Sealion compared to historical amphib assaults?

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Knouterer
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Re: Sealion compared to historical amphib assaults?

Post by Knouterer » 21 Apr 2018 22:04

For those who want to know exactly, this is where the Hastings battery (341 Battery) was according to local historians (black cross). The battery observation post and the searchlights were higher up on the cliff apparently.
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Re: Sealion compared to historical amphib assaults?

Post by Tsofian » 21 Apr 2018 23:36

Knouterer wrote:That's another major problem for the Germans - they were it seems almost completely unaware of the emergency batteries on the coastline. Here's a map from Schenk, with my additions, showing where the ships for Beach C would anchor. The crosses indicate where the batteries were (two 6-inch guns each). I did not indicate the Hastings battery because I didn't know where exactly it was at the time, but it was down on the beach below the cliffs, within easy range (3,000 m or so) of the "anchoring zone west for tow units".
Clearly, if just half of these guns were still in action by the time the transports dropped anchor, the latter would have a serious problem.
During World War I the British Batteries at Hartlepool fired 123 rounds at two battlecruisers and a large armored cruiser. Range opened was approximately 4,000 yards. The batteries were under counter bombardment by the German vessels. IIRC they scored 7 hits from those 123 rounds. This is 6% hits under some of the most difficult tactical situations. There is no reason to believe that the British guns in 1940 would have performed any less well and considerable reason to expect they would have performed better. The 5 inch guns at Wake scored at least 13 hits at ranges from 4500 yards and did not have full fire control (again firing while under bombardment, at high speed maneuvering targets).

I think historical precedent for between 10 and 20% hits. Batteries would have 100-200 rounds per gun for the new batteries, I can't recall what a prewar battery had in its magazines, but at least 200 rounds per gun would seem reasonable. This gives a battery between 10 and 40 hits against fully loaded transports.

Also to be noted is that in the case of Wake and Hartlepoole that counterfire from the opposing warships was unable to silence any of the guns, even though those weapons were in open emplacements with no overhead cover.

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Re: Sealion compared to historical amphib assaults?

Post by Knouterer » 22 Apr 2018 07:53

Tsofian wrote:
During World War I the British Batteries at Hartlepool fired 123 rounds at two battlecruisers and a large armored cruiser. Range opened was approximately 4,000 yards. The batteries were under counter bombardment by the German vessels. IIRC they scored 7 hits from those 123 rounds. This is 6% hits under some of the most difficult tactical situations. There is no reason to believe that the British guns in 1940 would have performed any less well and considerable reason to expect they would have performed better.
That is indeed an interesting episode in the context of Seelöwe. It is believed the gunners scored more than seven hits, but a number of shells glanced off the armoured sides of the battlecruisers without exploding. On the morning of 16 December 1914, three German battlecruisers, with a combined armament of 20x11” (28 cm) guns, 12x8” guns and 32x6”guns, bombarded Hartlepool, which was defended by three 6” Mk VII coastal guns (still standard equipment in 1940) manned by Territorials of the Durham Royal Garrison Artillery. Although the very first German shell severed the telephone communications between the command post and the guns, they managed to put up an effective resistance, scoring a number of hits and killing about 80 German sailors and wounding 200. The three German ships fired 1,150 shells in all in 42 minutes, mostly at the town, but failed to disable any of the guns, and the gunners suffered only two casualties, both outside the batteries. They did however experience various technical problems and a lighthouse partially blocked their view of the ships, bringing their rate of fire down to one round per minute per gun during the engagement, instead of the 6 rpm an experienced crew could achieve.

Closer to the Seelöwe time frame, during the invasion of Norway, while some Norwegian coast batteries did not fire at all, or ineffectually, others caused serious destruction.
At Oslo, the heavy cruiser BLÜCHER was heavily damaged and set on fire by two hits from 28 cm guns of the Oscarsborg fortress (plus several hits from a 15 cm battery nearby), and then finished off by land-based torpedoes. Some 350-400 German sailors and soldiers lost their lives.
In the continuing action, the Norwegian batteries scored seven more hits on the LÜTZOW and the BRUMMER (which were next in line), and seriously damaged the latter (later sunk). The Germans were forced to put their main landing force ashore south of Oscarsborg, some 20 miles from Oslo city, and make their approach by land (they arrived in the capital late that night).
During the day (on April 9) the Oscarsborg positions were hit with some 500 aircraft bombs (50 and 250kg), plus about 100 shells from the LÜTZOW, without a single gun being disabled. The island forts only surrendered the next day, after Oslo fell.
At Bergen, the cruiser KÖNIGSBERG was seriously damaged by 21 cm guns, and sunk the next day by Sea Skuas of the Fleet Air Arm.
The fortifications at Kristiansand (fortress Odderöy, 21 cm and 15 cm guns) also put up a resolute fight, twice repulsing the landing force led by the cruiser KARLSRUHE.

Other examples that might be quoted are the French CBs at Dakar which in Sept. 1940 caused the British and Free French to abandon the landing attempt (BARHAM was hit twice).

It all goes to show that admiral Fisher was right when he said "no sailor but a fool attacks a fortress".
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Re: Sealion compared to historical amphib assaults?

Post by Tsofian » 22 Apr 2018 23:41

Knouterer wrote:
It all goes to show that admiral Fisher was right when he said "no sailor but a fool attacks a fortress".
That was why I named the game I wrote for the Admiralty Trilogy "No Sailor but a Fool!"

It has a Seelowe scenario and one with the cross Channel guns as well

Just thought I would throw that out

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Re: Sealion compared to historical amphib assaults?

Post by Knouterer » 23 Apr 2018 07:18

Noted :milwink:

Another interesting episode is the Dardanelles operation, where in February-March 1915 British and French battleships tried to force a passage, but in spite of their vastly superior firepower were repeatedly beaten back by the (mostly obsolete) Turkish guns on shore.
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Re: Sealion compared to historical amphib assaults?

Post by Kingfish » 24 Apr 2018 11:06

Knouterer wrote:Closer to the Seelöwe time frame, during the invasion of Norway, while some Norwegian coast batteries did not fire at all, or ineffectually, others caused serious destruction.
At Oslo, the heavy cruiser BLÜCHER was heavily damaged and set on fire by two hits from 28 cm guns of the Oscarsborg fortress (plus several hits from a 15 cm battery nearby), and then finished off by land-based torpedoes. Some 350-400 German sailors and soldiers lost their lives.
In the continuing action, the Norwegian batteries scored seven more hits on the LÜTZOW and the BRUMMER (which were next in line), and seriously damaged the latter (later sunk). The Germans were forced to put their main landing force ashore south of Oscarsborg, some 20 miles from Oslo city, and make their approach by land (they arrived in the capital late that night).
To be fair the battle of Dombak narrows was less a conventional ship-vs-CD battery and more a live fire exercise for the Norwegian defense forces. Gruppe Oslo had orders to maintain the ruse of a non-belligerent ally coming to the aid of Neutral Norway, and thus held its fire as it approached the Oscarsborg fortress. By the time the Norwegians opened fire the ship was about a mile away - point blank range for the Norwegian guns.

BTW, Brummer was not part of Gruppe Oslo.
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Re: Sealion compared to historical amphib assaults?

Post by Knouterer » 24 Apr 2018 17:10

The Germans were at a disadvantage, but on the other hand the Norwegians were not too sure what was happening and who was attacking them until almost the last moment, and Oscarsborg was badly undermanned.

The main lesson from this action was IMHO that it was very difficult to suppress coast defence batteries, either from the sea or from the air, as was confirmed on many later occasions.

You're right about the Brummer, don't know how that got into my notes ... that ship did take troops to Oslo, but several days later, on the 15th, and was torpedoed on the way back by HMS Sterlet.
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Re: Sealion compared to historical amphib assaults?

Post by Tsofian » 24 Apr 2018 22:27

Knouterer wrote:The Germans were at a disadvantage, but on the other hand the Norwegians were not too sure what was happening and who was attacking them until almost the last moment, and Oscarsborg was badly undermanned.

The main lesson from this action was IMHO that it was very difficult to suppress coast defence batteries, either from the sea or from the air, as was confirmed on many later occasions.

You're right about the Brummer, don't know how that got into my notes ... that ship did take troops to Oslo, but several days later, on the 15th, and was torpedoed on the way back by HMS Sterlet.
If the Norwegians had been fully ready they would have had their minefields laid and their guns fully manned. Even with that, and with guns that were decades older then the ships they were firing at, the defenses put some serious hurt on the Nazis.

The initial destruction of Blucher was a a worst case scenario for the KM. However the Lutzow was hit by 15 cm batteries several times and had her forward main turret put out of action by the lighter batteries at Oscarborg. The Germans were firing on the batteries and there were also airstrikes targeting them. They maintained their fire and had no guns knocked out.

It was shown many times that airstrikes had a difficult time knocking out coastal batteries. Area fire from warships also generally failed to knock out guns, although they could sometimes force crews to take shelter and suppress the battery for some time. Normandy and other engagements in both the Pacific and Europe showed that to be most effective a warship had to be dedicated to firing at the battery and having some sort of spotting was extremely helpful. Now, that spotting could be from aircraft, or from observers aboard ship or from forward observation teams. Even then getting destructive, rather than suppressive hits on coastal guns is very hard. The other effect that having a ship directly engage a specific battery is that the battery generally engages the ship firing at it, and isn't shooting up the beach or transports but is acting in a self preservation mode. This reduces the impact the battery has on the invasion.

Now batteries could be degraded by area bombing and fire by knocking out observation, communications, fire control, and exhausting, wounding and killing crews. The batteries at Cherbourg and other locations were often heavily degraded before their final engagements (Battery Hamburg vs USS Texas).

The German invasion of England did not have the resource level in terms of fire support see at Tarawa, or Normandy or Sicily or anywhere else, even Dieppe. The German fleet has a hand full of destroyers, which do have 5 inch or 5.9 inch guns and would be about equal to the 6 inch batteries on the coast. However these were, to the best of my knowledge, never tasked with NGFS. The M-35 minesweepers with their pair of 10.5 cm guns will be seriously overmatched by a pair of 5.5 or 6 inch coastal guns. That is of course if the M-35s have any rounds left. The crossing and fending off the Royal Navy may well empty their magazines.

The modified gunboats might well have bigger guns but they have even less sophisticated fire control. The question of other sources of fire control comes up. Were the gunboats netted with the dedicated spotting aerial squadrons? Were even the M-35s? Did any of the beach units have communications with the potential support vessels?

Now at Normandy the inshore destroyers used the fire from troops ashore as an informal method to identify targets, and seem to have done so very effectively. It is possible the German vessels might have adopted similar methods. However one of the things that made US destroyers so effective was the high rate of fire of the 5 inch 38. High rate of fire allows greater ease of correction of aim, as well as allowing to "walk" rounds onto a target. The % inch 38 had a designed rate of fire of 15 rpm, which it achieved. The various 15 cm howitzers to be mounted on the gunboats had rates ashore of 3 to 6 rpm. With the makeshift arrangements, especially ammunition supply, of the weapons would make these rates of fire even more difficult to reach.

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Re: Sealion compared to historical amphib assaults?

Post by Knouterer » 25 Apr 2018 08:01

Taking beach B as an example (again) the German firepower afloat can be summarized as follows, on the not very realistic assumption that everybody makes it across on schedule:

6 (or possibly 7) M35 minesweepers (3. MS-Flottile) with 2x105 mm guns plus 3x20 mm AA.
These ships had 300 rounds (150 per gun) for their main armament. Their ability to engage in naval combat or shore bombardment would be a bit limited initially by the fact that they were each carrying some 100 men of the Vorausabteilungen plus their assault boats and other equipment and the priority was to get those to the beach.

16 or 17 armed trawlers of the 2. and 3. Vp-Flottille with 1 x 88 mm gun (some with 37 mm PAK instead) plus 1x20 mm

8 R-Boote (3. R-Flottille) with 2 x 20 mm guns

8 trawlers of the 11. R-Flottille with 1 or perhaps 2 x 20 mm.

Both these last units also carried parts of the Vorausabteilungen which they needed to get to the beach first.

9 Leichte Artillerieträger (LAT, armed coasters) with 1 x 75 mm field gun (these supposedly carried 300 rounds apiece) plus 2 x 37 mm AA guns (army AA guns)

9 “Herbert ferries” with 1x88 mm Flak (500 rounds apiece, of which 200 AA, 100 AT, and 200 HE with impact fuses – let’s say 100 for the shore bombardment) plus 2x20 mm. These would be on the right flank passing below Folkestone.

7 M16 minesweepers (4. MS-Flottille. with 1x105 mm gun (150 rounds) plus 1 or 2x20mm.

7 armed trawlers (16. MS-Flottille) with each 1x88 mm or possibly 75 mm (naval) gun plus 1x20 mm.

These last two units would arrive with the convoy from Rotterdam a couple of hours after the initial landing so would not be able to give fire support until then.
As noted before, the freighters were largely unarmed (the KM only really got around to that in October, according to Schenk), roughly 1x20 mm on average.

What armament the barges were carrying is a bit hard to figure out. Photos show that many – but by no means all – had a raised wooden gun platform amidships.
We may reasonably assume that barges intended to serve as lighters for the transport ships had none, because they would have been in the way. Similarly, the Type B barges for the submersible tanks probably had none either, because a NCO and radioman had to stand on the prow to guide the tanks by radio, which would have been a bit difficult with a field gun banging away behind them and sending shells right past their ears all the time.
Schenk has various contradictory bits of info on this, but states on page 310 that the 35. ID intended to arm 20 of its barges with captured 75 mm field guns, 15 with Pak (according to one source, 10 Czech 47 mm), light infantry guns (75 mm), or mountain guns (75 mm), 13 with 20 mm Flak and the rest with MGs. The field guns were supposed to have 100 rounds apiece.
That sounds reasonably precise and plausible. The 17. ID apparently planned to install a few more field guns, so let’s assume (just for the sake of argument) some 60 or perhaps even 70 guns of 75 mm caliber on the barges (bearing in mind of course that the lIG and Skoda mountain guns were less powerful than the field guns).
As regards the 75 mm field guns, these were nonstandard and obsolescent captured French and Belgian guns, and were apparently intended to be disposable. No battery organization or vehicles or equipment were foreseen for their further use on land, as far as I know, and ammunition supply was only 100 rounds per gun.

Finally, the tugs (and trawlers) towing the barges. There would (theoretically) be 96 of them and Schenk has a picture of some of them carrying what might be 37 mm Pak covered by tarps. However, since the tugs would cast loose their barges at some distance from the shore (2000-3000 m or so), and then would have to shoot over or through them, I think they can be disregarded as far as shore bombardment is concerned.
We have thus, as a very rough approximation, on a 10 km front, some 120 guns of 75-105 mm calibre firing off 13,000 rounds in the first two hours or so. Taking into account losses and stragglers during the night, 10,000 shells would perhaps be more reasonable. Not very much by WWI standards, and it would mostly be direct, low-angle fire, so troops in trenches or behind substantial cover (dunes, buildings …) would have little to worry about. Lacking any form of fire control, the gunners would shoot at what they could see, so large and visible buildings near the shore like the Imperial Hotel in Hythe would probably attract a lot of fire. Same for the Martello towers. Judging by old postcards &c, most buildings in Dymchurch, Greatstone, Littlestone and down that way look relatively lightly built and might well be blasted apart (in some cases), together with British troops who were imprudent enough to take up positions on the first and second floors before the bombardment was over.
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Re: Sealion compared to historical amphib assaults?

Post by Tsofian » 25 Apr 2018 23:38

Lots of interesting information. Let me see if I can add some extra insite-Please see my comments within
Knouterer wrote:Taking beach B as an example (again) the German firepower afloat can be summarized as follows, on the not very realistic assumption that everybody makes it across on schedule:

6 (or possibly 7) M35 minesweepers (3. MS-Flottile) with 2x105 mm guns plus 3x20 mm AA.
These ships had 300 rounds (150 per gun) for their main armament. Their ability to engage in naval combat or shore bombardment would be a bit limited initially by the fact that they were each carrying some 100 men of the Vorausabteilungen plus their assault boats and other equipment and the priority was to get those to the beach.
The 10.5 cm weapons on the M-35 boats are the only purpose built heavy AAA naval mounts in the fleet. The 150 rounds per gun will not be all point fuzed HE for surface targets. Some of the ammunition in the magazines will have to be anti aircraft ammunition and fuzes. In addition, these ships are dedicated to escorting against Royal Navy surface vessels. The question is how much will be shot off before they even get to the beach. We will not question the wisdom of having a vessel loaded with troops act as a surface combatant as well.

16 or 17 armed trawlers of the 2. and 3. Vp-Flottille with 1 x 88 mm gun (some with 37 mm PAK instead) plus 1x20 mm

It is important to note that these are not Flak 18 mounts, so are a much lower performance weapon. Some were probably not high angle weapons at all. In addition, they lacked full fire control. The Pak 37 AT guns were

8 R-Boote (3. R-Flottille) with 2 x 20 mm guns

8 trawlers of the 11. R-Flottille with 1 or perhaps 2 x 20 mm.

Both these last units also carried parts of the Vorausabteilungen which they needed to get to the beach first.

9 Leichte Artillerieträger (LAT, armed coasters) with 1 x 75 mm field gun (these supposedly carried 300 rounds apiece) plus 2 x 37 mm AA guns (army AA guns)
The Army 37mm was a much better weapon than that of the navy, being a fully automatic run with a high rate of fire. The naval 3.7cm AAA was a wonderful piece of ordnance engineering that went down a dead end lane.
9 “Herbert ferries” with 1x88 mm Flak (500 rounds apiece, of which 200 AA, 100 AT, and 200 HE with impact fuses – let’s say 100 for the shore bombardment) plus 2x20 mm. These would be on the right flank passing below Folkestone.

These were also supposed act in anti-surface roles fending off the Royal Navy, and to provide AAA during the crossing. So how many rounds will still be in the magazines when they get off the coast.

7 M16 minesweepers (4. MS-Flottille. with 1x105 mm gun (150 rounds) plus 1 or 2x20mm.
I think the 10.5 cm on the M16 class were low angle guns only
7 armed trawlers (16. MS-Flottille) with each 1x88 mm or possibly 75 mm (naval) gun plus 1x20 mm.

These last two units would arrive with the convoy from Rotterdam a couple of hours after the initial landing so would not be able to give fire support until then.
As noted before, the freighters were largely unarmed (the KM only really got around to that in October, according to Schenk), roughly 1x20 mm on average.

What armament the barges were carrying is a bit hard to figure out. Photos show that many – but by no means all – had a raised wooden gun platform amidships.
We may reasonably assume that barges intended to serve as lighters for the transport ships had none, because they would have been in the way. Similarly, the Type B barges for the submersible tanks probably had none either, because a NCO and radioman had to stand on the prow to guide the tanks by radio, which would have been a bit difficult with a field gun banging away behind them and sending shells right past their ears all the time.
Schenk has various contradictory bits of info on this, but states on page 310 that the 35. ID intended to arm 20 of its barges with captured 75 mm field guns, 15 with Pak (according to one source, 10 Czech 47 mm), light infantry guns (75 mm), or mountain guns (75 mm), 13 with 20 mm Flak and the rest with MGs. The field guns were supposed to have 100 rounds apiece.
That sounds reasonably precise and plausible. The 17. ID apparently planned to install a few more field guns, so let’s assume (just for the sake of argument) some 60 or perhaps even 70 guns of 75 mm caliber on the barges (bearing in mind of course that the lIG and Skoda mountain guns were less powerful than the field guns).
As regards the 75 mm field guns, these were nonstandard and obsolescent captured French and Belgian guns, and were apparently intended to be disposable. No battery organization or vehicles or equipment were foreseen for their further use on land, as far as I know, and ammunition supply was only 100 rounds per gun.

Finally, the tugs (and trawlers) towing the barges. There would (theoretically) be 96 of them and Schenk has a picture of some of them carrying what might be 37 mm Pak covered by tarps. However, since the tugs would cast loose their barges at some distance from the shore (2000-3000 m or so), and then would have to shoot over or through them, I think they can be disregarded as far as shore bombardment is concerned.
The 37mm PAK in ground combat would be expected to get 45% hits at 2,000 meters. This doesn’t account for a gun on a ship in a seaway. Even if they were able to get shots they aren’t likely to get many hits.
We have thus, as a very rough approximation, on a 10 km front, some 120 guns of 75-105 mm calibre firing off 13,000 rounds in the first two hours or so. Taking into account losses and stragglers during the night, 10,000 shells would perhaps be more reasonable.

I don’t believe that there would be this much ammunition left. The Minesweepers and the Herbert Ferries would have shot off a substantial amount of their ammunition, both against surface and aerial targets.

Not very much by WWI standards, and it would mostly be direct, low-angle fire, so troops in trenches or behind substantial cover (dunes, buildings …) would have little to worry about. Lacking any form of fire control, the gunners would shoot at what they could see,
The Germans and British both intended upon using a lot of smoke. This will make the effect of German fire even less affective. The British fortifications were designed to be bullet proof, but a number of them were quite capable of standing up to fire from 75mm. The 8.8 flak 18 would have torn up any of the British fortifications, as would the newer 10.5 cm guns. The 8.8 cm and 10.5 cm both had good rates of fire. But there is a total of 14 of these 10.5 and 9 Flak 18s. That give 25 really effective pieces on a 10 KM front, in the best case scenario. They are on 16 platforms, if none get shot up on the crossing. I’d be surprised if these guns have 100 rounds per gun left in the magazines.

so large and visible buildings near the shore like the Imperial Hotel in Hythe would probably attract a lot of fire. Same for the Martello towers. Judging by old postcards &c, most buildings in Dymchurch, Greatstone, Littlestone and down that way look relatively lightly built and might well be blasted apart (in some cases), together with British troops who were imprudent enough to take up positions on the first and second floors before the bombardment was over.

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Re: Sealion compared to historical amphib assaults?

Post by sitalkes » 26 Apr 2018 00:23

Tsofian wrote: I think historical precedent for between 10 and 20% hits. Batteries would have 100-200 rounds per gun for the new batteries, I can't recall what a prewar battery had in its magazines, but at least 200 rounds per gun would seem reasonable. This gives a battery between 10 and 40 hits against fully loaded transports.

Also to be noted is that in the case of Wake and Hartlepoole that counterfire from the opposing warships was unable to silence any of the guns, even though those weapons were in open emplacements with no overhead cover.
These had little ammunition, sometimes as few as ten rounds apiece, and some were of calibres long out of production, so their ammunition was old and of uneven quality. That's why they were, in effect, given "don't fire until you see the whites of their eyes" orders. 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.

One of the interesting things I learned about going to Normandy was the fate of the coastal gun fire control tower, which is now a museum. The story goes that a lucky shot went through the embrasure and put it out of action early in the battle, which severely degraded the effectiveness of the guns under its control.

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Re: Sealion compared to historical amphib assaults?

Post by Knouterer » 26 Apr 2018 16:51

I don't think the British would have gone to the trouble of setting up batteries of guns that had "only ten rounds apiece", that wouldn't make much sense. I think we can class those with the "only five rounds per rifle" stories. Of the 6in guns supplied by the Navy, many were of the same type (Mk VII) as already used by the coast artillery since 1898; there were various other Marks of 6in BL guns that were not radically different.

Unfortunately we don't seem to have much in the way of real hard data but a minimum of about 75-100 rpg for September seems a reasonable asumption to me. A certain number of shells and charges, sixteen or so of each, were normally kept next to the guns and the rest in a magazine, preferably underground.

According to the Statistical Digest (“Fighting with Figures”), 39,000 shells for coast artillery were produced in 1939 and 76,000 in 1940. It may be assumed that a considerable part of these were shells for the new twin 6pdrs, which consumed ammo at a very fast rate, but on the other hand there were not yet many of these in service in Sept. 1940 (maybe 20 or so in the entire British Empire). The 12pdr and 4.7in guns had been considered obsolete for some time and it may be assumed that no new ammo (or very little) was being produced for them. If we assume 40,000 rounds (1,000 per barrel) for the twin 6pdrs, that still leaves some 50,000-60,000 new rounds of 6in and 9.2in at the end of September, in addition to whatever was left over from earlier production.
Ammunition of exclusively naval calibres – 4in and 5.5in – should normally not be included in the above production figures. And since HMS Hood was the pride of the Royal Navy, we may assume that there still was a reasonable supply of serviceable ammunition on hand for its 5.5in guns when in 1940 they were removed from the ship and installed at the Mill Point battery at Folkestone, St. Margaret’s at Dover and other places.
Similarly, there is no reason to suppose an acute shortage of 4in rounds for the guns in the emergency batteries (and the lorry-mounted guns).
Maurice-Jones, page 217: “The ammunition for both 9.2 inch and 6 inch guns had been improved during the period between the two wars (…) Armour-piercing shell with base fuses, which had optional delay/non-delay plugs, and H.E. shell with nose fuses for unarmoured vessels or for firing landwards were now the normal coast-defence ammunition”.

WO 199/523 “Coast Batteries R.A. – Formation Of” (June 1940-Aug. 1942) contains a note of June 1941 on the subject of using the coast artillery against beach targets, which states:
“The average ammunition in emergency coast batteries (i.e. those not in the old permanent works) includes 100-150 rounds per gun fuse 44 and 15-30 rounds per gun shrapnel. These are both suitable for beach shooting.”

“Fuse 44” refers to the standard nose fuse for H.E. shells. Add a few dozen A.P and/or C.P.B.C. rounds and the total per gun comes up to about 150-250 rounds. It is of course possible that the ammunition supply was increased dramatically over the winter 1940/41, but it doesn’t really look that way. According to the Statistical Digest, the production of coast defence shells actually fell off in the first quarter of 1941; total production in 1941 was 70,000 shells against 76,000 in 1940, according to this source. As regards ammunition from naval sources, WO 199/1123 about “Stores & Equipment for Emergency Batteries” (June 1940 –Aug 1943) has as a constant theme, from about the end of 1940, that the Royal Navy is involved in (at times desperate) fighting all over the world and that therefore the emergency batteries have (very) low priority for spare parts for naval equipment. I would imagine the same applied to ammunition.

The permanent defences at places like Dover were in any case well supplied with ammunition it seems. In July 1940 holdings were reported as follows:

9.2" 250 APC and 25 HE
6" 500 CPBC and 25 HE
4.7" 500 SAP
12pdr 500
6pdr-twin 2000

It was proposed to adjust these scales, over time, as follows:

9.2" 100 APC and 175 HE
6" 200 CPBC and 300 HE
4.7" 500 HE

In other words, less armour-piercing and more HE ammunition, reflecting the expectation (I suppose) that - the memory of Hartlepool and Scarborough notwithstanding - the Germans were unlikely to use their battleships and battlecruisers to attack ports.
Last edited by Knouterer on 26 Apr 2018 17:38, edited 4 times in total.
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Knouterer
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Joined: 15 Mar 2012 17:19

Re: Sealion compared to historical amphib assaults?

Post by Knouterer » 26 Apr 2018 17:07

A little picture showing the positions of the three emergency batteries installed at Folkestone. The Folkestone East and Folkestone West batteries (Nos.338 and 339 respectively) had two 6in guns each. The white Martello tower serving as battery observation post for the FE battery is just visible. 412 Battery at Mill Point, nearest the camera, was armed with four 5.5in guns (max range 16,250 m) which had been removed from HMS Hood a few months previously, was up on a cliff and seems to offer an excellent view of the whole affair, and (part of) the transport fleet after it had dropped anchor would be well within range.
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"The true spirit of conversation consists in building on another man's observation, not overturning it." Edward George Bulwer-Lytton

Knouterer
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Posts: 1482
Joined: 15 Mar 2012 17:19

Re: Sealion compared to historical amphib assaults?

Post by Knouterer » 26 Apr 2018 17:16

However, when I went there in September 2016 I noticed that you can't actually see anything from the gun positions. I stood where the far right gun (No. 1) must have been and I couldn't see Hythe or the beach beyond, not even when I took several steps forward towards the cliff edge. Any vegetation blocking the view would have been cut down in 1940 of course, but what is not so apparent from maps and aerial pics is that the ground rises slightly in that direction.
It follows that the battery observation post (see map) must have been in some kind of tower or elevated structure, just behind the gentleman with the walking stick, making it vulnerable to air attack.
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"The true spirit of conversation consists in building on another man's observation, not overturning it." Edward George Bulwer-Lytton

Tsofian
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Re: Sealion compared to historical amphib assaults?

Post by Tsofian » 26 Apr 2018 22:55

Knouterer wrote:I don't think the British would have gone to the trouble of setting up batteries of guns that had "only ten rounds apiece", that wouldn't make much sense. I think we can class those with the "only five rounds per rifle" stories. Of the 6in guns supplied by the Navy, many were of the same type (Mk VII) as already used by the coast artillery since 1898; there were various other Marks of 6in BL guns that were not radically different.
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Batteries were emplaced all along the coasts. I wonder if the batteries closest to the possible invasion locations might have gotten more ammunition sooner?

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