Sealion compared to historical amphib assaults?

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Tsofian
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Re: Sealion compared to historical amphib assaults?

Post by Tsofian » 27 Apr 2018 00:21

sitalkes wrote: The batteries in open positions and open casemates would have been vulnerable to dive-bomber attacks. There weren't any dive bombers on the Allied side in Normandy in 1944, when the Germans often (but not always) had properly designed, fully enclosed reinforced concrete bunkers designed to resist heavy calibre naval guns. Those positioned to fire across the beach didn't even have embrasures facing the sea and could not be silenced until somebody with explosives or a tank got close enough. In 1940 the coastal emplacements (even the ones in forts) were in open positions or rectangular ones made out of bricks with open fronts.
There are a total of 294 serviceable JU-87 aircraft in the inventory in units facing England.

The Norwegian Batteries were in open positions and none were knocked out be German dive bomber. Japanese positions in the Pacific were hit by dive bombers, but often were not put out of action. The Japanese attack on Midway with over 100 aircraft did not put many of the batteries out of action

The British batteries were generally heavily camouflaged. There were also dummy sites. The Germans flew very little photo recon over the beaches (compared with over 3,000 sorties over the D-Day beaches) and had absolutely no humint in the UK. This will make the job of the dive bombers much harder. Plus the use of smoke by both sides will make these batteries even more difficult to attack.

Also the German Dive Bombers are supposed to keep the Royal Navy at bay, hit British air fields, interdict British counter attack, suppress British artillery and attack British railways and road systems. One of their critical missions is supporting the paratroopers. Even if the 300 odd Stukas are flying 2 sorties a day they can't meet all these obligations. Also, how long can they maintain this operational tempo? What sorts of losses will they suffer? If there are any fighters around the Stukas will get thrashed, as they did historically.

The Stukas are the most effective aircraft the Germans have against surface ships. They are the best support for the paratroopers. They are the only aircraft that have a good chance of silencing the coastal batteries. They would be the most effective at attacking armored units and artillery. But there aren't enough of them to perform all these missions. So what would the choices be? Remember that the German air force has to defend both flanks of the invasion area all day long. Stukas have a range of 300 miles with a 500 kg bomb load. Dunkirk to Brighton is over 100 air miles. This means almost no loiter time over the western edge of the battle area. Assuming 8 hours of coverage is required and 25 aircraft in a group that means 200 sorties just for that mission alone.
This has long been one of the biggest problems I see with Sealion. The Luftwaffe doesn't have enough aircraft to meet all the missions they need to perform to support the Invasion.

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Re: Sealion compared to historical amphib assaults?

Post by sitalkes » 27 Apr 2018 04:48

There are two incorrect assumptions here:

1. everything has to be done on the same day or even at the same minute. No it doesn't, the batteries can be bombed before the invasion, for instance. That this didn't happen is why the invasion would have failed - the Luftwaffe didn't follow its orders and support the invasion plan and didn't even have a plan for supporting the invasion until September 28, long after it had been effectively cancelled.

2. the JU 87 wasn't the only dive bomber in the Luftwaffe. The best was the Ju 88 and almost all German bombers had a dive bomber capability.

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Re: Sealion compared to historical amphib assaults?

Post by sitalkes » 27 Apr 2018 07:14

Tsofian wrote: The British batteries were generally heavily camouflaged. There were also dummy sites. The Germans flew very little photo recon over the beaches (compared with over 3,000 sorties over the D-Day beaches) and had absolutely no humint in the UK. This will make the job of the dive bombers much harder. Plus the use of smoke by both sides will make these batteries even more difficult to attack.
and yet...
Beach B fortifications map.jpg
Martin Marix Evans says the German maps were pretty accurate, and they are accurate enough to be used by the archaeologists searching for the fortification sites.
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Re: Sealion compared to historical amphib assaults?

Post by Knouterer » 27 Apr 2018 19:13

Marix Evans may have thought the German maps were "pretty accurate" but that assessment doesn't seem to be based on anything much. He didn't really take the trouble to find out what was actually waiting for the Germans, judging from his book.
On Beach B, the batteries were disposed like this (Schenk's sketch map with my additions, the blue bits are the advance detachments):
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Re: Sealion compared to historical amphib assaults?

Post by Knouterer » 27 Apr 2018 19:18

None of these batteries had been pinpointed by the Germans apparently. From the air, the Greatstone battery looked like this, with the gunhouses camouflaged as innocuous beachfront cottages. Note the concrete tank barriers:
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Re: Sealion compared to historical amphib assaults?

Post by Knouterer » 27 Apr 2018 19:23

This shot from Google Earth, from 1944-45, shows the battery at Hythe in front and to the right of the Hotel Imperial, I believe. There seem to be three gun houses, but there were only two guns in 1940. The third may be a later addition, or perhaps just a decoy. Today, there is a small parking lot there and no trace of any buildings remains.
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Re: Sealion compared to historical amphib assaults?

Post by Knouterer » 27 Apr 2018 20:42

Of course, it all depends on which date you want to pick for the invasion. With regard to the 400 series of batteries: according to Ian Lofting, author of a recent book on the British preparations to resist invasion (We Shall Fight Them), and present on this forum, on 30 Aug the Chiefs of Staff decided that coast defence artillery needed to be strengthened between North Foreland and Dungeness, with Eastern Command being informed of this on 3 Sept. On 26 Sept 412 Bty reported being in action by day (limited operational, probably without searchlights). On the following day 415 Bty declared the same and on 30 Sept so did 416 Bty (Jury's Gut, on the other side of Dungeness). Source: WO 166/11, GHQ Coast Defence file.
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Re: Sealion compared to historical amphib assaults?

Post by Bergedorf » 28 Apr 2018 02:18

There are two incorrect assumptions here:

1. everything has to be done on the same day or even at the same minute. No it doesn't, the batteries can be bombed before the invasion, for instance. That this didn't happen is why the invasion would have failed - the Luftwaffe didn't follow its orders and support the invasion plan and didn't even have a plan for supporting the invasion until September 28, long after it had been effectively cancelled.

2. the JU 87 wasn't the only dive bomber in the Luftwaffe. The best was the Ju 88 and almost all German bombers had a dive bomber capability.
1. Dive bombing could not have be done before daybreak, so it had to be done before S-Day. If you look on the meagre material results (moral results are another matter) of dive bombing at Sedan, there is no much hope that divebombing could have achieved much in favor to the possible costs.

2. Only some pilots had the qualification to go in a steep dive with a Ju 88. The most common attack with a Ju 88 was a shallow dive (You can read about it in Boog, Horst: Die deutsche Luftwaffenführung 1935–1945. Führungsprobleme. Spitzengliederung. Generalstabsausbildung. Deutsche Verlags-Anstalt, Stuttgart 1982, or Stahl, P.W.: Kampfflieger zwischen Eismeehr und Sahara). You would see neither He 111 nor Do 17 doing dive bombing.

So results would probably be:
-high losses on Ju 87
- minor damage on emergency batteries and coast defences
- an indication that invasion is emminent, with reactions on the british side.

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Re: Sealion compared to historical amphib assaults?

Post by Knouterer » 28 Apr 2018 07:36

This discussion rather belongs in the thread about Luftwaffe & RAF preparations for Seelöwe, but on the subject of intelligence, I was just writing a few paragraphs about that, so I'll just quote myself:

German intelligence about the British defences was, in a word, poor. General Günther Blumentritt, who was chief of the operations staff of Von Rundstedt’s Army Group A, wrote after the war (1949) in an article for the Irish Defence Review (An Cosantoir): "Intelligence from England was extremely meagre. No one knew whether there were any coastal defences or field fortifications on the English coast or where they were, if they existed. It was not known which beaches were mined. No one could say exactly what forces the British had available for defence."

By August the Luftwaffe had found that the cost in men and machines of low-level reconnaissance over Britain was too high – about two dozen reconnaissance aircraft, mostly Dornier Do 17P, had been shot down – and had switched to high altitude flights, using among other types Ju 86P aircraft with special supercharged engines and pressurised cabins, which could not be intercepted at that time. However, at the altitudes at which these planes flew, typically over 30,000 feet (9,000 m), their cameras could not catch much detail. In addition, photo interpreters were not very well trained or equipped. The Coastal Command airfield at Thorney Island and the naval air stations at Ford and Gosport were attacked early on in the Battle of Britain because German intelligence had wrongly identified them as fighter bases.

While German intelligence services were more or less correct in their estimate of the overall strength of the British ground forces and the number of divisions, they knew little detail. The Befestigungskarten or “fortification maps” drawn up on the basis of aerial reconnaissance did show a fair number of pillboxes and barbed wire barriers, and also searchlights and AA artillery positions (obviously), but not, with a very few exceptions, the “emergency batteries” installed on the coast since May, or the artillery positions further inland. The three-gun battery installed by the Royal Marines at Dungeness Point had been spotted – it would have been difficult to hide on that flat open stretch of shingle – but not the several cleverly camouflaged batteries along the gently curving coastline from Dungeness to Folkestone, which would be Beach B in the German plans. In a number of cases, photo interpreters believed they saw gun batteries where there were none, for example on Beachy Head or in Lade Fort (Dungeness No. 2 battery) two miles north of Dungeness, for which they noted “a battery of four guns with armour protection”. No guns had been installed there for half a century at least. The army produced a “military-geographical assessment” (Militärgeographische Angaben), apparently without consultation with the Luftwaffe, which was published in several thousand copies in August. This work was apparently based on a hurried search through libraries and newspaper archives in Berlin, and contained much erroneous and irrelevant information, including maps and photos showing buildings, bridges and other landmarks which had disappeared decades ago.

This lack of detailed intelligence did not worry the army planners unduly. In the German military philosophy, the enemy’s resources and plans did not weigh very heavily in the balance. What counted was confidence, based on sound preparation, and the will to win. As general staff officers liked to remind each other, der Geist bewegt die Masse. The spirit moves the mass. Consequently, intelligence officers at all levels had a relatively low status and their input was not much sought after when plans were drawn up. The operations officers (Ia) often wrote their appraisal of the enemy without reference to their colleagues.

It's possible, by the way, that Blumentritt's negative comments were influenced by the fact that his boss, von Rundstedt, didn't want to have anything to do with Seelöwe and reportedly called the whole idea nonsense (Unfug). Planning for the invasion was therefore carried out at the next lower level, 9th and 16th Armies.
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Re: Sealion compared to historical amphib assaults?

Post by Knouterer » 28 Apr 2018 09:05

Knouterer wrote: In a number of cases, photo interpreters believed they saw gun batteries where there were none, for example on Beachy Head or in Lade Fort (Dungeness No. 2 battery) two miles north of Dungeness, for which they noted “a battery of four guns with armour protection”. No guns had been installed there for half a century at least.
Picture of Lade Fort (1960, today it's completely surrounded by houses). It's likely it would have been dive-bombed on S-Day, and so would Dymchchurch (Grand) Redoubt, where there were no guns either, just a platoon (or two) of a stevedore battalion.
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Re: Sealion compared to historical amphib assaults?

Post by Tsofian » 28 Apr 2018 19:12

sitalkes wrote:There are two incorrect assumptions here:

1. everything has to be done on the same day or even at the same minute. No it doesn't, the batteries can be bombed before the invasion, for instance.
Actually a large number of these missions MUST occur at the same time. According to Luftwaffe doctrine on S-Day the dive bombers will have to perform the following missions: Interdict the Royal Navy, attack any coastal batteries and provide close support to the beaches, provide direct support to the air landings, attack any British armored units and provide suppression against artillery units. All German bombers were designed to perform dive bombing, but in 1940 the Stuka units were the ones dedicated to these missions.

300 aircraft aren't enough to provide all these missions in a single day, let alone for several days with a high operational tempo. If the German's can't make an airfield in England operational very quickly they are going to wear out their Stuka units.

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Re: Sealion compared to historical amphib assaults?

Post by Knouterer » 29 Apr 2018 08:36

Knouterer wrote:An interesting comparison could be made between Omaha Beach and landing zone B (between Folkestone and Dungeness) in the German Sealion plans.
Obviously there are very significant differences but there are interesting similarities too. Both involved a landing on a frontage of similar width by two infantry divisions, supported by a similar number of tanks (DD tanks in 1944 vs submersible/swimming tanks in 1940). Both beaches followed a gentle curve giving the defenders a good field of fire.

Most people would assume that Omaha beach was much more strongly defended, which may be true in terms of concrete, mines and other obstacles, but I do think the British defences by the end of September 1940 (the earliest possible date for an invasion) were stronger in terms of men and firepower per km. Of course, a direct comparison is difficult because the defences were organized and equipped very differently. The Britsh had about ten coastal defence guns of 5.5in and 6in calibre pointing out to sea, the Germans had none. On the other hand, the Germans had more guns, including a couple of powerful 88 mm Pak guns, pointing along the beach itself, which the British had not. Concerning indirect artillery support, the British had more and bigger guns within range, including four 9.2in (234 mm) railway guns.
It seems a safe assumption that the Germans, even if they somehow managed to get across in good order and on schedule, would have suffered at least as many casualties on S-Day as the Americans did on D-Day.

One of these days I'll work it out more precisely.
I have just been reading a history of the Big Red One by James Scott Wheeler (p. 263-265):
The 16th and the 116th Infantry Regiments had suffered heavy losses during the assault; the 16th was placed in reserve the next day (and did not resume offensive operations until the end of the month, after having received 1,200 replacements). This was possible because the 1st and 29th Divisions were firmly established ashore by the end of 7 June and the 2nd Inf Div had begun to land.

For the Germans, no such respite would have been possible on S+1. Every man still standing would have been needed to advance, secure the planned perimeter about 15-20 km inland and defend it for a week or so before any reinforcements could be expected.
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Re: Sealion compared to historical amphib assaults?

Post by Tsofian » 29 Apr 2018 15:52

[quote="Knouterer"
I have just been reading a history of the Big Red One by James Scott Wheeler (p. 263-265):
The 16th and the 116th Infantry Regiments had suffered heavy losses during the assault; the 16th was placed in reserve the next day (and did not resume offensive operations until the end of the month, after having received 1,200 replacements). This was possible because the 1st and 29th Divisions were firmly established ashore by the end of 7 June and the 2nd Inf Div had begun to land.

For the Germans, no such respite would have been possible on S+1. Every man still standing would have been needed to advance, secure the planned perimeter about 15-20 km inland and defend it for a week or so before any reinforcements could be expected.[/quote]

Don't those replacements arrive on the same vessels that brought the initial wave? So the transport flee needs to survive the initial passage, several days off the beachheads the return voyage, reloading at the Occupied ports and then the second crossing back to England? Does the second wave require the same sea lift as the initial wave. I understand there was some replacement tonnage available, I think around 10%. Given the situation how much of the second wave could have crossed on time?

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Re: Sealion compared to historical amphib assaults?

Post by Tsofian » 29 Apr 2018 16:10

This probably belongs in a different thread but here goes.

If this continues to be a campaign of attrition for both air and naval units how long will the Luftwaffe survive as an effective fighting force? The British were able to win the Battle of Britain air campaign due to their ability to replace losses more effectively than the Germans, and to maintain a higher level of operational readiness. How would this have been different if the Invasion had gone in? The air battle over the beaches might have looked a lot like that of Dieppe. At Dieppe the Allies hoped to draw the Luftwaffe into a decisive battle. The Invasion of England would be similar. The RAF must engage with all its resources. Tactically the Luftwaffe was able to be very effective at Dieppe, inflicting double the losses on the Allies that they suffered. However the Luftwaffe could not afford the losses they suffered and it was a strategic victory for the Allies.

http://www.luftwaffe.cz/dieppe.html
"The ill-fated Allied landing at Dieppe on 19 August 1942 was intended as a reconnaisance in force to learn the techniques required to breach Hitler’s Atlantic Wall.The air operations in conjunction with Operation Jubilee resulted in some of the fiercest air battles of the war. The RAF saw the operation as an opportunity to force the Luftwaffe to do battle on their terms. To that effect, the RAF committed 49 fighter squadrons: four Spitfire IX, 42 Spitfire V, and three Typhoon. Additionally there were eight squadrons of Hurricane fighter-bombers, four squadrons of reconnaisance Mustangs and seven squadrons of Blenheim and Boston light bombers.

Opposing this force were the experienced Jagdgeschwader JG 2 and JG 26. Each were equipped with approximately 115 fighters. About 220 bomber aircraft were operating from bases in northern France and The Netherlands. The German fighters would, therefore, be outnumbered by about three to one.

The Allies fighter performance on the day was hailed as a great victory in stark contrast to the humiliating losses of the army and the not inconsiderable losses of the navy. The RAF’s victory claims amounted to 47 destroyed, 27 probable and 76 damaged Fw 190s, 3-1-2 Bf 109s, 33-8-46 Do 217s, 8-3-11 Ju 88s and 5-0-0 He 111s. The Allied losses amounted to 71 pilots and 10 aircrew killed or missing, and 106 aircraft, including 88 fighter aircraft.

Actual Luftwaffe losses, however, were actually considerably less at 48 aircraft. Twenty-three fighters were lost, 16 from JG 2 and seven from JG 26. Fourteen pilots were killed, eight from JG 2 and six from JG 26."

The forces will be much more equal. Even if the losses are simply proportional to Dieppe and the Germans suffer double the losses it is probable the Luftwaffe will become combat ineffective within a few days. Once the Luftwaffe is ineffective how will the Germans keep the Royal Navy out of the Channel? The KM surface forces are unlikely to survive as long as the Luftwaffe. The KM destroyers are powerful vessels but suffer terrible operational readiness due to their machinery, and require special fuel that is unavailable in France, except for supply from Germany by rail. Also how many torpedoes for the destroyers are available in the invasion ports? At some point the Germans will run out of platforms that can engage the three capital ships and their escorts that are ready to charge down the channel. The effect of Rodney, Nelson and Hood, as well as their cruisers and destroyers against the transport fleet and the beacheads, if those vessels are not effectively engaged is not difficult to imagine.

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Re: Sealion compared to historical amphib assaults?

Post by Gooner1 » 30 Apr 2018 17:01

MarkN wrote: I see FSRs as a written document but little, if any, practical evidence that that document had any meaningful effect on changing attitudes.
You see the FSRs as 'proof' that such a change had already occured. And...
If there was a change from a small war mentality it happened 20 years earlier. How many of the senior officers in the British Army at that time did not have direct experience of Big War?

So you either believe that the British Army did not have a big war mentality even whilst they were fighting and winning a big war, or that they abandoned the mentality that they would have to fight big sometime after the Great War.

FSR Vol II 1935.

Chapter X

Special Types of Warfare

93. General considerations

1. In the preceding chapters warfare in a highly developed country against a civilized enemy has been the type mainly considered. ...

MarkN wrote: And yet they did exist.
One less thing for you to moan about then :D
18 field divisions on the orbat is 'enough' to justify the existance of at least 6 corps level field commands and a pair of army level field commands. Perhaps even an army group (*****) level field command to sit at the very top.
Uh, huh. At the time of the Munich conferences the total number of divisions deployable to the Continent was two.
And with no political intention to send an expeditionary force of any size to the continent, forming corps and even army level field commands comes pretty close to gross insubordination.

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