it would have been interesting.
 
You do not NEED a navy (...) It is insanely difficult to take a fleet out with air power, but it is doable (the USN destroyed the IJN with airpower).

"You don't need a navy. The United States Navy destroyed the Imperial Japanese Navy with air power."

Um... that would indicate that you need a navy, by nature, surely? It wasn't the USAAF that destroyed the IJN. Air power is not, in itself, equivalent to either naval forces sufficient to close the channel and prevent invasion nor a decisive, crippling battle.
 

CalBear

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"You don't need a navy. The United States Navy destroyed the Imperial Japanese Navy with air power."

Um... that would indicate that you need a navy, by nature, surely? It wasn't the USAAF that destroyed the IJN. Air power is not, in itself, equivalent to either naval forces sufficient to close the channel and prevent invasion nor a decisive, crippling battle.

The USN was needed because Japan is 6,000 miles from the U.S. and the Pacific Ocean covers roughly a quarter of the Planet. That meant you had to do it with carrier aircraft.

The Channel is around 100 miles wide. Aircraft taking off from Normandy or beyond have about the same distance to travel as those launching from a carrier.

Air power could, very much, close the Channel. To take a rather extreme example 12,000 Yak-7 & 9, 5,000 La-5,2,000 La-7, 20,000 Il-2 &10, 2,000 Il-6 and 6,000 Pe-2 (this is about half of the Red Air Force, assuming a REich collapse in mid 1943) move them to France and no vessel bigger than an LST to move troops and try an invasion. The RN dies, the RAF dies, half of the Red Army force dies in the Channel and 300,000 troops make it to the beaches. (If you like, replace these aircraft with USN & USAAF models, really doesn't matter)


The Soviets did everything on a huge scale. They could afford to do it and had the resources. This is, of course, a thought exercise since the Red Army would never have been sent across the Channel, the prize isn't worth the cost, but could it be done without a fleet? Sure.
 
With a POD after 1900, there are only two countries that might do a Sea Lion, Germany and the Soviet Union / Russia. The US has obviously a much bigger potential, but a war between the US and the UK is much more unlikely, and the US would also need a base in France or the Low Countries from which to launch the invasion, which makes it a bit more unlikely still.

With Germany being much closer geographically to the UK, it is more likely to have the opportunity to manage a Sea Lion than the Soviet Union / Russia, but it is still rather unlikely. One basic problem is that in its war plans Germany is much more concerned with its continental neighbors than with Britain, and that the German leadership is not likely to predict that it will ever be in the posession of the Channel ports, with France completely defeated.

Another one is the fact that a German government that is intelligent enough to be able to mobilize Germany's resources to the extent of being able to invade Britain, is very likely also intelligent enough not to start a war against Britain in the first place.

But then again I feel tempted to show that, while unlikely, it is not altogether ASB.....
Germany's industrial potential is somewhat bigger than that of the United Kingdom.
Between the fall of France and Hitler's attack on the Soviet Union, the British Empire was facing a German-dominated Europe alone. For Britain, there were two potential Allies, the USA and the Soviet Union. I think a scenario is possible, where both are not potential allies. If Germany starts the war with a surprise attack on France and never attacks Poland, Poland is very unlikely to attack Germany. After all, France and Britain did very little in practice to relieve German pressure on Poland, and Poland, as the weakest country of the alliance Britain - France - Poland is likely to do still less for Britain and France. If the German attack on France and the Low Countries is a "bolt out of the blue", the Western campaign might be decided even before Poland has fully mobilized. Let's also say that in this timeline, there are no German demands on Poland. Poland would never allow Soviet troops on its territory and it cannot wage war against Germany on its own, so it is in effect a buffer state between Germany and the Soviet Union.

To eliminate the USA as a potential ally for Britain, we need an isolationist US president, and I think Robert Taft is the one who is most often mentioned in this context. In order to strengthen isolationism to make Taft president in the first place, I can think of three things that Britain can do: defaulting on its World War One loans, stronger and earlier protectionism, and a more repressive policy in India. I think all three of these mistakes could be made by a sufficiently right-wing, Mosley-like figure as prime minister. In order to bring someone like that into power, Britain must be in a much bigger crisis after WW I than it was historically. The most obvious reason for such a crisis can be a World War One outcome that is much less favorable to Britain and its allies. Two of the three mistakes that alienate the majority of the US population, namely more protectionism and repression in India, are also factors that weaken the UK by themselves.

So in order to get a situation that is favorable to a Sea Lion, we need a WW I with a result that is much more favorable to the Central Powers.

To be continued
 
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