Indeed I read in one US document that by early September the KM was complaining that they were behind schedule in their mine sweeping for Sea Lion because of insufficient LW support.

One of the major points of the invasion plans was the demand by the KM that the Luftwaffe gain complete air control of the Channel for a period of 3 weeks to allow the setting up of the defensive minefields and the clearing of the British minefields.

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if in doubt....Panic!!!!

It is the duty of the Royal Navy to protect the United Kingdom at all costs, nothing else matters.

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if in doubt....Panic!!!!

Admiral Cunningham, 1941. (it was actually about withdrawing from Crete, but I think it's relevant.)

And anyway, if the Invasion was stopped there would be no need to evacuate the government.

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OK playing the devils Advocate here

From what I've read that Sandhurst game was fabricated by a newspaper editor to increase newspaper sales. It was developed to produce an end result, more sales. That would not have worked if the Nazi won.

On the face of it the German Norway invasion should never have happened while RN was supreme. It did because the Brits never believed they would try so made little prep for such an attack. When it came they completely misread the signs believing it to be another break out attempt by German battleships/Panzerschiffe. Admiral Raeder based his entire Norway on a hunch this would catch the brits completely by surprise, so he ordered his battleships to lead the RN away after escorting the invasion group. It worked the Brits were paraniod about German warships attacking their precious convoys.

I read on some of those websites that they hoped to do the same thing for Sealion, but only had a heavy cruiser and panzerschiff to lead the home fleet astray...wishful thinking? Churchill mircomeddled his way through the war, so I would not rule that out.

For the Norway invasion the Germans mounted a punitive airstrike on Scapaflow prior to sailing. This resulted in three raids , the first two raids of 10-20 planes hit nothing , but the third hit a Battleship a cruiser and straddled three more cruisers, with 24 bombers. With GPbombs they would only damage the battleship but these bombs could penetrate the deck of cruisers and put them out of operation. A raid weeks earlier had scattered the Home fleet, so air power was always a concern and KG 100 was getting better at hitting ships. Who knows but had they organised some torpedo bomber gruppe they could have crippled several capital ships at Scapa flow even if the torpedos were soooo bad.

Sifting through sources from both sides its clear both sides suffered from wishfull thinking. Level bombers like those used by the RAF were no good at sinking sea vessels, so the Brits can't expect to much from them. I read somewere that Churchil comissioned one of his scientists at the end of 1941 to figure out why they were getting no were bombing german. That scientist reported back that 2/3 of the RAF bombers were missing the target by atleast 5 miles! Some were else reported that RAF averaged 150 missions to sink a ship and that channel dash some one refered to they flew 600 missions and sunk only one escort vessel

As to German intelligence it does seemed to have overestimated British strength. Inital reports put the Brits at 38 divisions when the real number was 1/2 that. Worse the British commander figured that only 1/2 of his divisions were any good. The first German wave would have landed nearly a dozen divisions of which 9 divisions faced 4 British divisions, but the Germans thought they were facing 6 or more. So each front line infantry division was heavily reinforced with a tank battalion , SPAT companies and extra heavy artillery batteries and 10cm cannons plus a Neblweffer[sp] battery and extra engineer battalion + extra recon battalion. Supposedly 1/2 of this force would land and be operational two hours later, while the complete divisions would take days to be ferried across, with the corps completely transfered over two week period , including Luftwaffe flak regiments. So they would be able to defend themselves.

While the British had done a great job rebuilding the divisions with troops from dunkirk evacuations, alot of these troops were rear area troops and not combat troops. The combat troops ended in the strategic reserve of 1/2 dozen mobile divisions [2 of which were tank]. Its one thing to creat an army division, its another to make if fighting fit. I think it would be wishful thinking to expect these new divisions to fair well against the veteran German divisions. This is especially true since the British had not figured out the key to German success.

Mines are a difficult thing to measure, but the germans had planned to erect barriers either side of the invasion corridor with up to 12,000 mines , although 1/2 would be for destroying mine clearing devices. Some one noted that in Russia in 1941 such a barrier was penetrated in the Baltic and it cost them one ship out of every three that tried to break through.

One more note. Alot is made of naval supremecy based on sheer numbers. Many people quote 10:1 destroyers, but looking closer at the fleets , the German destroyers were much bigger than the British destroyers while some of the German torpedo boats were similar to British Destroyers designed in the 1920s [which I'm told made up nearly 1/2 their fleet]. Whats a destroyer and whats not a destroyer? If you add those the ratio is 5:1. In addition Some of the British warships were Norwegian and French torpedo boats , while the Germans also had some of these boats. Some sources include the 1000 ton Hunts as RN destroyers, but if thats true the 1000 ton German torpedo boats should be included? Finally some of the German torpedo boats were old from WW-I built before WW-I [1910?] and are generaly dismissed, however up to 1/3 of the British Destroyers were built during WW-I and would only have been 5-10 years younger than the German warships. Both were overhauled inbetween wars and used in secondary roles through out the war, should they be counted too?

warfare always comes down to the human element so I can never understand how people believe impossible etc. If the British gass the Germans on the beaches wouldn't that motivate the Germans to fight even harder since the standard fear mongering prewar was visions of hundreds of bombers flying over each country droping posion gass on each others population

Wouldn't it be a simple matter to (with corridors with mines on either side) say,...drop mines in the corridor ? Gauntlet ? Dead End ? Maneuverability would not exist. Targets for MTB's, submarines, aircraft ?
Your scenario is scary, but you assume the Germans have the boats, launch (with no loss of any boats)(even in the proposed "ant-like" supply chain)(what a wonderful target), get ashore (totally organized/supplied/unopposed), the weather is good (in the Channel), their navigation is perfect, they swept the existing mines (unhampered), fooled/scared the entire Home Fleet, and subdued the RAF.
A big leap forward.
As you say people are people, and they screw-up. All sides. So all the Germans would have to do is throw 7 or 11, about 8 times in a row, while England (in turn) would have to throw Box-Cars, or Snake-Eyes 8 times in a row.
I believe the German plan was on a "Shoestring" as it was. Their bet was that literally "Everything" was going to go right.
Has this ever happened ?
Saber Rattling, Scare Tactics, we have the upper-hand so you will do/give us, as we wish or else yada yada.

Big "Raspberry" !

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There's one way to find out if a man is honest-ask him. If he says "Yes", you know he's a crook. Groucho Marx

just one more (obvious) consideration about the morale on both sides.

remember that the nazi would attempt the invasion only if they had won the BoB against RAF. So that, the british morale in case on invasion would be very low, feeling like they were facing an invincible enemy, especially the luftwaffe .

When the BoB began british morale low, it got higher and higher as they were winning in the air.

i mean, it is wrong to project the psychological situation of september '40 to a totaly different scenario.

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If Hitler invaded hell I would make at least a favorable reference to the devil in the House of Commons
- Winston Churchill

Morale would have been different had the RAF been defeated by the LW. The point that is missed is that while Sea Lion might have been difficult it was possible, Had the BoB gone the other way (ie Hitler had not messed with it) then the RN would have been attacked, then the invasion. The Germans were not a completly inept race, they knew what needed to be done prior to invasion. Yes there was a general lack of shipping to move the whole German army, but there was enough to move 4, 5, or more. With little RAF or RN resistance, this now becomes a possible scenario.

Had BoB been won by the LW and the RN destroyed, the idea that the British would fight on the beaches, and in the cities, and everywhere, would have had to be revisited. Not that I think the British should have surrendered.

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The LW was loosign the BOB with or without "Hitler messing with it". Furthermore the LW simply could not win the BOB if you consider winning reduceing the RAF to the point where they couldn't interfere with Sea Lion. Dowding had already figured out the danger of that and would have withdrawn the RAF from Southern England to pretect them from further attrition if it reached the point where this was likely. From there they could redeploy to Southern England or fly from where they were to interdict Sea Lion.

As for high level bombers. There is a big difference between attacking well defended ports or vesels moving at relativly high or even moderate speed. Much of the invasion force would have been traveling at less than 6 knots in a fairly dense formation. Tugh boats and barges wouldnt hold up well to even a single 100lb bomb so dumb luck would favor the bombers in this case.

Now as to the Invasion forces take a look at:
Axis History Factbook: Order of Battle for Unternehmen Seelöwe (Sep 1940)
The first wave was to be composed of 9 divisions and I believe the Germans planned on it takeing 10 days to get them all ashore. Furthermore if you look into it in more detail you will find that they would not have been landing the entire divisions but a lot of their heavy weapons and transport would not have landed with the first wave. Note that there is little if any armor in this wave. The armor to be landed later for the most part counted on capturing a port iintact. The Germans also had very little in the way of engineering assets to get port back in operation and clearing the defensive mine fields in the face of British coastal batteries would have been a real challenge.

Again I encourage you to look at the numerous threads on the axis history forum. Both the Western Europe and What if subforums have had numerous lengthy discussions on this with a lot of backgound info (the BOB thread in the what if section has almost if not as much on Sea Lion as it does on the BOB).

I'm not saying that the Germans or anyone else are dumb as a race. In the case of the Germans....anything but. Probably why they didn't do it.
I am saying that the sooner they stopped listening to Georing and his grandiose claims...to destroy Dunkirk by air, resupply Stalingrad by air, support Kursk by air, and destroy the RAF and bring England to her knees by air, the better off they would've been.
With that "guy" (in charge)...you really need a plan B.
He did ask way too much of his Luftwaffe. Destroy the RAF, soften the invasion beaches, support troop advances, tow gliders, drop Falshirmjagers, sink the Royal Navy, and all at the same time.
Even if the planes he had never ran out of gas, (gun) ammunition or bombs, he'd still be hard pressed to accomplish all that.
The Kriegsmarine as it was, I don't believe could have fooled anyone (in the RN-except shadowing vessels) into leaving their very home undefended. They hugged the coast, hid in port, and took the long way round for a good reason. Those that didn't either blew themselves up (Graf Spee), rolled over in port (Tirpitz/Lutzow), or settled to the bottom...after being wounded (Gneisenau/Scheer/Hipper), or sunk in a fair fight (Blucher/Bismarck/Scharnhorst). The threat was neutralized.
I believe the RN was "Chomping at the bit" to get some real targets in front of them. Ah the wait was probably worse than anything else.
I don't see how the RAF could have (totally) lost the BoB, against short range fighters and 2-engine bombers. Shortsightedness in this area wold have overlapped into the invasion participation/support.

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I've looked at some of these 'Axis' sites and they are good but lack sources, so not sure on the details. For example each front infantry division was to get tank 'detachment' of > 40 tanks. This is strickly speaking not a 'battalion' since those were about 90 tanks, but instead a 1/2 battalion. So 4 battalions = 8 detachments or roughly one per division. Each division had assiged a SPAT company but in some cases they got assault gun battery instead.

From what Ive seen of early german WW-II campaigns they seemed chaotic to extreem , but this masks their doctrine which was very flexable in its employment. For example on the last day before Invasion of Norway, a parachute company was restasked from one mission/location to another without warning and carried that mission out, while none of the troops sent to Norway had more than a couple of days warning or any special training. They excuted the constantly shifting mission as required. So yes most German operations rarely go according to plan, but their command method was sufficent flexible to change directions in a matter of minutes if the need arose [with diminishing capability and consquences]. Messy yes, but they got the job done, in a way western armies could never have done at that time.

The Germans planned their landing not possesing any ports , this had been their conclusion from amphibious studies from the 1920s. It was all based on ship to shore landings...something the allies would learn in Normandy years later.

The Germans had 14 civilian mine layer ships set aside for the mine laying operations and these were extensions to existing mine fields that both sides had laid since the start of the war. I note that while the German 12,000 mines were to bridge gaps in barriers covering 40-60km , maybe 100km total, British mine laying was to be 3000 mines laid along 1/2 the English channel [ ~ 200km]. So the density of the German minefields were order of magnitude denser.

Looking at some of these Orbats the British had little or no minesweepers and had to retask a number of destroyers as duel role minesweepers. Backing this up were 750 newly converted minesweepers from fishing boats fleets. Due to the needs of rotation to continuously fresh vessels, only 550 would be available. But the south coast would have 400 of these and alot were to be sub chasers, so not clear how many would be clearing mines? Aparently only 1/3 of these trawlers were armed with guns, most just had machineguns.

Germany had atleast 70 minesweepers available, but not sure about how many were assigned to Sealion? In addition like the British they had hundreds of converted trawlers, that filled minesweeping missions, but all had guns, AAA and depth charges etc. One of those Axis sites puts the German fleet at 4000 vessels [barges etc] and 300 naval vessels, although the poster admitted that only 2/3 of that would be in the first wave, with the rest still assembling. Sinking ships fast enough to make a serious dent in such a force would take alot of time. Warships were not that good at sinking other ships in open seas, atleast not at that scale.

Similarly British warships were not any better than their German counterparts. Infact the tally of ships lost or sunk favored the Germans through the first years of the war, despite the fact they were so heavily outnumbered. With regards to level bombers, if their CEP realy was 5 miles, a target moving at 4knts as opposed to 10 knts, will make little difference.

One final point. If you look at nazi campaigns, they never required airsuperiority prior to launching any attack. This was done in step with the other service branches. From what I can see it was their idea of 'combined arms'. Looking at Norway operation the LW filled in where navy or army failed..etc. The conditions to initiate the first steps in the invasion , already existed by early September 1940.

The decision to go or not to go was a political decision, based on poor intelligence. The British had far fewer divisions than the Germans thought and it was becoming apparant the German shipping was unable to ship the number of divisions required at the rate needed. In addition the initial British counter attacks on the barge fleet were much less effective than first thought. Highlighting a danger that the Navy had warned Hitler about from the start. On top of this failure of the LW showed up the poor intelligence on enemy losses. All these factors combined and Hitler lost all confidence in the mission . The last thing he needed was a failure in the face of his fear of America. Hitler never really understood the real capabilities of his own military forces.

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Some of the forum posts are pretty good as far as references. Some of the threads have gotten fairly acrimonious and as a consequence sources were called for and produced and discussed.
This is from memory of the discussions there but I believe the tanks to be landed were all lighter ones. There were a few that could swim but most could not. Furthermore they were going to be very short on motor transport, artillery, and artillery ammo in the first wave. On the beaches a lot of the artillery deficit was to be made up for with guns mounted on the barges. However the one documented German landing experiment with the barges showed some significant problems.
Again from what I've read they had no capability to put an armored division ashore over the beaches. The 2nd wave in particular the armored divisions required capturing a port. The allies at Normandy were well versed in how to conduct a seaborne invasion. That's why they had the Mulberrys.
The mining situation has been well discussed over there. The Germans were way short on mines to do the required mining. They were also short on mine layers and furthermore if you take a close look you will see that a considerable number of German ships were mine layer/sweepers. The plan seams to have required these ships to do triple duty (lay mines, sweep mines, and escort the invasion fleet).
I suspect your Orbats are either out of date or don't consider all the small mine sweepers the British had. Due to the German campaign mining the British ports they had quite a bit of sweeping capability by September. Again this subject has been covered in detail on the axis history forum.
4000 seams awfully high. From what I've read the Germans evaluated about 3000 barges (some self powered) of which a significant number were determined to be unseaworthy. I believe that the first wave was to consist of about 1500 along with all most if not all the tugs. The naval vessels were all small combatants or support ships. Most of these vessels would have been vulnerable to even heavy machine guns. British DDs did pretty well vs such a force off Crete.
Let's start at the top.
British BBs ranged from better to on a par with German BBs however the only German BB was a coastal defence BB and vastly inferior to even the British BCs, so the British have a huge edge here.
German CAs were superior to British CAs however only one was available. The British had several available.
German CLs were inferior to British CLs and the only available ones were scheduled for diversionary activities.
British DDs were at least a little better than their German equivalents and there would have been a lot more of them.
German E-bats were significantly better than British MTBs but the British had more again.
Small combatants and converted civilian craft highly variable but roughly equivalent and again the British had a lot more.
Also consider that the Germans had minimal ASW assets. While there weren't a huge number of British subs there also weren't a huge number of decent sized cargo ships but these were to carry a lot of critical cargo (heavy equipment, ammo, and such) and would have been the natural target of the subs.
Given that the Germans planned on taking 10 days to unload the first wave thats a lot of exposure to both the RN and the RAF with a good number of vessels either sitting at anchor or steaming in circles at slow speed.

As for the CEP of the British bombers I believe the number you quote is for night attack. Even if it's not a big problem of early bombing campaigns was target identification. The heavy flak guns around targets particularly ports also tended to force the bombers up higher. An invasion fleet like this would represent little challenge in the way of target recognition. Furthermore while there was a lot of light flak on the invasion fleet there wasn't much heavy flak and what there was would not be nearly as accurate, as coordinated, or as well supplied with ammo as ground based AA near or in cities.
The only seaborne invasion they launched they had effectively air supremacy over the critical areas and they had problems in the location(s) they didn't. The LW was over tasked by a factor of n (where n is some number >3) for Sea Lion. They had to:
1) Protect the invasion fleet
2) Interdict the RN
3) perform deep interdiction
4) suppress the RAF
5) provide close support
They had problems just performing 4 during the BOB. An already depleted LW would be starting in the hole trying to do this. Even without combat losses they would have had a hard time sustaining even the facade of an attempt to do all this (operational losses alone would attrit them severely)
It may have been a political decision but it was based on sound military thinking. The German military was far from convinced that they had any chance of success and some never took Sea Lion seriously. Trying to launch such an invasion into the face of an enemy who had a superior air force, a superior navy, and would have a superior army on the ground would have been suicide.

With regard to an invasion....The Fuhrer had not so far uttered any such intention, as he is fully aware of the extreme difficulties inherent in such an operation. That is also why the High Command had as yet undertaken no studies or preparations (the Commander-in-Chief, Luftwaffe, has put certain things in hand, e.g. the activation of a parachute division).
17 June 1940: General Jodl's Assistant to the German Naval Staff

The Fuhrer has no intention of mounting an invasion....There wont be any invasion, and I have no time to waste planning one.
25 June 1940: General Hans Jeschonnek, Luftwaffe Chief of Staff

We have here the paradoxical situation where the navy is full of apprehension, the airforce is very reluctant to tackle a mission which at the outset is exclusively its own, and OKW-which for once has a real combined operation to direct-just played dead. The only driving force in the whole situation comes from us. But alone we can't swing it.
6 August 1940: General Franz Halder. Chief of Army General Staff, on Operation Sealion.

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Well they still had the Tirpitz and Bismarck then.

The time period discussed is Summer 1940.

The Bismarck was commissioned 24 Aug 1940. I doubt it would be ready to participate in any operation until Autumn of that year.

The Tirpitz was commissioned 25 Feb 1941.

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JW