Operation Sea Lion (1974 Sandhurst Wargame)

Oh, Stenz, no doubt that 4,000 defenders of mixed quality strung out all over a 150 square mile island can defeat 20,000 attackers landed in the first 24 hours, with 10,000 more per day coming in after that. How could they not possibly win against that tempo?



The advantage of numbers, elite troops, and masses of Luftwaffe close air support, obviously.

20,000 Attackers paratrooping in the first 24 hours? Sure, maybe. And 18,000 of them will have broken arms or legs, thrown backs, snapped necks, or twisted ankles. We call these "Walking Wounded" at the best and "Dead" at the worst. You CANNOT throw a man out of an airplane with no training and expect him to survive unharmed.
 
Oh, Stenz, no doubt that 4,000 defenders of mixed quality strung out all over a 150 square mile island can defeat 20,000 attackers landed in the first 24 hours, with 10,000 more per day coming in after that. How could they not possibly win against that tempo?



The advantage of numbers, elite troops, and masses of Luftwaffe close air support, obviously.
explain how you get 20000 landed in first day
 
explain how you get 20000 landed in first day
Given that they landed 3,000 in The Hague in a few days, and at Crete 22,000 were involved and the battle took 2 weeks, I think they need to be teleported.

At Crete they used (per Wiki):
New airfields were built, and 280 long-range bombers, 150 dive-bombers, 90 Bf 109s, 90 Bf 110s and 40 reconnaissance aircraft of Fliegerkorps VIII were assembled, along with 530 Ju 52 transport aircraft and 100 gliders.
 
Ten sorties a day with "paratroopers" taken straight from line regiments, and with JU-52's that don't actually exist, supplemented by medium bombers that are supposed to be performing four other jobs as well.
might as well draft them from the kreigsmarine.....cause most of them will end up in the sea.
 

Deleted member 94680

Oh, Stenz, no doubt that 4,000 defenders of mixed quality strung out all over a 150 square mile island can defeat 20,000 attackers landed in the first 24 hours, with 10,000 more per day coming in after that. How could they not possibly win against that tempo?



The advantage of numbers, elite troops, and masses of Luftwaffe close air support, obviously.

Those statements are mutually exclusive.
 
OK, guys, I'm back. I was contacted by PM as to why Knickebein would be such a failure, and I was reminded there is a solution to 98% of the silliness in this thread: to ignore its source. So I'm willing to give it another go, because:...

Still, while there is no saving Glenn, because as numerous psychological studies have shown mere facts cannot shift a person's views once they have reached a certain point we can prevent others becoming so divorced from the evidence. For every Glenn there are a hundred, maybe even a thousand casual readers whom he hopes to influence by getting a post through unrebutted. Demonstrating the evidence points to certain facts and those facts preclude the viability of Sealion is thus worth doing in an age where misinformation is spawning like a toxic malady.

...because you make it look like a dereliction of civic duty not to inform the uninformed here. Damn.

The same argument about the Royal Navy could have been made at Crete; is the Luftwaffe not as good at bombing ships in 1940 compared to 1941, and why?

No, and here is why. 1. is Crete 1941 and 2. is Isle of Wight July 1940.

A. The effectiveness of all bombers, and in particular of the Stukas (the only meaningful bomber when it came to hitting a non-moored warship), depends on not encountering enemy fighters.
A1. The Germans started with air superiority and ended with air supremacy.
A2. Control of the air is contested between 644 British single-engine fighters operating pon their own turf, with the support of the best air defense system in the world, and with AA help, and 760 German single-engine fighters (figures July 6, all serviceable aircraft in Europe). Guess who establishes air superiority and starts bringing down enemy bombers. As a guideline, think OTL Battle of Britain, only the Germans are converging on one spot.

B. The Stuka, as mentioned above, is the main ship killer, and the only effective one if the ship isn't moored.
B1. The Ju 87D had a maximum weight at take-off of 6,600 kg. Top speed 410 km/h. Range 1535 km. Payload 1,800 kg, which could include as a single maximum-weight bomb a 1,000-kg bomb. The latter was available in numbers in an AP version - the only thing that would have good chances of piercing a battleship's top deck. The Stuka pilots deployed to the Med had received additional training and experience as to navigating over open sea and hunting and hitting maneuvering targets, and they were select crews.
B2. The Ju 87B had a maximum weight at take-off of 4,300 kg. Top speed 382 km/h. Range 595 km. Payload 700 kg, which could include as the biggest bomb a 250-kg bomb. The latter, in July 1940, was not available in great numbers in the AP version. Thus, even a hit on a cruiser top deck would probably only cause superficial damage, and even a destroyer might survive a hit with that. Some of the Stuka pilots had received some direct experience in targeting moving targets over Dunkirk, but most of them had no such experience and no training.

C. The Royal Navy operates at night and in bad weather.
C1. The naval part of the German landing on Crete was pushed back by the Royal Navy, with heavy German casualties, in a night-long engagement.
C2. The same but worse. A sudden worsening of the weather makes the day the same as the night for the Luftwaffe.

D. Warships carry their own AA, but that is only good for as long as the ammo lasts.
D1. Several British warships withdrew from Crete only after having survived repeated air attacks - but they had used up all of their AA ammo. ISTR a cruiser that repelled the last German air attack by firing its training rounds. Then it had to fall back towards its distant base.
D2. The nearest British base is half an hour away. If for some incredible luck the Germans manage to make it temporarily insecure, there are others within a couple of hours.

E. The number of targets is important.
E1. Do some homework and look up how many warships were around for Crete.
E2. Do some homework and look up how many warships would be available just in the Channel, let alone the whole Home Fleet, in July 1941.
 
[snip]ISTR a cruiser that repelled the last German air attack by firing its training rounds. Then it had to fall back towards its distant base.

It was actually one of Mountbatten's destroyers, Kelly IIRC. I believe it was sunk and in its last moments was down to firing training rounds as that's all it had left.

RN ships off the IOW will not have such resupply problems...
 
What 20,000 attackers? All elite troops? 1st Fallschirmjager had 15-20% losses in May, not including wounded - say a very conservative 10% in addition. Leaves a fighting strength of maybe 8-9,000, before injuries due to night drops in unfamiliar terrain.

They also lost 140 or so JU52's, which gives an idea of the attrition rate landing in the "improvised airfields".

Where do another 10,000 a day land? Not on the north coast - they'll be chewed to pieces by the RAF bombs, RN shells and torpedoes and Army artillery. So by boat from ships anchored off Sandown and Shanklin? Getting chewed up by MTB's, ML's HDML's and anything that can float and mount a couple of machineguns.

:)
 
Oh, Stenz, no doubt that 4,000 defenders of mixed quality strung out all over a 150 square mile island can defeat 20,000 attackers landed in the first 24 hours, with 10,000 more per day coming in after that. How could they not possibly win against that tempo?
You mean "8-9,000, before injuries" and drowning in channel, attacking 4,000 defenders that are mostly guarding semi or fully fortified positions (even old castles are hard to take with only rifles/MGs) with phone lines to heavy artillery support?

That the defenders are also sitting overlooking the main port to the north that will allow easy resupply if they don't get take immediately only makes it worse....
 
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It's not that easy to do a surprise-attack at Cowes. You're gonna get in the range of several coastal artillery batteries.

The way airborne troops take Cowes is they land in the center of the island then move north into the city. Those coastal batteries they would try to capture intact from behind.

You do realise that the IOW had a radar station which was part of Chaine Home Defence? Even if they wouldn't expect an airborne attack on the Island, the airdefence batteries would be alerted, simply because shooting at planes flying over, is kinda what they are for. It would soon become obvious what was happening.

Wow, AA batteries would be alerted? Better stop the war before someone gets hurt!! :^)

Yes, the first hint that I realised that Chain Home was on Isle of Wight was the times when I said that capturing the radar station intact for examination was an objective. Hey, think the jamming of Chain Home that the Luftwaffe is able to do come August gets better after capturing this station intact? My guess would be that an intact functioning station in German hands is....bad...for the RAF? What's yours?

As for seaborne surprise: the RN didn't just sit back and relax, but was actively patrolling the channel, so they would be on alert, and not just sleeping at their watches. To attack Cowes harbour with surprise: you need to get through a narrow seaway. The chances of getting there unseen are slim.

Any seaborne landing is in the south, and any attack on Cowes comes overland by road from the south.

The RAF and LW have parity. The LW couldn't win the BoB, what makes you think it can win the battle of IOW. Also remember that in the BoB the LW could always choose when to attack, and the RAF had to react, while on the IOW the RAF can choose the moent of attack, and the LW has to react. And they won't have early warning, and their fighters will be mostly stationed in France, so with that reaction time, the RAF-bombers are already back on their base by the time the fighters arrive. To do a constant CAP they don't have the fighters.

No, the RAF is on the defensive, the Luftwaffe is on the attack. The RAF sucks at ground support and ship attack. The Luftwaffe is good at both. RAF 11 Group can attrite the LW in this battle, but it cannot stop the attack. British troops on and around IOW are going to be pounded by the Luftwaffe in heavy air attacks. You understand? It's the entire bloody Luftwaffe concentrated into one battle the size of Crete. The RAF doesn't "do" effective close air support at this time, and won't until it learns how in Africa later.

Nah, they don't need a large chunk of their reserves. It was already pointed out to you that at the hight of the invasion scare, the British army send an armoured division to Egypt. They can send that instead to IOW.

I think you might be underestimating the problem a bit.

After the meatgrinder around Wight, what escorts do the germans have left? They started the operation with less than 10 destroyers.

A Channel convoy might be composed of three or four 200 to 1,500 ton scow transports, escorted by a scratch force of maybe a half dozen converted trawlers and such with heavy AA or light cannons up to 4", plus dozens of small MB's and such for picking up men in the water. Overhead, hundreds or thousands of LW anti-ship sorties going after anything RN that is attempting to intercept. Same thing. Every day. Can you see how after a few days the RN might conclude that losing 4 destroyers a day can't be sustained, just to sink 3 or 4 scows that can be replaced by hundreds of others? That's the power of coastal shipping tactics.

But I guess you think that the barges will self-protect them. I'm afraid you're ridden with the victory disease.

No, you don't understand the SLOC problem for the RN. "Barges" refers to massed shipping movement related to the transfer of entire armies at sea in one lift. A supply convoy is two or four small expendable ships, easily replaced, escorted by a half dozen small ships, also easily replaced, repeated one, two, three times per day, every day, under skies with the Luftwaffe overhead.

The LW will be quite busy with supplying the IOW, protecting the shipping and planes doing that. Probably also needing to suppress coastal and regular artillery opposite of the IOW, and to make sure the RN doesn't interfere.

How did you arrive at the conclusion that the entire Luftwaffe committed to one small battle could not attack warships and provide close air support at the same time?

BTW. Earlier you said that step 1 was to get the RN to abandon Portsmouth. You seem to have left that out now. Don't you think that a month of bombarding Portsmouth would be some kind of signal that something is about to happen there? Unless of course if they bomb al the ports, but with what planes?

So answering 25 posts a day, now I have to relist all the stuff that's already discussed too? Pass. Bombing would have to be all the RN ports on the south coast, but heavier with Portsmouth. Primarily with twin engine types, primarily at night is the sketch.
 
Glenn so again you are stating that the Germans can make large logistical and doctrinal changes as needed but the British are stuck with their historical abilities?
That seems questionable.
 
The way airborne troops take Cowes is they land in the center of the island then move north into the city. Those coastal batteries they would try to capture intact from behind.

The Coastal Batteries are on the mainland and cover nearly all of the Isle of Wight coastline

So....they would have to be captured by invading the mainland now?

I am reminded of that song "There's a hole in my bucket"
 

nbcman

Donor
The way airborne troops take Cowes is they land in the center of the island then move north into the city. Those coastal batteries they would try to capture intact from behind.



Wow, AA batteries would be alerted? Better stop the war before someone gets hurt!! :^)

Yes, the first hint that I realised that Chain Home was on Isle of Wight was the times when I said that capturing the radar station intact for examination was an objective. Hey, think the jamming of Chain Home that the Luftwaffe is able to do come August gets better after capturing this station intact? My guess would be that an intact functioning station in German hands is....bad...for the RAF? What's yours?



Any seaborne landing is in the south, and any attack on Cowes comes overland by road from the south.



No, the RAF is on the defensive, the Luftwaffe is on the attack. The RAF sucks at ground support and ship attack. The Luftwaffe is good at both. RAF 11 Group can attrite the LW in this battle, but it cannot stop the attack. British troops on and around IOW are going to be pounded by the Luftwaffe in heavy air attacks. You understand? It's the entire bloody Luftwaffe concentrated into one battle the size of Crete. The RAF doesn't "do" effective close air support at this time, and won't until it learns how in Africa later.



I think you might be underestimating the problem a bit.



A Channel convoy might be composed of three or four 200 to 1,500 ton scow transports, escorted by a scratch force of maybe a half dozen converted trawlers and such with heavy AA or light cannons up to 4", plus dozens of small MB's and such for picking up men in the water. Overhead, hundreds or thousands of LW anti-ship sorties going after anything RN that is attempting to intercept. Same thing. Every day. Can you see how after a few days the RN might conclude that losing 4 destroyers a day can't be sustained, just to sink 3 or 4 scows that can be replaced by hundreds of others? That's the power of coastal shipping tactics.



No, you don't understand the SLOC problem for the RN. "Barges" refers to massed shipping movement related to the transfer of entire armies at sea in one lift. A supply convoy is two or four small expendable ships, easily replaced, escorted by a half dozen small ships, also easily replaced, repeated one, two, three times per day, every day, under skies with the Luftwaffe overhead.



How did you arrive at the conclusion that the entire Luftwaffe committed to one small battle could not attack warships and provide close air support at the same time?



So answering 25 posts a day, now I have to relist all the stuff that's already discussed too? Pass. Bombing would have to be all the RN ports on the south coast, but heavier with Portsmouth. Primarily with twin engine types, primarily at night is the sketch.

You know the RAF doesn't have to waste time with CAS missions. The RN has plenty of ships that can do that across the Solent.

With respect to the Luftwaffe and attacks on the IOW / Cowes, ORP Blyskawica would like a word with you.
On the night of 4–5 May 1942, Błyskawica was instrumental in defending the Isle of Wight town of Cowes from an air raid by 160 German bombers. The ship was undergoing an emergency refit at the J. Samuel White yard where she had been built and, on the night of the raid, fired repeated rounds at the German bombers from outside the harbour; her guns became so hot they had to be doused with water from the River Medina. Extra ammunition had to be ferried over from Portsmouth. This forced the bombers to stay high, making it difficult for them to target properly. The ship also laid down a smokescreen hiding Cowes from sight. The town and the shipyard were badly damaged, but it is generally considered that without this defensive action, it would have been far worse.

Now that was the action of a single Polish DD in an ad hoc action when faced with 160 bombers. Now imagine how effective multiple prepared RN and allied ships would be defending Cowes from air attacks - and on bombarding any German troops that would be trying to advance on Cowes.
 
A Channel convoy might be composed of three or four 200 to 1,500 ton scow transports, escorted by a scratch force of maybe a half dozen converted trawlers and such with heavy AA or light cannons up to 4", plus dozens of small MB's and such for picking up men in the water. Overhead, hundreds or thousands of LW anti-ship sorties going after anything RN that is attempting to intercept. Same thing. Every day. Can you see how after a few days the RN might conclude that losing 4 destroyers a day can't be sustained, just to sink 3 or 4 scows that can be replaced by hundreds of others? That's the power of coastal shipping tactics.
Glenn please explain,
you see how after a few days the RN might conclude that losing 4 destroyers a day can't be sustained, just to sink 3 or 4 scows that can be replaced by hundreds of others?
You do realise that RN had more DDs than KM has "converted trawlers" or "small MB's" ?

That RAF has lots of fighters it will throw into the battle and its bombers that are now usefully unlike BoB as the LW fighters need to stop them attacking the convoy.....

Its not going to happen every day.... KM and LW will not be able to carry on after a couple of days and GB will happily accept losing a flotilla of DDs and equal numbers of aircraft for that outcome....

GB will also realise that in a few days of this the entire elite of the German airborne force will starve/surrender and this makes any future invasion of GB/Malta/etc impossible for years.....
 
by my calculations the luftwaffe would be able to have a continuous daylight cap of 12 fighters over the isle of wight.that should hold the raf back from attacking all those thousands of bombers destroying the rn.
 
The Coastal Batteries are on the mainland and cover nearly all of the Isle of Wight coastline

So....they would have to be captured by invading the mainland now?

I am reminded of that song "There's a hole in my bucket"

Hm, fair point. In order to Sea Lion the Isle of Wight, it may be necessary to invade Great Britain too, at least temporarily. Now what to call this secondary raid.... Need a good code-name....

GB will also realise that in a few days of this the entire elite of the German airborne force will starve/surrender and this makes any future invasion of GB/Malta/etc impossible for years.....

I know this looks superficially sensible but Glenn has already demonstrated to us conclusively that Britain would panic and race to the peace table the moment a jackboot struck English soil, so clearly your reasoning here is faulty. I just can't see where or how.

In my judgement only 5-10% will starve/surrender. This is an Objectively Arrived-At Statistic.
 
On a related note, did you know that many military disasters are caused by arrogant assumptions that overlook key details

Like the lack of suitable beaches for landing, or flat fields for your night aerial operations, or the fact that much of the island is within range of artillery which will interdict operations. Or the tides you overlook, or the massive disparity of naval forces which you dismiss time and again. Or the fact that the FJ are under strength after the battle of France, that "infantry trained on a few jumps and assembly" (your words) are not equipped for a night parachute landing in broken terrain and jumping out of planes not designed for that operation are hardly a crack force that can seize the island.

It's called Victory Disease. Grab a Ouija board and ask Yamamoto about it. He'll probably tell you that this thread is choked with the stuff.

Honestly, you shouldn't deride your own posts like that.

You ask how IOW might stand a small chance of snowballing into losing the war. Something like this -

Step 1 - Germany takes IOW an a massive surprise air/sea assault. Surprise is achieved, the local defenses are overwelmed, and reserves fail to act due to a series of small, diversionary landings elsewhere that absorb attention in the key 24 hour period.
Step 2 - The RN and RAF attempt, but fail, to interdict the LOC to Isle of Wight over the next 1.5 months. (A series of small expendable convoys run in daylight under massive LW cover, causing a meat grinder effect for the RAF and RN in the Channel between Cherbourg and IOW).

Assuming #1 which is already a stretch because there is no way you will achieve operational surprise with channel ports being watched by naval and aerial recon, and with boots on the ground reporting from behind those German lines.

#2 is absolutely ridiculous. The LW here is trying to protect its ships, apparently sink the RN before the supply ships are destroyed, and battling the RAF. None of which has to be done on the far end of the channel or even mid-channel. Those supplies have to come north of the IOW to the ports otherwise no heavy equipment reaches the island. That puts the luftwaffe on the far end of its reach, and we saw historically how a battle over the skies of Britain went for the Luftwaffe.

Step 3 - The British government, increasingly concerned that IOW is becoming an offensive springboard to seize Portsmouth and Southhampton, orders the British army to retake IOW by storm.
Step 4 - The British army strips a large chunk of its invasion reserves to retake IOW in September.
Step 5 - Sealion lands in the Dover area with British reserves diverted westwards. The landing is not contained due to lack of available reserves to contain it, and breaks out.

So who is protecting sealion 2? Your LW is heavily engaged over the IOW, the KM which has to supply those forces is taking losses it cannot replace, you've gutted your FJ forces, and regardless if the army has moved reserves south, Sealion still has to get past the Royal Navy, which guess what? Is still in the way and your 6 destroyers and tugboat powered barges of the KM are not going to make it.

Steps 1 and 2 were possible, (posters that suppose the RN, even with RAF cover, can go up against the LW in the Channel day after day are talking complete nonsense).

This is merely your assertion completely devoid of any factual backing. It would be nice if you actually had a factual basis for your statement, one that didn't rely on a single cherry-picked data point that you then stretch to a point that would give a statistician a heart attack.
 
The way airborne troops take Cowes is they land in the center of the island then move north into the city. Those coastal batteries they would try to capture intact from behind.
From the center of the island to Cowes is about 10k (or 6 miles). So they land, pick up their gear (which is dropped seperately), assemble and walk there (because they don't have jeeps, as the British landed at Arnhem in operation Market Garden). Don't you think the element of surprise would be kinda lost?

And indeed as @Cryhavoc101 noted the coastal batteries are partly on the mainland. So good luck capturing them.

Yes, the first hint that I realised that Chain Home was on Isle of Wight was the times when I said that capturing the radar station intact for examination was an objective. Hey, think the jamming of Chain Home that the Luftwaffe is able to do come August gets better after capturing this station intact? My guess would be that an intact functioning station in German hands is....bad...for the RAF? What's yours?
I thought you were insisting to take the IOW in july? Now it's august? In august there's more preparation from the British than in july. And how good did the jamming work? According to Wiki the first was installed in september 1940.

Any seaborne landing is in the south, and any attack on Cowes comes overland by road from the south.
So, again, where's the element of surprise? From the south it's an even longer walk than from the centre? And since you insisted they use the fast transports, they're gonna paddle in boats from their transport to the shore, so now heavy equipment or trucks.

No, the RAF is on the defensive, the Luftwaffe is on the attack.
I'm quite sure Bomber Command will bomb the captured airfields and beaches (and ports too, if they captured those) at night. Which is bad for your resupply. As I already mentioned before an airraid with 4 Fokker T.V's of the Dutch at The Hague caused damage to parked Ju-52s at the airfield. The RAF has a lot more and more capable bombers.
The RAF sucks at ground support and ship attack. The Luftwaffe is good at both.
I wasn't talking about CAS, but about bombing supplyzones. And in OTL they did bomb the barges in the french ports. I'm quite sure when the Germans are on the IOW, the RAF will bomb ports, airfields and beaches were the Germans are bringing their supplies. Simply because the most important thing is to repel an invasion.
The LW is not so good at attacking ships, as @Michele pointed out already.
RAF 11 Group can attrite the LW in this battle, but it cannot stop the attack. British troops on and around IOW are going to be pounded by the Luftwaffe in heavy air attacks. You understand? It's the entire bloody Luftwaffe concentrated into one battle the size of Crete. The RAF doesn't "do" effective close air support at this time, and won't until it learns how in Africa later.
Well, 11 Group did quite well against the entire LW in the BoB (again, @Michele posted the numbers involved).

I think you might be underestimating the problem a bit.
No, you are.

A Channel convoy might be composed of three or four 200 to 1,500 ton scow transports, escorted by a scratch force of maybe a half dozen converted trawlers and such with heavy AA or light cannons up to 4", plus dozens of small MB's and such for picking up men in the water. Overhead, hundreds or thousands of LW anti-ship sorties going after anything RN that is attempting to intercept. Same thing. Every day. Can you see how after a few days the RN might conclude that losing 4 destroyers a day can't be sustained, just to sink 3 or 4 scows that can be replaced by hundreds of others? That's the power of coastal shipping tactics.
That's been adressed before, by several posters. The RN has quite a lot of vessels too, which are way more capable than the ragtag 'armada' of the Germans.

And hunderds or thousands LW sorties each day? I thought you were using the two-engined bombers to resupply the invasion force. They can't do both. And they don't have that many Stuka's, who BTW don't do very well in contested airspace. In OTL the Stuka's were withdraw from the BoB quite soon, because they were decimated.

No, you don't understand the SLOC problem for the RN. "Barges" refers to massed shipping movement related to the transfer of entire armies at sea in one lift. A supply convoy is two or four small expendable ships, easily replaced, escorted by a half dozen small ships, also easily replaced, repeated one, two, three times per day, every day, under skies with the Luftwaffe overhead.
Well, a supply convoy is either going to sit in front of the beach, and then unloading takes awhile, and they most likely can't return in daylight. So the RN will be quite happy to pay them a visit then.
In the ports on the north side, they're in range of coastal artillery of the mainland, which is perfectly capable of hitting ships.
And if you say "ah, the coastal artillery is gonna be put out of action by the LW." Well a) that's not so easy to do and requires a sustained bombing campaign. b) such a campaign should be done before the invasion, and is a sure sign something is going to happen there.

How did you arrive at the conclusion that the entire Luftwaffe committed to one small battle could not attack warships and provide close air support at the same time?
Well, basically you are saying all the time it's a big battle. If the entire LW is committed, by definition it's a big battle, and this will provoke a response by the British, so they will also commit a large part of the RAF. They're not going to say "oh, that's a lot of planes, we better give up."


So answering 25 posts a day, now I have to relist all the stuff that's already discussed too? Pass. Bombing would have to be all the RN ports on the south coast, but heavier with Portsmouth. Primarily with twin engine types, primarily at night is the sketch.
And this will be a giveaway that around that area something will happen. Maybe they won't realise it's the IOW the Germans will be attacking, but I think the British will not just sit back, retreat and relax. They will consider possible options and take countermeasures.

A sustained nightbombing campaign will lead to losses. You're right the British don't have an abunce of nightfighters, but there's AAA, and besides that, there will be operational losses.
 
Step 1 - Germany takes IOW an a massive surprise air/sea assault. Surprise is achieved, the local defenses are overwelmed, and reserves fail to act due to a series of small, diversionary landings elsewhere that absorb attention in the key 24 hour period.
Step 2 - The RN and RAF attempt, but fail, to interdict the LOC to Isle of Wight over the next 1.5 months. (A series of small expendable convoys run in daylight under massive LW cover, causing a meat grinder effect for the RAF and RN in the Channel between Cherbourg and IOW).

I can sort of - sort of - buy Step 1. Unlikely, but with a lot of luck and some expensive diversions, not completely impossible - at least, to secure a fair bit of the Isle of Wight.

But I cannot buy Step 2. No way, no how. The German lodgment lasts a few days, tops. Any convoys the KM tries will not be expendable, but expended before they even make sight of the Isle of Wight.
 
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