Could Operation Sealion really have succeeded?

That's right and there was no such thing as a trained night fighter, much less night fighter-bomber in 1940. For an operation like this, they wouldn't even need to commit the larger ships. The destroyers and lighter craft alone could have destroyed any invasion hopes in one swift night raid. Then they had four submarine flotillas in home waters in 1940 - can you see that concentrated in a small body of water and imagine the odds against any large German vessels?

I just don't see it happening, control of the air or not. The German high command must have realized the same thing.

 

Yes, but Germany had incredible pressure on Luftwaffe doing the job, perhaps Göring promising again more than he could deliver...

Anyway, check the article. It says that the RN would have at the latest destroyed the second German invasion "fleet" to supply the invasion troops on beach. End of German invasion. Personally I quite agree.

The only true way to get to invade would have been immediately following the Sichelschnitt operation/Dunkirk when Britain was not ready and in shock of the defeat in France. But Germany was even amazed of victory in France so they had no plan and no troops and no equipment to do that. However, if the Hurricanes had been sent to France when the war was getting lost what would have happened to Dunkirk as I understand that the RAF made a big difference to saving the troops back to Britain even though smoke and clouds made the Luftwaffe lose its sight of its target,too, for several days.

 

They were redirecting the tanks to the delta, because it was already understood, that any invasion was unlikely to succeed, and that the only reasonable chance the Axis powers had of defeating the Commonwealth, lay in seizing the Suez.

War Cabinet August 1st:

"The Prime Minister said that our position was now considerably more secure than it had been some two months earlier."

War Cabinet Minutes of Meeting: on the 13th of August:

"THE PRIME MINISTER gave his colleagues an account of his discussions with General. Wavell, Now that we were so much stronger, he thought that we could spare an armoured brigade from this country. He had asked the Firt Sea Lord if he could pass 2 armoured regiments (i.e. a light tank battalion and a cruiser tank battalion through the Mediterranean on two fast motor transport ships, in conjunction with Operation "Hats", The Prime Minister said that, later he had thought it would be a pity not to send a third armoured regiment of infantry tanks. He had asked the Chiefs of Staff to look into the matter, but they had thought that it was too risky to send M.T. ships through the Mediterranean, and proposed that the force should go round the Cape. "

War Cabinet Minutes of Meeting on the 31st August:

" THE SECRETARY OF STATE FOR AIR said that nothing in the fighting of the last few weeks had shaken the conviction of the Air Staff that we could hold our own in the air battle of 1940. We must therefore take a long view and consider our pre­ parations for the air battles of 1941."

On the September the 2nd:

"THE FIRST SEA LORD said that the indications pointing to invasion had never been more positive than they were at the present time.
THE SECRETARY OF STATE FOR WAR said that he agreed with this view,"

Once the scare of the 15th of July had receeded, the UK became increasingly more secure, as each day passed.

A Memorandum of the 18th July:

"These men would no doubt be sufficiently equipped to keep them going for some days, and possibly weeks, but, as mentioned above, the maintenance of their line of supply, unless the German air force had overcome both our air force and our navy, seems practically impossible."

 

I did some internet digging about this 2003-2004 and found something, unfortunately the site does not exist but it seems that the Germans might have tried the Sealion with barges in minor scale:

[SIZE=small]The exercise for Sealion in Boulogne:

(to my knowledge Hitler and Raeder were present )

Operation Sealion - The One Exercise
One single main exercise was carried out, just off Boulogne. Fifty vessels were used, and to enable the observers to actually observe, the exercise was carried out in broad daylight. (The real thing was due to take place at night/dawn, remember).

The vessels marshalled about a mile out to sea, and cruised parallel to the coast. The aramada turned towards the coast (one barge capsizing, and another losing its tow) and approached and landed. The barges opened, and soldiers swarmed ashore.

However, it was noted that the masters of the boats let the intervals between the vessels become wider and wider, because they were scared of collisions. Half the barges failed to get their troops ashore within an hour of the first troops, and over 10% failed to reach the shore at all.

The troops in the barges managed to impede the sailors in a remarkable manner - in one case, a barge overturned because the troops rushed to one side when another barge "came too close".

Several barges grounded broadside on, preventing the ramp from being lowered.

In this exercise, carried out in good visibility, with no enemy, in good weather, after travelling only a short distance, with no navigation hazards or beach defences, less than half the troops were got ashore where they could have done what they were supposed to do.

The exercise was officially judged to have been a "great success". [/SIZE]

[SIZE=small]---------[/SIZE]

[SIZE=small]the site not available anymore...[/SIZE]

[SIZE=small]http://www.flin.demo...thist/seal1.htm[/SIZE]

 

That exercise ALSO indicated that the alterations to the barges rendered them far stronger and more seaworthy than the specifications issued by the Kriegsmarine, and that they could now handle quite high sea states and gale numbers! See Schenk on this.

Regarding the Royal Navy and early ENOUGH warning....."Aye, there's the rub..."

Their Lordships warned on several occasions, including right through August, that they could not guarantee spotting the departure of any invasion fleet from Continental ports, or their interception at sea. There were several problems...

1/ they had sortied nightly destroyer patrols through late June and July, but the need for the destroyers used meant that these were stepped down to every second night after that. They also do NOT seem to have been mounted when the weather was at all bad - allowing the crews and ships some rest from that duty - but also permitting the Germans quite a bit of leeway of action in Continental waters. The KM was able to move barges forward to embarkation ports along the coast, and move minelayers, T-boats etc. to their intended ports without being intercepted by the Royal Navy. There was IIRC only one (1) occasion when invasion shipping was intercepted in transit - and none of the Sealion minelaying vessels or their screening escorts were ever intercepted either while laying the few minefields that WERE laid in UK coastal waters; there was an attempt to sortie destroyers from Plymouth to intercept a minelaying group and its escorts in Falmouth Bay, but although the destroyers sailed, they didn't ever find the KM minelayers or escorts.

2/ Much like the lines of tuna boats that the USN used to give physical early warning of enemy shipping off the West Coast and the approaches to the Panama Canal Department in the months after Pearl Harbour, the RN's Auxiliary patrol DID mount a picket line of armed fishingboats and yachts in the Channel etc., but their efficacy depended on visibility on the night - and visibility of their signalling rockets onshore

3/ A lot is made of RN destroyers having radar at this time, especially when patrolling at night along the coast of Occupied France and the Low Countries....but this was forward-facing radar, and there are a couple of instances of KM minelayers moving from port to port behind RN destroyer patrols after they had passed.

The Admiralty realised that while THEIR spotting of any invasion flotilla(s) wasn't quite as bad as looking for a black cat in a coal cellar...there were very major holes in their possible reconnaissance and interception capabilities....

REAL early warning of invasion forces having departed from their Continental ports would come each morning from the aerial recce sorties flown by the RAF. But these too would have been vulnerable to visibility issues over their "targets" - and would only show that the gathered invasion shipping had departed - not where it actually was when its ports of departure were photographed after their departure....or of course exactly where they were heading

 

It's also worth remembering exactly what the Royal Navy mustered for anti-invasion duties....c.36 destroyers in three flotillas of approximately a dozen, each with a cruiser or light cruiser flagship. Initially stationed in the Medway, Dover and Plymouth/Portsmouth IIRC. the Dover contingent was moved from Dover to the west after taking losses in the Channel.

Forbes at Home Fleet refused point blank to countenance bringing his capital ships south of Great Yarmouth and into the Channel Narrows....which refusal ultimately led to his removal. Capital ships needed both decent depth under their keels, AND considerable sea room for manouvering....to avoid fall of shot from coastal fire AND aerial bombardment Destroyers...well trimmed....could manouver relatively tightly - but not capital ships; in the Narrows they would have been stuck in the deep water channels, the modern day shipping lanes mid-Channel,....AND would only have been able to use half the width of the Narrows anyway because of the Germans' rapidly-positioned coastal guns. Again, see Schenk on this; on one occasion they managed to drive off the decent RN attempt to bring capital ships to bear on invasion barges in harbour.

Yes, RN destroyers COULD operate in daylight - but would they??? Events off Norway had demonstrated amply that in an environment dominated by enemy air power...remember, Sealion wouldn't even have begun if the Luftwaffe didn't enjoy air superiority over the invasion area ....even fast destroyers had to spend so much time and effort zigzagging and manouvering to avoid fall of ordnance that they could do very little else. A destroyer weaving around like a mad thing trying to avoid being bombed, and using ALL its armament to defend itself...isn't going to actually be able to do much against invasion shipping too! And for all its efficacy, Norway....and Dunkirk....had demonstrated too that manouvering to avoid fall of ordnance was not foolproof.... The RN had already taken quite a loss to its destroyer numbers since the start of the war...

See Brian Lavery's We Shall Fight On The Beaches regarding this; he also makes the very important point that due to the dwindling number of destroyers available in Home waters....and the huge demands made on them...the three "anti-invasion flotillas" were NOT the permanently-constituted flotillas that Fleming's early account of anti-invasion preparations would hint at. The Destroyers were "told off" to form anti-invasion flotillas in the event of invasion...but in the meantime they were busy fulfilling a whole range of OTHER duties around the UK and right out into the Atlantic! Some were retained for the patrol sweeps along the Continental coast....but other destroyers in the so-called "anti-invasion flotillas" were escorting the coastal convoys down the East Coast, and others were escorting departing and arriving convoys right out into the Western and Northern Approaches! They were never to steam more than a maximum of five days from their port of assignment in the event of invasion - but that means that in worst circumstances, if Sealion had been launched with minimal early warning - it could have been several days before the Royal Navy could have mustered its maximum number of anti-invasion destroyers ready to enter the Narrows!

 

Reading Friedrich Ruge (mentioned in a link), he considered Sealion under the conditions of late 1940 as hopeless.
Success would have been possible if shipyards, starting after the victory in Poland, built at least 100 Marinefährprahme
https://en.wikipedia.org/wiki/Marinef%C3%A4hrprahm
and attack as soon as possible after Dunkerque.

 

All very alarmist. Summing up some worst case scenario, while Germans get a blanket pass on all the risks they'd have had to undertake.

 

They operated in daylight during Dunkirk.

They'd do the same during an invasion.

 

They operated in daylight SOME of the time; operations at Dunkirk depended on the tide, and it permitting them to use whichever of the three routes to and from the port and beaches due to the sandbars etc....and daylight operations were several times postponed.

Dunkirk proved the Norway Rule; stuck travelling to and from Dunkirk in narrow corridors they had very little freedom to manouver to avoid the fall of ordnance - and if hit, they suffered horrendous manpower losses because "trimming" something as small and light as a destroyer meant getting evacuees as far belowdecks as possible. That's why A/ it looks as of some of the shiploads were quite small in number, and B/ when vessels WERE hit and sunk, losses were so high - evacuees down as near as possible to sea level or below would never make it out. Exactly the same thing happened when evacuating destroyers and cruisers were attacked off Crete in late May 1941. What Dunkirk demonstrated was how vital sea room and trimming meant for survival in a period when the Royal Navy was still somewhat behind the game in providing adequate gun AA defence.

As for doing the same in an invasion....no; the RN need to maintain a high "sortie rate" out of its designated destroyer flotilla ports in the event of an invasion - because they would need to re-arm very frequently if they attempted to operate by day. As again at Crete, the real destroyer killer is ordering them to operate in an environment where the enemy enjoys air superiority, and is free to attack you at will and repeatedly....some destroyers standing off Norway experienced two dozen air attacks a day!...and standing off every attack is a steady and high rate of depletion to your AA munitions Destroyers sortie'ing from Portsmouth/Plymouth or the Medway would barely make it into the invasion area by daylight before they'd have to return again or head for the nearest RN depot to re-arm.

Sortie'ing by day means experiencing repeated air attack, leading to rapid depletion of munitions - and not much point getting into the invasion area and unable to do anything, is there? It would ALSO mean that, despite the very best efforts of captains and crews, the destroyer flotillas would experience a gradual depletion of numbers. Operating at night at least means the removal of the Luftwaffe as a factor...especially if the Navy wants to keep on attacking the invasion shipping lanes "day after day" with its best possible strength.

 

Just blame the Kriegsmarine....

4th November 1940

"Unpleasant discussion at the Reich chancellery: present were Göring, V Brauchitsch,Keitel. For the first time Führer doubted Luftwaffe successes and statistics of enemy losses on the basis of British and other press reports. For the first time,too, Jodl supported Göring and said he believes that the British are putting up their last fighters flown by trainee pilots and base commanders since they have nobody else left. Führer was visibly depressed. Impression is that at the moment he does not know how it will turn out. At the most inopportune moment possible the C-in-C started talking about the postponed "Sealion", and attacked the Navy and Luftwaffe. Göring flew into a rage, nearly got personal, and accused the Army of wavering in indecision at Dunkirk. Nobody mentioned the real reason.Even Keitel had to leave the C-in-C in the lurch, since he did not understand the discussion.In the end everybody agreed to blame the Navy because they had admitted not being equipped properly to defend the landing beaches wanted by the Army. Nobody from the Navy was there."

From " At the heart of the Reich" by Major Gerhard Engel

---------

[SIZE=12pt]Welll, somebody for sure was doing a lot for operation Sealion on the German side:[/SIZE]

[SIZE=small]http://www.devon.gov.uk/localstudies/100343/1.html[/SIZE]

 

It hardly matters the number of destroyers retained, if the UK is successfully invaded.

If it was worthwhile to risk the destroyers to fetch the remnants of the BEF (and no one expected the numbers of men saved, nor the light losses of the destroyers; merely 9 in total, 6 British and 3 French), then it was bloody worthwhile to do so to make sure the invasion failed.

The LW failed to defeat the RAF, and it needed to defeat both the RAF and the RN. In other words Sea Lion never even came close.

 

phylo_roadking,

With all due respect, it wasn't going to happen.

First you bring up the weather question:

Germany could shift things around between embarkation ports, but not launch an invasion in bad weather. The US and Britain couldn't do it four years later, high seas would swamp and sink landing barges, break up cohesion, and generally wreak havoc on any invasion force crossing the channel. Heavy cloud cover would hamper not just allied air response, but to an even greater degree German ability to support the landings.

The US in August 1941 had issues landing a single division at Guadalcanal. This despite a well developed and practiced amphibious doctrine, amphibiously trained troops, naval ships and personnel trained in carry out amphibious landings, specialized amphibious vessels and landing boats.

Britain studied the problem of amphibious operations at Staff Colleges in Britain and the Indian Army Staff College at Quetta all through the 20's and 30's and despite post war austerity developed the MLC (motor landing craft). They had three of these by 1930 to use in studying and developing tactics, proceedures and doctrine. In 1936 the Royal Naval Staff College at Greenwich, got into the fray and produced a recommendation submitted to the Chiefs of staff for creating a joint amphibious training command and using Royal Marines as a permanent force to be trained in, develop, test and in turn train other personnel in amphibious operations. By 1939 they had worked out many of the issues and problems unique to amphibious warfare and had a codified doctrine. Also in 1939 Britain had finished developing and started producing Assault Landing Craft and LSI/LSC's to transport invasion forces and had even carried out divisional sized exercises.

The United States Marine Corps prior to WWI had studied the problem and had established an organization called the "Advanced Base Force" (later to become the FMF). This force was designed to seize defended locations by amphibious assault. The Advance Base Force was maintained but not used during WWI, as Marine Corps and Navy attention was focussed on the fighting in Europe. The Allied defeat at Gallipoli in 1915 made most military thinkers come to the conclusion that an opposed amphibious assault was unfeasable. Post WWI cutbacks to the US military resulted in the US Army attempting to have the Marine Corps abolished as a redundant, second land army. The Navy still had the requirement for the seizure of advanced bases to support the fleet in the event of war in the Pacific, so as a matter of survival the Marine Corps fully embraced the amphibious mission. Because now the majority of military thinking was that amphibious operations against defended targets was not practical, the Navy and Marine Corps had to study the reasons behind the defeat at Gallipoli, the problems inherent in all amphibious operations and develop doctrines, organization, proceedures, tactics and equipment to allow them to overcome these factors. Much of the basic theory and doctrine was published in 1921 as "Operation Plan 712, “Advanced Base Force Operations in Micronesia". In line with this improved doctrine, the Advanced Base Force was redesignated, Marine Corps Expeditionary Force, also in 1921. In 1925 the Marine Corps stood up a seperate west coast expeditionary force, trained and organized to employ the developing amphibious doctrine. In 1921 the Marine Corps also conducted the first of it's post war amphibious exercises, the intial one involved in the landing of 4,000 troops. The 1922 exercise exposed problems with landing artillery in rough seas, proceedures and new landing craft were researched. During the winter 1924 exercises (two) in a simulated attack on US Army defensive positions in Panama and the seizure and establishment of an advanced base in Culebra. The attackers managed to overwhelm the defenders at Ft.'s Randolph and Coco Solo, but the exercise also exposed weaknesses, to include loading and unloading deficiencies, insufficient naval gunfire support, poor night landing techniques, and inadequate landing craft. 1925 exercises in Hawaii had 1,700 Marines simulating two divisions and were to invade Hawaii against 16,000 regular army and national guard soldiers. Two landings were made the primary was a success and broke the defenses, the secondary a designed diversionary effort was repulsed. The need for improved landing craft was the primary lesson learned. The senior observer stated: “The essential thing being to get men and material of the expedition on the beach in shortest possible time with least confusion, and in the best condition for immediate action, it is vital that every effort should be made to provide beforehand suitable means for transporting men and material from ship to shore." I do not think German preparations for Sea Lion adequately provide for this aspect.
The 1925 exercises led to the addition to the curriculum of the Company and Field Officers Schools the subject of ship to shore movement based upon lessons thus far learned. This segment when first introduced included just five hours of instruction, by the end of 1926 it had expanded to 49 hours. Increased manpower requirements in China and the wars they were fighting in Central America caused the landing exercises to be cancelled until 1930, the instruction in the schools was however expanded three fold.
By 1930's they'd developed the joint Navy/Marine Corps FMF, (Fleet Marine Force (1933)) they practiced, developed, studied and refined the necessary tactics, equipment and proceedures which were published in the Tentative Landing Operations Manual in 1934. It was immediately adopted and implemented with regards to; "the organization, theory and practice of landing operations by establishing new troop organization and the development of amphibious landing crafts and tractors." Improved Landing Craft were being researched, developed and prototypes tested and modified. Major amphibious training exercises commenced in 1935 to include the annual 'Fleet Landing Exercises' (FLEX). Updates to the original manual took place in 1935. In 1937 the "Landing Operations Doctrine, U.S. Navy 1937" was published and a revised edition in 1938. In 1935 the US Army started sending observers to the annual FLEX exercise. Prototype 50' ramped motorized landing launches were tested for landing light vehicles and artillery. While they worked, they were found not sufficiently stable for conditions other than a mild sea state. In addition to the two Marine Expeditionary Forces the Army sent a US Army Brigade for the 1937 FLEX exercise and another brigade for the 1938 one. One of the primary problems identified was that despite dedicated, trained landing craft personnel, more stable and manueverable landing craft needed to be developed. The last two pre-war FLEX exercises took place from mid-January to mid-March in 1939 and again in 1940. The testing of experimental landing craft during the Flex exercises led to the recognition by the Navy of the superior capabilities of the 36-foot Higgins “Eureka” boat in 1939. (The boat had been undergoing experimental testing by the Navy and Marine Corps in 1938). In September 1939, Donald Roebling was contacted and convinced to redesign his amphibian for adoption by the Navy and Marine Corps, it was approved in January and money approved in March 1940. The Navy had built several types of tank and artillery lighters (these were called W-boats and there were WL and WM types), in 1938 due to the increasing weight of light tanks the two types were consolidated into a ramped, 50' boat. A new improved 45' type was ordered from Norfolk Navy yards in 1939. Exercises continued, amphibiously trained units were expanded, landing craft improved, continuously up through the 7 August 1942 landing date for Guadalcanal.-and despite all this there were hiccups, but Germany was going to execute a larger more complex operation without all the background development and training and make it work?
The US Army did try a divisional sized landing exercise in January 1940, despite not having participated in the exercises since 1938. They attempted to land the 9,000 man 3d Infantry Division. Lack of amphibious training, inadequately trained boat crews, lack of experience in amphibious operation planning, etc. led to near disaster. The Navy had to halt the exercise over safety concerns, only 1,500 men were eventually landed, without logistical support, the rest of the men and material having to be unloaded across the Monterey Wharf. There was much finger pointing, but it did lead to the establishment of east coast and west coast amphibious training schools where the Marines passed on thier expertise to the 1st, 3d and 9th Infantry Divisions.

Germany spent the same between the wars period perfecting it's "Blitzkreig" brand of warfare. They developed the theory, tactics, doctrine, command, organization, weapons, equipment and trained at it. That's why they were successful in it's implementation during the early days of the war. The US and Britain had not spent the necessary time in developing this capacity. Do you think they could just throw together an ad-hoc force, with jury rigged equipment, and no training, no experience in the operational requirements of that type warfare and wage it successfully? No. So why should anyone assume the Germans could just throw together a force, with makeshift equipment, no specialized training, and successfully implement an operation that is universally considered the most complicated type military operation. The 1st Marine Division with all their advantages had to watch as their ships sailed away on August 9th, with half their supplies, most of their heavy weapons, a quarter of their troops. They had been landing/unloading for three days (7th, 8th, 9th). How would Germany put it's troops and supplies ashore quicker? And the Germans were looking at landing multiple divisions, not a single division. The Marines supporting fleet pulled out because an enemy cruiser force sailed in from Rabaul, 650 miles away, and wiped out the covering force for the invasion. This was late on the second night into the early morning of the third day. Do you really believe that the British couldn't have reacted as quickly, and probably much quicker to a landing? And unlike the US landing, the Germans would not have a stong covering force, cruisers and light cruisers would be almost overkill. Destroyers and MTB's would have a field day with the German shipping. Hell a frigate would be like a battleship in comparison to a machine gun equipped barge.

The whole thing was a pipe dream.

 

It's not really accurate to speak of "winning the Battle of Britain" or "defeating the RAF" as if, on a given day, that battle would be over and the RAF would be out of the picture. All the Germans could do was to keep the RAF, or more accurately 11 Group of Fighter Command, suppressed for as long as they devoted almost their entire strength to the task. As soon as the pressure let up, Fighter Command would bounce back as it did historically when the Luftwaffe turned to attacking London. Every German sortie in support of the invasion or against the Royal Navy would be one less on airfields.

The Luftwaffe would have some advantages in a invasion scenario. They'd be fighting over the Channel or the beaches, much closer to their own bases. The British would have less time to organize interceptions. The initial German landings would take out the Chain Home stations immediately covering the beaches and approaches, although adjacent stations could provide some coverage. Presumably the Germans would still direct a proportion of their attacks against airfields, but RAF controllers wouldn't know if an incoming strike was continuing inland or just going to hit a target on the coast and turn for home. And there would be British bombers in the mix, trying to hit German troops, shipping, or the invasion ports. Fighters and their commanders on both sides would have to balance the need to protect their own bombers and counter the enemy's. The two sides would be in roughly comparable positions, which might be more to the Germans' favor than the historical situation.

 

Phylo, I'm going to guess there were many radios in France reporting to GB (I know this was early before an organized network was formed), along with other comms going through Spain. I think it highly unlikely that the Germans were going surprise anyone with their invasion. Under the circumstances, I think Churchill would have sacrificed every vessel smaller than a cruiser to hit the channel. Even the little Motor Torpedo Boats could have created major disruption to such an operation. They had something like 40 knots and were armed with everything from .50 caliber machine guns, 20mm Oerlikons and 2 pound "pom pom" guns, along with their torpedoes. Imagine a couple of flotillas of those running at high speed down lines of towed barges at night.

If Naval-history.net is accurate, in 1940 there were four destroyer flotillas, four submarine flotillas, and a collection of Dutch and Norwegian naval vessels in home waters. This doesn't count the heavy vessels and their escorts which probably couldn't have gotten in and out before daylight, though with all the extra AA support maybe they would have went in also.

The main reason I think it would have been so disastrous for the Germans is because we're talking about such a small area. It isn't like the battles in the Pacific involving hundreds of thousands of square miles to watch, and long distances to move forces. Everything could have been poised close enough to the channel to intervene.

It's different than D-Day also, because the allies had complete control of both the land and the sea. Even if the Luftwaffe had knocked out the RAF, they were never going to challenge the RN in a concentrated area like that. The navy wouldn't have even had to challenge any of the German fighting ships, just shoot up the motley collection of towing and towed vessels. Anything still on the water the following morning would be easy meat for the submarines. Any vessels that did get through would never get back to bring in a second wave because of those same submarines.

As for German naval forces in a night fight with fast vessels that are deliberately avoiding the fighting ships, I don't think they could have done much except further confuse the situation.

I think the BoB was a tremendous boost for British morale when they needed it. And that fight swayed American opinion towards war well before Pearl Harbor. I just don't think Great Britain was ever in real danger from a sea-borne invasion.

 

As someone mentioned earlier, even the British Admiralty acknowledged that the Germans could probably pull off an initial landing; they key issue would be the flow of reinforcements and supplies thereafter.

 

Kodiakbear...

Actually - one of THE major problems the British had was the relative opacity of what was happening on the other side of the Channel. There were virtually NO intelligence sources in the areas they needed at the time. See Fleming on this. They were in the same position as the Germans....they had no idea of exactly what was happening in the Continental littoral right then.

Yes they might have received word via diplomatic channels down via Spain through to Portugal or via the Embassy in madrid - virtually in a permanent state of siege with all movements of all British diplomats and attaches followed (it made it frightfully difficult over the years to pick up evaders etc. that made it over the Pyrenees)- but the vital thing is that they're not ever going receive word within hours that way...which is what they actually needed, not word a day or three late.

We actually had very few MTBs, coastal forces were in the early stages of development....and what MTBs we had were relatively lightly armed in 1940. The heart of the coastal forces was actually still the RN's MLs and a scattering of early MGBs. And the coastal forces were likewise NOT clustered in the real Sealion invasion areas, they were assigned to flag commands the length of the East and South Coasts.

In "home waters", yes - but "home waters" includes Rosyth, the Humber, Scapa Flow etc., etc....

Which is why the three specifically-formated "anti-invasion flotillas along the South Coast and at the Medway.....to be able to rapidly react to German movements.

.

That's the thing - we DID have hundreds of miles of coast to watch and protect. Even once the details of Sealion were intercepted, it only "narrowed down" (!!!) to Deal round to Brighton! BEFORE that it included all of the East Coast....

Hence issues such as the 2nd NZ, providing the main infantry elements of MILFORCE, being billeted as far back from the coast as Maidstone; they had roders to deploy south past Ashford and on to Hythe/Folkestone.....or through Ham in the general direction of Rye.....or to deploy EAST to behind Deal! On the day it would have meant a roughly forty mile forward deployment in reaction to any word of German landings...!

...apart that is from the fact they'd done it off Norway, they'd done it at Dunkirk, and they were going to do it again a year later at Crete?

Hold up on the discussion of submarines....

The Channel Narrows are actually very shallow for most of their breadth; in WWI and again in WWII, several uboats came to grief on the sandbars of the Narrows. Uboats transiting the Channel in WWI into the Western Approaches did it on the surface....

And the two (2) times that the KM attempted to transit the Channel after the Occupation of France, one of those did indeed come to grief on the Narrows' sandbars.

Unfortunately - the factors impinging on German Uboats also affect the RN's submarines in the Channel Narrows Coastal waters that are too shallow for uboats to operate in are too shallow for RN submarines too...

 

Nor would Sealion ever have been launched in bad weather....just as it was never launched ostensibly because of the failure to obtain even local air superiority. The weather protected the British Isles every bit as much as the RAF did....there were only three protracted periods during September 1940 that would have been suitable for invasion, and the famous "Cromwell scare" was one of them...but the weather doesn't get thanked often enough

In regards to the rest of your post regarding other nations' development of the doctrine of ampibious warfare, and developing the technology and the tactics required while Germany didn't....you're forgetting one thing...

Germany had already done - successfully - what they planned to do for Sealion; they had put together a ragtag ampibious force that got ashore in captured ports and harbours, and rapidly deployed to take over half a country in less than four weeks, despite the efforts of the locals AND the British and French attempts to stop them. They had sent their forces off hidden on board merchant vessels, and supported by a rolling "sea bridge" of fishingboats and coasters...to Norway Which was a significant lesson for German planners - that shoestring, impractical improvisations worked...

 

First of all - some of the affected airfields were pretty badly hit. Biggin Hill for example was "open" but repeated raids had rendered it impractical for use, and all its squadrons had been posted elsewhere. In many cases the damage done was quite serious....but as long as aircraft could actually land they were regarded as being useable...!

The Luftwaffe actually regarded themselves as running out of airfield targets by the start of September! IIRC there's a planning meeting mentioned in E.R. Hooton where the lack of targets that were valuable enough to bring up British fighters to defend them meant that the Luftwaffe was going to have to find more targets - which was why noone actually objected to turning on London! The British had suddenly got better as husbanding their resources, putting up one or two flights against vastly superior numbers, to disrupt a raid as mnuch as bring down bombers....while the Luftwaffe didn't JUST want to hit RAF support and infrastructure targets; even though "free hunting" by LW fighters had been stopped in favour of close support for the bombers, they still saw bringing RAF fighters up to be knocked down as a vital part of the air superiority battle - and the British had stopped playing!

But massive air attacks on London would mean that the RAF would HAVE to react with massive numbers of fighters - which of course it did, leading to the huge air battles over the captial

So it wasn't a case of simply Fighter Command flying back into fields it had previously vacated....if the Luftwaffe was active against the RN. It wouldn't have taken much at all to keep the Eleven Group fields continually supressed - and was in fact one of the responsibilites the Luftwaffe planned for, along with continued attacks on coastal defences, AND attacks on the RN. And in fact they did successfully continue the airfield interdiction raids during the periosd of massive daylight raids on London *


As for the issue of early warning...

It's worth remembering that NO Fighter Command tracking of incoming raids was done by radar after enemy aircraft passed the coast. ALL reporting of aircraft movements over land and and subsequent was done by RAF listening posts...and of course by the Royal Observer Corps. So really it was the other way round - destruction of the Chain Home stations would have blinded the RAF to ANY enemy aircraft movements out beyond the coast of England until they crossed the coastline and entered airspace monitored by ground stations Thus the RAF would have had just as much information on incoming raids as they did during the BoB apart from the long range RDF returns warning of the buildup of enemy aircraft over France, and tracking them incoming TO the UK.

What however would gradually....or maybe rapidly, who knows? ...degrade the RAF's ability to monitor Luftwaffe movements over the South of England was - one by one, Royal Observer Corps monitoring posts disappearing off the telephone network as German land forces rolled over the landscape!

Regarding this...

It would have been an even worse situation that you might think....

Not only would there be RAF bombers attempting to attack the invasion beaches....beached troops, supplies etc. were regarded as one of the few practical targets for the medium bomber force...and hit the acdebouchment points from the beaches themselves, the roads and breaks in the landscape where the Heer would be trying to get off the beaches....AND Blenheims assigned to Army tasking would be attempting to privide Close Air Support to British troops on the ground,along with any surviving Fairey Battles....AND RAF fighters attemting to protect both AND combat any Luftwaffe fighters in the invasion area...

The area was going to be flooded with literally hundreds of bombed-up RAF and Fleet Air Arm trainers under Op BANQUET! All of them flying into the invasion area carrying gas or light ordnance...and without the benefit of radio IFF transponders!!! On the day it would indeed have been a hell of a furball up there...

And frankly, the Luftwaffe....not yet tied to a GCI doctine for controlling its fighters...would have more of an advantage - more of a lead in thinking "on their feet" so to speak - than Fighter Command. Just as the Heer spent more time and emphasis on training for independent thought and lower-level decisionmaking in the heat of battle than the British Army did, the Luftwaffe was still not "hampered" by ground controllers vectoring them onto targets. They had greater flexibility of action than Fighter Command pilots...and that might have stood them better in such a furball



* In fact - IF Eleven Group had had to be withdrawn north of the Thames, ceding local air superiority to the Luftwaffe and allowing Sealion to be launched...

Far from Dowding simply being able to shift squadrons back to them while the Luftwaffe were busy elsewhere....re-opening those airfields would simply have added another huge air defence responsibility to his list in a time of greatly-straitened resources...! He'd have had to set aside x-number of fighters for THEIR protection, weakening an already-weakened Fighter Command even further and reducing the number of fighters available for all his other responsibilities in the event of invasion!

 

Very informative thread. I'm learning a lot.