So many reactions to respond to... I'll do my best.
Let me start by saying that what I have in mind is a Sealion in the Summer of 1942, after defeating Russia in 1941. This is not a rule - that's not up to me - but that's what I have in mind when I make these comments. So that means half a year of preparations in which production of all kinds of aircraft and naval transportation devices are being build. I would expect the Germans to prepare for the invasion for half a year, gathering information and drawing up extensive plans. This is all meagre compared to what the allies had in 1944 but as I said before, it doesn't have to be like D-Day. Germany could do with less.
They would have to do with less.
If they defeated Russia in a 6 month campaign, the Germans then have 3-6 months to transfer their aerial forces and prepare them for an offensive campaign (assuming a start to operations between March and June 1942).
The German army has 3-7 months to prepare, given that the latest date for the original Sealion was the end of September .
Compare this to the 2 years of planning and 18 months of preparation carried out by the Allies before D-Day, with a significantly larger economic base.
I've read many references to D-Day like destroying of infrastructure, controlling the skies, etc. I think D-Day is such an icon because it was so incredibly succesful! When you look at it, it was almost a walk-over. Now before you start throwing things at me, let just look at the numbers until the end of July: 50,000 dead out of 2 million men. On D-Day itself 2,500 dead, most on Omaha beach. So besides Omaha beach, D-Day was a walk-over. That's what excellent preparation and numerical superiority lead to.
D-Day was a success because of several factors.
1. The complete aerial interdiction of the Coetetin penninsula and Normandy, combined with complete aerial control
2. The complete control of the sea and supply lanes by Allied naval power.
3. The ability of the Allies to land 8 complete divisions in the first 2 HOURS of the assault (including 3 airborne divisions).
3. The fragility of the German defences (stiff resistance at only 1 of the 5 beaches).
Total D-Day casualties were around 11,000 (including 2,500 killed), while the Allied landed approximately 160,000 thousand troops.
But if only half of these advantages were there, I still think D-Day would have succeeded. Not one of the beaches was a failure, not one was evacuated. Even if the allies had just one or two beaches in their hands, they could stil have won the battle and go on to break out of Normandy.
The single greatest worry for Montgomery and Eisenhower was that the beacheads remained unlinked or 'reduced' on D-Day. If the Germans had reduced the beacheds from 5 to two, I suggest that the operation would of been called off on D +1, as the tactical picture for the German army would of been IMMENSLY simplified.
I don't see Germany achieving superiority in the air, on the ground or at sea. But I do see them having control. And I believe this would have been enough to succesfully invade Britain, hold the beaches and eventually break out and defeat the English.
Let's break this down to those three fields:
Air: if Germany ever had better aircraft than the British it was in 1941/1942 with the Fw 190 and Bf 109F, both of which were superior to the Spitfire V or Hurricane II. Spitfire IX only appeared in the late Summer and in small numbers. British hardly had any attack aircraft, they were stick Blenheims, Beaufighters, no Typhoons or Mosquitos.
With increased aircraft production - as said above - and with most aircraft pulled back from Eastern Europe and with better pilots than the British (because of superior training hours), Germany would have held the advantage in the air. With the British aircraft primarily attacking targets in the Channel and over the German held beaches, they would no longer have the advantage of flying over friendly territory. Naturally, the Germans would have had the advantage. After a while Germany would have broken the back of the RAF in a battle of attrition like it itself had undergone in 1940.
Operating over British territory, with the British calling the shots on interceptions and able to assemble and guide their forces uch like the Germans did over France in 1941, the Spitfire V would of been on a much more even footing with the 109F (which is roughly equal in quality) and the 190A4/5 (which is superior).
The Typhoon Ib was in operational service by the end of 1941 and there were seven squadrons operational with the type by the end of August 1942 (Nos 266, 56, 256, 486, 181, 182 and 609).
Similarly, the Spitfire Mk IX began entering service in July, and there were 4 squadrons (Nos 64, 611, 401, and 402) operational by the end of August.
The other advantage the British have is a more than tripling of the strenght of Anti-Aircraft command by the end of 1941 (figures taken from 'Ack-Ack', by General Frederick A Pile, Commander in-Chief of Anti-Aircraft Command):
June 1940 ADA Defensive guns
Heavy:
4.5 inch: 355
3.7 static; 313
3.7 mobile: 306
3 inch (obsolete): 226
Light:
40mm Bofors: 273
2 lbr: 140
20mm: 38
3 inch (obsolete): 136
Dec-1941:
Heavy:
4.5 inch: 476
3.7 static: 935
3.7 mobile: 465
3 inch (obsolete): 144
Light:
40mm Bofors: 1,056
2 lbrs: 71
20mm: 62
3 inch (Obsolete): 8
Plus, AACommand had introduced radar azimuth and ranging detectors, essentially doubling their effectiveness in terms of accuracy and battery fire control.
Oh yes, I forgot to mention that I do not think it would have been a good idea to start an extensive air offensive before the invasion. That would have failed for the same reasons as in 1940. Surprise would have to be on the German side: paradropping at night and landing the first wave at dawn.
And what happens on the second day, when an undiminished RAF strikes the German beachheads and the supply ships anchored of the coast waiting to unload?
Coastal Command is hardly impotent, with low level Hampdens, Bostons, Beaufighters and Whitleys to hit the Kriegsmarine.
The RAF is going to have a dream scenario carpet bombing the invasion beaches while Hurribombers go in at low level.
Sea: Although the Channel could not be sealed off, it could have been made difficult for the RN. Sealing off the Channel does not mean mining the Channel itself but the access lanes towards it creating a almost sealed-off area in which the Kriegsmarine and German transport vessels can operate. These mines will be dropped at night by subs and aircraft. (I just found out that wargames conducted at the Royal Military Academy Sandhurst in 1974 concluded that it would have taken a few days before the fleet would have arrived coming from Scapa Flow.) On their way they will be attacked by German bombers and submarines, and hindered by extensive mine fields and agressive German Kriegsmarine maneouvres.
You are forgetting serveral important parts of the British defensive plans: the light costal forces and submarines and the RNs own minfields.
The RN had approximatley 80-120 light coastal boats in Home Waters at any one time. Unlike their German counterparts, British light boats had radar and were trained to operate both at day and night. Anti invasion plans were to strike at the Kriegsmarines escort ships initially with Motor torpedo boats in the day (which were not as good as German E-boats) and then disrupt landing and resupply operations with Motor Gun Boats at night.
British submarine forces would of had a field day: tightly packed, slow moving assault craft guarded by destroyers while the big ships (crusiers and battleships) rides shotgun, attempting to picket the RN.
The Royal Navy will not be able to get to the Channel in strength on the first day and will offer itself piecemeal to all those hundreds of German Stukas and Ju 88s. When the main fleet will arrive from Scapa Flow the German divisions will have increased and have dug in for the awaited British assault, while being supplied by air. Although I see the RN cutting supplies for the German beachhead and attacking it, I wonder how long the Royal Navy would be able to witstand the damage German bombers will inflict on them? It will be a trade off between defeat of the Royal Navy or the defeat of the German invasion army. What will be easiest to rebuild? The Germans had a hundred other divisions... For that reason I don't think the Royal Navy will be holding out for longer than 2 days after which they will count their losses. 2 days in which the elite German divisions will have to hold out. I think this will be the defining moment and IMO it can go both ways, depending on the decision of the British leaders.
The RN had a saying around the battle of Crete "It takes three years to build a ship, it takes three centuries to build a tradition".
The RN may be damaged, even heavily, but neither the LuftWaffe or the Kreigsmarine are going to go home intact either.
The ability of the Luftwaffe to destroy the RN, while stationary and evacuating troops at Dieppe (6 destroyers over 10 days, including 2 torpedoed and one mined) and Crete (2 cruisers, six destroyers) seems a little overrated to me.
You haven't granted control of the skies to the Luftwaffe, and the RN would be operating in home waters, under the umbrella of an undiminished RAF operating over 100 squadrons of fighters. The RN would harely be prey to hordes of bombers.
More tommorow....
