Operation Sea Lion (1974 Sandhurst Wargame)

[Glenn239]

The main point that you have studiously ignored is that 1 count him, 1, German soldier from that convoy which numbered over 2000 soldiers managed to reinforce the German FJs already on Crete.

The Sandhurst game predicted about 60% of the 2nd wave barges sunk by the RN. Not held off, or forced to return to port, or scattered, or whatever else. Sunk.

And 50-100 hits - by 1000 sorties?

During Op Dynamo 6 British and 3 French Destroyers were sunk 4 and 1 respectively by air attack over 10 days and at least 3 of those were stationary or maneuvering very slowly at the time - so about 1 ship every 2 days

The PK of a hit by a Stuka dive bomber in 1940 vs. a destroyer underway is about 5%-10%. If 20 Stukas attacked a destroyer, chances were good they would get at least one hit.

And if the Stukas are focused on badly bombing the Navy then they are not doing any of the other jobs that the mission desperately requires them to do.

That's what the Sandhurst umpires seem to have been thinking, that the Luftwaffe should be busy doing what the Royal Navy wanted it to do rather than what the German players wanted it to do. Under optimal conditions a Stuka could do up to 10 combat sorties per day. Assuming good weather, RN warships challenging in daylight in the waters off Pas de Calais would look more like optimal conditions than marginal ones. Let's say that for giggles 300 Stukas manage 4 sorties each on average, and 500 JU-88's manage two each. In 2,200 bombing sorties, the expected result is 2 destroyers sunk by U-boats?

 

[ObssesedNuker]

That's what the Sandhurst umpires seem to have been thinking, that the Luftwaffe should be busy doing what the Royal Navy wanted it to do rather than what the German players wanted it to do.

Best I can tell, the Luftwaffe was doing what the German players wanted it to do. Which is that it was dividing it's attention among all of the missions it would have had to do IRL.

 

[Glenn239]

Technically the Luftwaffe wasn't bad at anti-ship bombing, it's just that sinking ships is harder then it seems. As the British are liable to come south as far as possible in the darkness, the Germans get only two, maybe three major attacks in before they're in among the invasion fleet. Keep in mind that even if the Luftwaffe has forced 11 Group to withdraw, the Home Fleet will still have air cover from 12 Group as they come south, so any longer ranged attacks by medium bombers escorted by only Bf 110s would be both less effective and very costly.

Luftwaffe attacks on RN warships obviously would continue - and even intensify - with the RN warships in amongst the invasion fleet. When the warships contacted the invasion fleet, they would have to go from AA formation (a tight ring) to line ahead or line abreast in order to engage sea targets. Once the AA ring formation was broken, the warships are considerably more vulnerable to attacking aircraft. Ships that lost power to damage would also become vulnerable to coastal artillery.

The RN probably waits for nightfall, then comes into the Channel. But if so, even if disrupting the reinforcement wave, I don't think they could score anywhere near 1,000 barge sinkings.

 

[ObssesedNuker]

Luftwaffe attacks on RN warships obviously would continue - and even intensify - with the RN warships in amongst the invasion fleet.

Sure, but it'll be too late then as the barges are already getting massacred and their as liable to hit their own barges as they are the warships. Also, my scenario make several assumptions to produce a best case for the Luftwaffe when in reality the Luftwaffe's resources are liable to be divided, the weather isn't likely to be so cooperative, and the stress of operations isn't liable to produce good historical norms so realistically the RN losses will be much less then what is produced in the best case. It's also worth noting that 74 vessels produced during the Sandhurst Games isn't even a maximum commitment the Home Fleet could achieve. If they sortie every single ship they have, which they are liable to do so as this is very much a "do or die" moment for the RN, there could be over 100 destroyers and cruisers screaming down on these hapless barges, plus the capital vessels.

The RN probably waits for nightfall, then comes into the Channel. But if so, even if disrupting the reinforcement wave, I don't think they could score anywhere near 1,000 barge sinkings.

Of course you don't, because you considerably overestimate the durability of the barges in order to further wishful thinking that even the Nazis didn't buy into.

 

[marathag]

Under optimal conditions a Stuka could do up to 10 combat sorties per day. Assuming good weather, RN warships challenging in daylight in the waters off Pas de Calais would look more like optimal conditions than marginal ones. Let's say that for giggles 300 Stukas manage 4 sorties each on average, and 500 JU-88's manage two each. In 2,200 bombing sorties, the expected result is 2 destroyers sunk by U-boats?

or we can look what the Stukas and Ju-88s from Fliegerkorps VIII actually accomplished over Crete, and then factor in the effect of Spitfires and Hurricanes being around to stop them.

 

[fastmongrel]

Some of you don't seem to realise the Sandhurst gaming wasn't one go. It was gamed iirc at least four times. One game was an absolute clusterfuck for the German side. The rules and starting positions were altered for subsequent games, one was the British Army and Navy wasn't allowed to bring in reinforcements the German force got halfway to London before they ran out of fuel and ammo.

 

[CV12Hornet]

The PK of a hit by a Stuka dive bomber in 1940 vs. a destroyer underway is about 5%-10%. If 20 Stukas attacked a destroyer, chances were good they would get at least one hit.

And the Germans only deployed 261 serviceable dive bombers against the UK in the Battle of Britain, so assuming they devote equivalent airpower they need 4 sorties per dive bomber just to get a bomb hit on every destroyer. That doesn't count the cruisers, which will need more working over than the destroyers, nor does it account for destroyers that will need more than one bomb hit to get knocked out of the fight. Four sorties, per Stuka, just to get one bomb on one destroyer, which may not even knock it out of the fight. And this doesn't count attrition, either.

I don't know what turnaround time on a Stuka is, but considering the Germans are on a clock here I'd be willing to bet four sorties per plane is entirely too many.

Now, you could toss in the Ju 88s, as they can do dive bombing, too, but then you start tossing in the British cruisers and the bite of attrition and the need to hit some of the destroyers at least twice and those extra airframes start looking increasingly inadequate.

 

[Not James Stockdale]

Of course you don't, because you considerably overestimate the durability of the barges in order to further wishful thinking that even the Nazis didn't buy into.

This is one of the questions in the OP. I know the 1974 wargame included roughly 1,500 river barges in the second echelon, but I have heard that there were documents discovered since 1974 indicating plans for a significantly larger invasion fleet and one made up of far more motorized vessels that probably would have fared better than unpowered barges.

 

[Mike D]

This is one of the questions in the OP. I know the 1974 wargame included roughly 1,500 river barges in the second echelon, but I have heard that there were documents discovered since 1974 indicating plans for a significantly larger invasion fleet and one made up of far more motorized vessels that probably would have fared better than unpowered barges.

Unless those vessels happen to include a decent number of battleships, cruisers and destroyers the barges are still going to be slaughtered by everything from armed trawlers to cruisers, the invasion will still fail and tens of thousands of surviving German troops will spend the rest of the war counting blades of grass in Canada and mourning their dead Kameraden.

 

[nbcman]

If battleships were not supposed to be in the English Channel, someone forgot to tell HMS Revenge as she was in the Channel in September 1940 and bombarded Cherbourg in October 1940 as part of Operation Medium. This fib about the RN not willing to risk BBs in the Channel has been told for years and has been shot down every time.

BTW - What German BBs? The German navy was a whole 1 CA, 4 CLs, 10 DDs, 2 BCs and 2 pre-Dreads of which most were damaged after the Norwegian campaign plus Bismarck who was still doing her sea trials.

 

[Glenn239]

Some of you don't seem to realise the Sandhurst gaming wasn't one go. It was gamed iirc at least four times. One game was an absolute clusterfuck for the German side. The rules and starting positions were altered for subsequent games, one was the British Army and Navy wasn't allowed to bring in reinforcements the German force got halfway to London before they ran out of fuel and ammo.

We're talking about one specific air sea battle during Sandhurst, where 74 RN warships sank 1,000 barges of the 2nd wave in the Channel in broad daylight losing 2 destroyers to U-boats in the process. Given that the Luftwaffe off Pas de Calais in September 1940 should have been able to generate thousands of anti-ship sorties in a maximum tempo effort, how did the umpires decide that no RN warships were lost to air attack?

 

[Glenn239]

This is one of the questions in the OP. I know the 1974 wargame included roughly 1,500 river barges in the second echelon, but I have heard that there were documents discovered since 1974 indicating plans for a significantly larger invasion fleet and one made up of far more motorized vessels that probably would have fared better than unpowered barges.

How is it possible that the Sandhurst umpires could not have access to the real Sealion OOB for its naval echelon?

 

[Cryhavoc101]

If battleships were not supposed to be in the English Channel, someone forgot to tell HMS Revenge as she was in the Channel in September 1940 and bombarded Cherbourg in October 1940 as part of Operation Medium. This fib about the RN not willing to risk BBs in the Channel has been told for years and has been shot down every time.

BTW - What German BBs? The German navy was a whole 1 CA, 4 CLs, 10 DDs, 2 BCs and 2 pre-Dreads of which most were damaged after the Norwegian campaign plus Bismarck who was still doing her sea trials.

In August 1940 - state of German Surface fleet

Gneisenau - Torpedoed - not ready before Nov
Scharnhorst - Torpedoed - not ready before Oct
Admiral Scheer - Refitting - not ready before Sept
Lutzow - Refitting - not ready before April 41
Admiral Hipper - Refitting not ready before Sept
Nurnberg - in Commission
Leipzig - Under repair - not ready before Nov
Koln - in commission
Emden - in commission for training duties
1 Van Reader Class DD - in commission
8 Leberecht Mass Class DD - 3 refitting
20 Torpedo boats (equivalent of a light Destroyer - 1 of which was still completing - ready for Oct (5 Moew class 1926-29, 3 Wolf Class 1928-29, 11 T.I. Class 1939) 1 of the first batch and 3 of the 2nd batch had been sunk before Aug 1940 there was originally 6 of each. 1 more T class ready for Oct
35 MTBs - of which 12 are refitting

So it's a total force of 3 Light Crusiers including Emden (which was a training vessel), 6 Destroyers, 19 Torpedo boats (Light Destroyers) and 23 MTBs

Just to put this into context - Operation Neptune in 1944 when the Allies were going the other way used 7 Battleships, 5 Heavy Crusiers, 20 'light' Crusiers and 193 Destroyers

 

[CV12Hornet]

How is it possible that the Sandhurst umpires could not have access to the real Sealion OOB for its naval echelon?

More WWII documents are discovered all the time. It's how books like Wages of Destruction get made: someone finds new primary sources, analyzes them, and comes to fresh conclusions. I am not surprised that hitherto undiscovered documents related to Sealion were dug up after 1974, they were probably shoved into a back closet somewhere in 1940 and between standard bureaucratic shenanigans and the devastation Germany suffered forgotten about.

 

[King Augeas]

The PK of a hit by a Stuka dive bomber in 1940 vs. a destroyer underway is about 5%-10%.

Sounds like nonsense.

 

[sloreck]

I have seen scenarios where destroyers moving at 20-25 kts create enough wake to swamp at least some of the barges, which I can certainly believe. The freeboard of relatively heavily loaded barges is not going to be all that much, and even if the seas are entirely calm this is going to be a problem. MGBs with 20-40mm guns are going to rip up the landing craft, even .50 cal will open up holes. Even navalized trawlers with .50cals will cause problems, if in no other way but chopping up the soldiers in the barges. You can dispite the absolute numbers, but after the first wave the number of seaworthy barges/craft available will be markedly reduced.

 

[Not James Stockdale]

I have seen scenarios where destroyers moving at 20-25 kts create enough wake to swamp at least some of the barges, which I can certainly believe. The freeboard of relatively heavily loaded barges is not going to be all that much, and even if the seas are entirely calm this is going to be a problem. MGBs with 20-40mm guns are going to rip up the landing craft, even .50 cal will open up holes. Even navalized trawlers with .50cals will cause problems, if in no other way but chopping up the soldiers in the barges. You can dispite the absolute numbers, but after the first wave the number of seaworthy barges/craft available will be markedly reduced.

The additional German shipping that I'm trying to find information about was apparently supposed to include at least 250 armed auxiliary vessels to counter the threat of British MGBs and trawlers. The German invasion fleet certainly would not have been as undefended as you seem to be implying. What I have seen about the Sandhurst game also says that the German tactical aircraft continued ground support and counter air missions over Englnad instead of supporting the second echelon fleet. The impact of second-line American aircraft armed with GP bombs, depth charges, and machine guns against the Japanese battlefleet off Samar (accounting for two of the three heavy cruisers that were sunk) indicates that almost any aerial presence over the British counterattack would have been significant given the effectiveness of 1940 naval AA. Also, given the fact that the British surface force would have been approaching at top speed along entirely predictable attack vectors, I seriously doubt the apparent lack of tactical impact that the German U-boats exhibited.

 

[hipper]

The additional German shipping that I'm trying to find information about was apparently supposed to include at least 250 armed auxiliary vessels to counter the threat of British MGBs and trawlers. The German invasion fleet certainly would not have been as undefended as you seem to be implying. What I have seen about the Sandhurst game also says that the German tactical aircraft continued ground support and counter air missions over Englnad instead of supporting the second echelon fleet. The impact of second-line American aircraft armed with GP bombs, depth charges, and machine guns against the Japanese battlefleet off Samar (accounting for two of the three heavy cruisers that were sunk) indicates that almost any aerial presence over the British counterattack would have been significant given the effectiveness of 1940 naval AA. Also, given the fact that the British surface force would have been approaching at top speed along entirely predictable attack vectors, I seriously doubt the apparent lack of tactical impact that the German U-boats exhibited.

The german plan involved loading the barges on S-4 then moving them along the coast untill S-1 where they sail across and “suprise the british” there would be several nights of slaughter as the loded barges were hunted down each night with a big final battle off Calais after dusk on S-1.

in the only engagement of the war when a (small) german barge convoy tried to go through the Dover straits it was destroyed by RN destoyers after ilumination from Maritime patrol aircraft craft with Radar.

 

[GDIS Pathe]

The additional German shipping that I'm trying to find information about was apparently supposed to include at least 250 armed auxiliary vessels to counter the threat of British MGBs and trawlers. The German invasion fleet certainly would not have been as undefended as you seem to be implying.

250 Armed auxiliary against some ~700 British equivalents and some ~40-60 British destroyers and Cruisers? I don't like those odds

at I have seen about the Sandhurst game also says that the German tactical aircraft continued ground support and counter air missions over Englnad instead of supporting the second echelon fleet. The impact of second-line American aircraft armed with GP bombs, depth charges, and machine guns against the Japanese battlefleet off Samar (accounting for two of the three heavy cruisers that were sunk) indicates that almost any aerial presence over the British counterattack would have been significant given the effectiveness of 1940 naval AA

Didn't Taffy Three have the equivalent of some 300 aircraft in support? More than the entire Stuka force available for Sea Mammal? Crewed by naval aviators who are trained to attack ships and not ground pound? Against a force that had been under heavy air attack for much of the week? OTL US pilots flying SBDs missed some 70% of all bombs dropped at Midway this being pilots who are specially trained to attack naval targets. How do you think your average Stuka pilot with no training in attacking surface ships are going to fare?

Also, given the fact that the British surface force would have been approaching at top speed along entirely predictable attack vectors, I seriously doubt the apparent lack of tactical impact that the German U-boats exhibited.

A submerged German U-Boat has a top speed of around seven knots if the British surface force is racing south at top speed that means they're moving at around 20-30 knots and also probably making some evasive maneuvers of their own and have probably been doing this at night which means the U-Boats are likely struggling to keep up let alone get a firing solution

 

[marathag]

A submerged German U-Boat has a top speed of around seven knots if the British surface force is racing south at top speed that means they're moving at around 20-30 knots and also probably making some evasive maneuvers of their own and have probably been doing this at night which means the U-Boats are likely struggling to keep up let alone get a firing solution

The big Liners like Queen Elizabeth didn't Convoy against U-Boats, at 26 knots the U-Boats had only a short time to make a firing solution

another point, U-Boats stooging around in the Channel isn't a safe place to be, that's what the FAA was looking for