Successful Sealion

I am going to write TL about World War II in which Nazis invaded Great Britain before Operation Barbarossa (which I will move to the 1942 or 1943) and was able to hold southern England cities.

My plans would be:

1. Stronger fascist and pro-German movements which will advocate fight against communism with Germany as ally. I think that many British soldiers will see Germans as ally instead of foe.

2. Slower British advances during early days of war - due to danger from fascists and certitude that they will begin uprising - most of the forces will remain on home island.

3. Destruction of the demoralized BEF (by fascist propaganda) in France and rise dissent in Great Britain ("they sent our boys to senseless die"). Due to demoralization of BEF Fall of France will be quicker and less bloody for Germans.

4. Luftwaffe defeats Royal Air Force above Britain (no foreign volunteers, desertion and low morale).

5. Extended Uboat campaign from 1939 to 1941, use of auxilliary cruisers.

6. Seizure of Egypt by Italians.

7. Uprising performed by fascist movement captures some of southern cities in England which enable Kriegsmarine to transport some troops there (after engaging Royal Navy by Unterseebootsflotille) and hold these ports.

8. Cooperation between Stalin and Hitler (after Uboat campaign and defeat of RAF they would be more conviced to cooperate). Raw materials, maybe event KV-1 tank's plans for Germans. Seizure of Finland by Soviets in colaboration with German military advisors.

9. Stalemate on British front, sinking of American ship carrying supplies by Uboat for Britain and declaration of war by USA against Germany.

Is this possible?
 
This will be fun.

Im amused how 1 and 8 cancel each other out, and how 2 and 7 present ... difficulties. 5 could also be expected to provide the RN with more practice against submarines. 6 is interesting, given what we know about logistics and the desert (and the Italian army). 7 shows a lack of knowledge of the difficulties of the English Channel for submarines.

4 is more complicated - even if the RAF is 'defeated', it can still pull back North, and await Cromwell to throw everything left at a too-busy Luftwaffe.

9. implies Sealion has not, in fact, succeeded. Some review of port capacity along the south coast of England could be in order as well.

To answer the OP's question 'No. Not without making the RN magically disappear'.

PS 'With his alliance with Stalin, Herr Hitler has betrayed fascism. Indeed, we of the B.U.F. must continue our efforts to save England and the Empire as part of the National government'.
 
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No. Just no. I highly suspect that a realistic Sealion couldn't be done without German victory in the Great War and then a German government singlemindedly focused on the British Empire's destruction "Albion delenda est" style. With 20-plus years of preparation and build up, Operation Sealion might be possible, probably with about a million German (plus any German ally) casualties unless Britain surrenders early enough in the invasion.

But that's not realistic. Why not just trade with Britain instead and reap the benefits that way instead of all that pointless military buildup followed by massive pointless destruction? That's what the majority of German politicians and citizens will be thinking come the end of the Great War. And the vast majority of their British counterparts will come along to that very soon.
 
1. Who said that Hitler will honour alliance with Soviet Union forever?

2. So Germans would be forced to improve their tactics.

3. I thought that in case of uprising on home islands many soldiers from Egypt would be transported to Britain. Or would be still on transport ships when uprising started.

4. Submarines should engage Royal Navy anywhere in order to pull away them from English Channel.

5. Yep, my argument is invalid.

6. When saying successful Sealion I meant landing on British isles and holding line until Panzers and other stuff arrives.

I wonder if fascist uprising in southern cities and mutinies in navy could make invasion successful? Germans would have friendly forces in British southern ports and only task for them would be avoiding Royal Navy. But RN could be engaged by submarines and be late when enemy troops landed in England.
 
6. When saying successful Sealion I meant landing on British isles and holding line until Panzers and other stuff arrives.

I wonder if fascist uprising in southern cities and mutinies in navy could make invasion successful? Germans would have friendly forces in British southern ports and only task for them would be avoiding Royal Navy. But RN could be engaged by submarines and be late when enemy troops landed in England.
No. It cant.

The English Channel is hell on earth for submarines - it is shallow, and it has odd tides and so on.

Ignoring the lethal effects of this for any invasion launched with other than the sort of purpose-built landing ships that sends the UK into a frenzy of shipbuilding, it means the English Channel is very very unhealthy for submarines trying to hunt ~25 knot warships.

In any case, you just summed up the major problem.

For the RN to "be late when enemy troops landed in England" is absolutely credible. But this doesnt mean they are sufficiently delayed until "Panzers and other stuff arrives".

Im assuming you can read a map ? Tell me which ports in Southern England you are thinking of, and then tell me which of them can support, say, the level of cargo the Germans got into Stalingrad by air, which is the absolute minimum of "other stuff" a German campaign in England can support.

Then, tell me how the RN cannot interdict these ports.
 
What is your understanding of Fascist sympathy in UK during this period?

Close to nil after Poland and France I would suggest. It's one thing to admire a strong man leader in peacetime. It's a completely different thing to turn traitor to your own country in wartime. There just wasn't the anti-government movement even within the Blackshirts. Most of them just wanted a different PM.
 
So, you are right. It is impossible to happen.

But, what about German Naval Bombers based on land or on Carriers? I think that they could cripple some British ships (especially ship with obsolete Anti aircraft guns). Is this more possible than using submarines?

What about even earlier PoD when Entente removes or reduce ships/aircrafts limit for Germany?
 
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So, you are right. It is impossible to happen.

But, what about German Naval Bombers based on land or on Carriers? I think that they could cripple some British ships (especially ship with obsolete Anti aircraft guns). Is this more possible than using submarines?

What about even earlier PoD when Entente removes or reduce ships/aircrafts for Germany?
The RN had about a 10:1 advantage against the Kreigsmarine in the historical 1940, and for Sealion to happen, the Germans have to keep the Channel open for shipping for at least two weeks.

Additionally, the German naval bombing was very bad in 1939-1940 - its something that is hard and needs a lot of practice.

That means "Some" isnt enough. You need to increase that to 'most' - and crippling isnt neccessarily enough, either - Michelet's 'A Better Show' had a very crippled Revenge drifting along an English coastline during a Sealion, firing it's sole remaining secondary turret at the German beachhead before being finally sunk.

In fact, go read A Better Show :) It's well worth it.

https://www.alternatehistory.com/forum/threads/a-better-show-in-1940.103866/
 
So, you are right. It is impossible to happen.

But, what about German Naval Bombers based on land or on Carriers? I think that they could cripple some British ships (especially ship with obsolete Anti aircraft guns). Is this more possible than using submarines?
...what carriers?

What about even earlier PoD when Entente removes or reduce ships/aircrafts for Germany?
Why would making it WORSE for Germany help?
 
Sorry, I meant limits in aircrafts and ships.

If Entente allowed Germans to have small airforce, Germans could improve naval bombing and invent better naval bombers than OTL (they would have 20 years). Maybe some of them would be based on carriers in order to quicker strike on enemy port/flotille. After rearmamanet began by Hitler many "more modern than OTL" naval bombers could be produced and used to defeat Royal Navy.
 
Sorry, I meant limits in aircrafts and ships.

If Entente allowed Germans to have small airforce, Germans could improve naval bombing and invent better naval bombers than OTL (they would have 20 years). Maybe some of them would be based on carriers in order to quicker strike on enemy port/flotille. After rearmamanet began by Hitler many "more modern than OTL" naval bombers could be produced and used to defeat Royal Navy.
The problem you have there is that Germany does not have any experience with carriers and the two they built were never completed. Hell, the second way never got much beyond I believe the keel being laid down. If you have Germany build more carriers then you end with the problem of where you build them. After WWI Germany was left with just a handful of slipways capable of being used for the construction of major naval vessels and the ones they did have were soon filled with the Twins (G&S), Bismark & Tirpitz and then the carriers, only one of which was even launched. Carriers are not defensive weapons, they are offensive, so if you have Germany construct more slips and then build yet more carriers then you have a problem in the shape of the RN suddenly getting its greedy mitts on a lot more funding for yet more battleships and carriers of their own. If you want to see some of the pitfalls, read Gudestein's effort. He had to bend the rules so many times that the Mods gave up and stuck it in the Writer's Forum.
 
Is this possible to make artillery cannon that would be able to fire Dover from Le Gris Nez in 1940/1941? It's 34,8 kilometers. I know that this cannon would be target for Allied bombers so are should be protected by many modern (1940) anti-aircrafts guns and interceptors but it could make defence of Dover weaker (cannon would be inaccurate but British morale would be shattered when artillery shells are pounding at city and neighbourhood).
 
Is this possible to make artillery cannon that would be able to fire Dover from Le Gris Nez in 1940/1941? It's 34,8 kilometers. I know that this cannon would be target for Allied bombers so are should be protected by many modern (1940) anti-aircrafts guns and interceptors but it could make defence of Dover weaker (cannon would be inaccurate but British morale would be shattered when artillery shells are pounding at city and neighbourhood).
Dover is one of the two ports that might conceivably maybe make a difference for the German resupply effort that Sealion depends on.

Trashing it with long range artillery will, therefore, immeasurably help the British defence.
 
Towards the end of 1940 the German Army started installing their huge guns on the French coast that could fire shells across the channel, the first was the 38cm gun at Siegfried battery just south of Cape-Gris-Nez, followed by Three 30.5 cm guns at FRIED AUGUST BATTERY north of Boulogne, Four 28 cm guns at GROSSER KURFURST at Cape-Gris-Nez, Two 21 cm guns at PRINZ HEINRICH BATTERY just outside Calais, Two 21 cm guns at OLDENBURG BATTERY in Calais, Three 40.6 cm guns at LINDEMANN BATTERY between Calais and Cap-Blanc-Nez, Four 38 cm guns at TODT BATTERY outside Cap-Gris-Nez. These guns were later backed up by three K5 railway mounted guns which were also capable of firing shells not only across the channel but also at allied shipping in the channel.

However, I doubt the usefulness of these guns. Guns did not score a lot of hits on the Allied Navy and the British responded with accurate bombardment heavy guns at Dover (nicknamed "Winnie" and "Pooh") was effective and disabled the Batterie Grosser Kurfurst at Floringzell.

For instance, On the 22nd August when the East-bound Channel convoy was approaching the Dover Strait it came under long-range fire from heavy guns situated near Gris Nez. The bombardment continued for nearly 3 hours without success, 108 rounds being fired apparently in four gun salvoes. An enemy battery of four guns and another of three guns were located. Two shells landed in Dover harbour, one narrowly missing a minesweeping trawler. Of the 108 shells, only three shells hit or came close to their targets. If you wish to weaken the defenses around Dover, a LOT of shells will be needed. Dover and its harbor is going to be leveled.The Germans have just effectively destroyed the port they need to sustain their army (if they can even land one) and must now rebuild it. Not exactly the best use of German resources.
 
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The problem with heavy guns is that they are all but worthless against ships in the Channel, especially destroyers. So using them to protect the invasion fleet isn't going to work.

And I don't see any way the German's are going to get a port, they were just too well defended and would be demolished if seriously threatened. Couple that with the lack of true amphibious craft and that the hodge-podge collection is going to have serious problems with the weather in the Channel and the German's have a disaster on their hands, not to mention the RAF and RN...
 
Heavy gun would be not used against ships but against cities in southern England in order to destroy them (buildings, people, power plants, factories, airbases etc.).
 
The problem with all successful Sealion Timelines are that if enough factors are altered to make the invasion at all feasible the the British would have taken Hitler up on his offer and negotiated a peace as resistance would have been pointless. An example being the BEF being lost in France.
 
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