Sealion Naval Forces

[MattII]

Is that with or without the RN being on high alert after having noticed a buildup of barges for three days preceding their actual setting off? Also, 'even travelling at 5kn' is an interesting phrase, the barges could probably do it, but there's also the current to think about, and through the strait it's a bit of a ripper at full flow, so given the top speed of the barges is somewhere in the region of about 6 kn, if the current's passing through they're not going to be doing anything like 6 kn.

 

[Saphroneth]

is that with or without the RN beoing on high alert after having noticed a buildup of barges for three days preceding their actual setting off? Also, 'even travelling at 5kn' is an interesting phrase, the barges could probably do it, but there's also the current to think about, and through the strait it's a bit of a ripper at full flow, so given the top speed of the barges is somewhere in the region of about 6 kn, if the current's passing through they're not going to be doing anything like 6 kn.

This is why we have a friggin' sealion reference thread. Anyone volunteering to go find that bit which confirmed that, for the Brits to be taken by surprise, they'd have to not have eyes?
(This is one of the many reasons Overlord went better - the number of ports to be used for Overlord was VAST, and they were out of sight of the mainland. By contrast, the Germans have to cram their forces into a tiny area to provide even some measure of naval cover.)

 

[King Augeas]

And in those 7 3/4 hours even travelling at 5kn the barges will have made it across the Channel and if the crossing is at night it will then be daylight with the added dangers that poses ... I'm only interested in ships that would have been available in the first clashes. After that the RN are going to have their mediums and heavies available and will undoubtedly win the day.

Wasn't there some source posted recently that talked of the barges taking days to leave the harbour and form up in sight of Dover?

 

[MattII]

Indeed there was, right here. That was on page 29, the drivel of a few twits trying to defend the indefensible continued for another fifteen-and-a-bit pages. Also got a link to a glossary of RN assets in mid September.

If you count everything within 4 hours of the beaches you end up with:
19 MTB
5 TB
40 DD
3 CL

And that's just the professional vessels, that doesn't include militarised civilian vessels such as trawlers with guns bolted on.

 

[sitalkes]

Few comments:

• Numbers! I can't see how many of each type there are - fifty RN destroyers is a very different proposition from two, but you can't tell from that list (that or I'm just blind ).
• It would be really good to have some idea of how far away all the vessels are, say from a nominal point on the British coast like Hastings. Distance is OK, time at a plausible speed is better (assuming the Germans get picked up halfway across). Say if you banded into "first 3 hours", "first 12 hours", "first 24 hours" and "first 48 hours".
• For some reason I thought that there were RN cruisers at Southampton and the Nore/Harwich - am I wrong, or are you counting them as too far away?

This has been done in Geoff Hewitt's book "Hitler's Armada" and in Fred Leander's book "River Wide, Ocean Deep" - they have opposite points of view but come up with similar destroyer numbers. Yes there were light cruisers to lead each destroyer flotilla (I think a total of seven IIRC though some of the light cruisers weighed 10,000 tons)

 

[sitalkes]

Wasn't there some source posted recently that talked of the barges taking days to leave the harbour and form up in sight of Dover?

No, it's a maximum of 9.5 hours (check the reference on that link) or its none (because the convoy leaves 8.5 hours before S hour) or in Walter Ansell's diagram it says it's one hour- For one of the four convoys. Two of the convoys don't even go through the Straits of Dover.

 

[Saphroneth]

No, it's a maximum of 9.5 hours (check the reference on that link) or its none (because the convoy leaves 8.5 hours before S hour) or in Walter Ansell's diagram it says it's one hour- For one of the four convoys. Two of the convoys don't even go through the Straits of Dover.

When is it they lock through into the outer harbour at Calais? That's at least going to get people on alert.

 

[King Augeas]

No, it's a maximum of 9.5 hours (check the reference on that link) or its none (because the convoy leaves 8.5 hours before S hour) or in Walter Ansell's diagram it says it's one hour- For one of the four convoys. Two of the convoys don't even go through the Straits of Dover.

Where do these numbers come from? Cracou's post stated:

"The two groups which formed in Calais by S Day minus 2 would load their troops and set sail at 1000hrs on S Day minus 1.
"All of the tows and the heavy pontoon ferries were to anchor in the assembly area off Calais on S day minus 1 at 1700hrs at the latest.
"Given an estimated rate of 15 tows leaving the harbour each hour, it would have taken the ten hours for the fleet to leave Boulogne. Therefore assembly was to commence on S minus 2 at 1200 hours. Once assembled the fleet would depart on S day minus 1 at 1600hrs.
"The KMD 55 estimated that it would take the advance detachment 55 hours, and the convoys 72 to leave Le Havre.
"In Rotterdam, loading was to start on S Day minus 6 and end on S day minus 4. The fleet was to sail on S day minus 2."

 

[King Augeas]

Ah I think it's here. https://www.alternatehistory.com/discussion/showthread.php?t=318201&page=40

Some are still crowing about a 2-4 day wait off Calais, having not bothered to read my previous post or even look at the map, so once again I refer you to post https://www.alternatehistory.com/discussion/showpost.php?p=9340598&postcount=646

This shows that only one of the invasion fleets out of three would be waiting off Calais, and even that is not necessarily supported by the full text.

M M Evans has a different map, viz:

Page 205

“Map 1 on pages 226-7 shows the routes as established by the Naval Commander West for 14 September 1940. Towed formation 2 from Ostend had to sail 43 nm to the beginning of Route 1, where it was added to Tow Unit 1 which had come 19 nm from Dunkirk. In order for these forces to rendezvous successfully on the evening of S minus 1, the vessels from Ostend had to leave on the morning of S minus 1 day, and those from Dunkirk that afternoon. Transport Fleets B and C would have crossed the Dover straits by daylight, thus ruling out the chance of a surprise attack; and the British forces would have had the advantage of daylight to launch a counter offensive."
Route 4 (the Green Route) would have been used for the initial crossing only, after that reinforcements for Beach E would land on Beach D.

"Tidal charts were scrutinised in planning the routes. The tow units would have to sail against the tide for only a short time and after the course change the tide would increase their cruising speed by about 1 to 1.5 knots. By the time the tide had changed again the formations would have just about reached the markers for the course change directly into the shore.”

I have had some trouble working out what was supposed to happen with Fleet C, as it says above they were to rendezvous on the evening of S minus 1 but they were going to cross in daylight. On another page, it says that Fleet C would leave port at 8.5 hours before S-day, which also seems to indicate they would be leaving in the evening. If S-time was 6am then they would be leaving at 9.30pm, with little if any daylight left. Then comes this weird mixture:

“The tow groups which form in Calais by S Day minus 2 would load their troops and set sail at 1000hrs on S Day minus 1. In Gravelines this process started at 0500 hours on S Day minus 1 in order for these tow groups to reach the assembly area off Calais harbour by 0700 hrs… All of the tows and the heavy pontoon ferries were to anchor in the assembly area off Calais on S Day minus 1 at 1700 hrs at the latest…. The transport fleet commander was to board his own command boat at 1300 hrs the next day as the fleet was sailing. At S day minus 11 hours the 4th R-Boat Flotilla weighed anchor and began sweeping Route 2… At S Day minus 10 ¾ hours the transports would weigh anchor after a radio signal and wait another quarter of an hour until the head of the fleet, led by the command boat, got underway at a speed of 3 knots. The remaining tows with the barges now closed up behind one another were to close up and follow in sequence (see Map 4). After an order via radio an hour later, speed was to be increased to 5 knots.”

This seems to indicate that the tow groups would start forming at 7 or 10am and leave at 5pm. (which is 7-9 hours not even a full day, but still pretty alarming) The transport fleet commander sentence makes no sense at all! I think I will have to see if I can contact Peter Schenk and ask for a clarification.

Possibly the fleet was to wait under the cover of the Channel Guns, which would have been much more effective and numerous at that close range. The navy commander says in his orders that he expects to see full air superiority resulting in only an odd bomber or fighter getting through so perhaps he doesn't think waiting a while will result in total destruction of this part of the fleet under those conditions.

It should be noted that the "Cromwell" code word was issued when no invasion was taking place or was even immanent as the codeword suggested. It took until September 7 for the British to even realise the invasion was on the south coast, not the east coast. It was obviously hard for them to tell what actually was going on as there were so many movements down the coast, and invasion practices (including embarkation and disembarkation) that were occurring.

This is easily rebutted. It doesn't matter how many fleets are forming elsewhere, as soon as one is seen leaving Calais then an alert is sounded. Anyway, the source has fleets crossing in daylight.

The Channel guns were generally ineffective. They would certainly be ineffective as soon as any RN vessels got among the barges. No air superiority is available at night. Both of these factors make a daytime crossing sensible, but then you throw away any chance of surprise and you still can't defend the barges that night of the English coast.

 

[Saphroneth]

You know, I have to wonder if the Brits (being the ones with amphibious experience, and if anything overestimating the chances of a given amphib operation as per Gallipoli or Dieppe) dismissed the idea of a south coast invasion because it was completely, unutterably, ridiculous. Meanwhile, the east coast option, with a better chance of actually doing some damage, was considered the more likely threat.

 

[King Augeas]

You know, I have to wonder if the Brits (being the ones with amphibious experience, and if anything overestimating the chances of a given amphib operation as per Gallipoli or Dieppe) dismissed the idea of a south coast invasion because it was completely, unutterably, ridiculous. Meanwhile, the east coast option, with a better chance of actually doing some damage, was considered the more likely threat.

I vaguely remembering reading somewhere that that was the exact fear. An East Anglia landing could achieve surprise, particularly with a Channel diversion. It could disgorge panzers on to good tank country and strike east to cut the main railway lines.

I'm not sure what happens after the RN shells the landing zones into ruin though.

 

[Ian Hathaway]

RN Ship Numbers

According to naval-history.net and the relevent War Cabinet minutes for the period on the night of 23/24 September there were 94 Destroyers, 10 Light Cruisers and 2 Heavy Cruisers in British waters. Once you remove those that were on active convoy duties the number of Destroyers falls to 74. These figures do not include ships that were undertaking refit or repairs. Of those 74, 10 were on patrol and 1 was escorting minelaying operations.

Only ships stationed between Harwich and Portsmouth would have been available to attack within three hours, calculated by distance from Dover in the East and Brighton in the West and assuming a speed of 30kn (Even though some of the Destroyers involved only had a top speed of 29kn). This amounts to 23 destroyers including four on patrol and the minelaying escort as these operations were close enough to allow them to get to the danger area in time.

Only ships stationed at Immingham and Plymouth would have been able to get to the danger area in 12 hours or less. This amounts to another 13 Destroyers including 6 that were on patrol off the Brittany coast as part of Operation GL.

The remaining 38 Destroyers were stationed at Belfast, Clyde, Liverpool, Methil, Rosyth, Scapa and the Tyne.

There were 3 Light Cruisers stationed at Immingham and 2 at Plymouth ... it is highly likely that one or two of these would have been moored overnight at Sheerness or Portsmouth so that would make 2 Light Cruisers within 3 hours, 2 more within 12 hours and the remainder available at about the 24 hour mark.

Going back to the 23 Destroyers that would have been in the first wave there were 2 Campbell Class, 12 V&W, 3 B Class and 6 Hunt Type 1's. The Campbells were well armed and fairly heavy, the V&W were a mix of armament (see attached list), the B's were similar to the V&W and the Hunts were light escort Destroyers (again see attached list).

 

[Saphroneth]

...and, to put that in perspective, the quick-reaction force is...
2x1580 tonnes (Admiralty type Flotilla leader)
12x1360 tonnes (V&W)
3x1380 (B class)
6x1020 (Hunt I)
plus about 10,000 tonnes of CL.

Which adds to about 40,000 tonnes of ship. I'm discounting light forces on both sides, where the RN has an advantage.

The German pocket BB, CA and CL forces add to about 45,000 tons of ship, and their DDs presumably about another 10-15 tonnes. Which means that the complete German navy at this point is only about 50% larger than the RN quick reaction force.
This is not a recipe for success protecting a convoy, especially as the "slow" reaction force is on the order of making up the balance entirely, while the largest German ships were going to be used as decoys. (If we remove the decoy ships from the equation, assuming that they're sailing in circles shouting rude words at Home Fleet, then the QR force alone actually outmasses what of the German navy will be present by about 33%.)

 

[Ian Hathaway]

Lets Try This Again

...and, to put that in perspective, the quick-reaction force is...
2x1580 tonnes (Admiralty type Flotilla leader)
12x1360 tonnes (V&W)
3x1380 (B class)
6x1020 (Hunt I)
plus about 10,000 tonnes of CL.

Which adds to about 40,000 tonnes of ship. I'm discounting light forces on both sides, where the RN has an advantage.

The German pocket BB, CA and CL forces add to about 45,000 tons of ship, and their DDs presumably about another 10-15 tonnes. Which means that the complete German navy at this point is only about 50% larger than the RN quick reaction force.
This is not a recipe for success protecting a convoy, especially as the "slow" reaction force is on the order of making up the balance entirely, while the largest German ships were going to be used as decoys. (If we remove the decoy ships from the equation, assuming that they're sailing in circles shouting rude words at Home Fleet, then the QR force alone actually outmasses what of the German navy will be present by about 33%.)

As I said in the opening post of this thread ...

Please note this is NOT a "the Germans had this so they could defeat the RN"

Please don't turn this into an argument if you can help it, this thread is here purely to try to gain knowledge ... Thanks.

I could be wrong but it would appear that you haven't even looked at the attached document and are therefore assuming too much and possibly jumping up and down with your boxing gloves on without having an idea of what this thread is fully about. If you haven't viewed the document please do before you comment again.

 

[Saphroneth]

As I said in the opening post of this thread ...

Please note this is NOT a "the Germans had this so they could defeat the RN"

Please don't turn this into an argument if you can help it, this thread is here purely to try to gain knowledge ... Thanks.

I could be wrong but it would appear that you haven't even looked at the attached document and are therefore assuming too much and possibly jumping up and down with your boxing gloves on without having an idea of what this thread is fully about. If you haven't viewed the document please do before you comment again.

Yes, I've viewed the document.
However, given that, to put it bluntly, you have previous (i.e. you start a sealion thread every other month or so) then it nevertheless bears restating.
I mean, you have in the past accused me of "crystal ball syndrome" for assuming that the Royal Navy will notice hundreds of barges locking through into the outer reaches of a port they can actually see with the naked eye.

Hell, you're doing it again here - you have "three hours warning" as the quick reaction force, whereas you have previously said that the Brits would have a patrol 10 miles off the coast (that is, in the middle of the channel, halfway across). This means that, for the Brits to have three hours between "they notice the enemy" and "the enemy reached Britain", they would have to not notice the invasion fleet until they literally bumped into it!

(To summarize - three hours is a bit of a low estimate for the potential reaction time for the QR force.)

 

[Ian Hathaway]

Yes, I've viewed the document.

Okay well you say you have so I guess I’d best believe you although some of your comments in this thread would suggest otherwise. For instance your guesstimate of German naval tonnage at 10-15,000 t indicates to me that you haven’t looked at the document or at best looked at it but ignored it, as each Destroyer displaces over 3,000, the tenders, minelayers and mine detonators which are specifically mentioned as being earmarked for Sealion range from 1,800 to 7,500 t. Even if only one of each type is involved that’s more than 28,000t. And that’s not including the torpedo boats or escorts that in themselves are heavier and better armed than some of the RN Destroyers. Anyway, I stand corrected you say you have looked so I must assume now that you have.

However, given that, to put it bluntly, you have previous (i.e. you start a sealion thread every other month or so) then it nevertheless bears restating.

I have been on this site for 18 months and in that time I have only created 3 threads relating directly to Sealion and one of those was more about the BoB than Sealion. If it was every other month it would be 9 Sealion threads. So it might be possible that you are exaggerating slightly.

I mean, you have in the past accused me of "crystal ball syndrome" for assuming that the Royal Navy will notice hundreds of barges locking through into the outer reaches of a port they can actually see with the naked eye.

Shall we put this into a little bit of context … you are referring to a question I posed on the Sealion Sticky which funnily enough is more or less the question I am asking in this thread, something you would not comment directly on then either. From the Sealion Sticky:-

So, in other words, if the RN does exactly what would minimize their own advantage and maximize that of the Kriegsmarine, then the Kriegsmarine will do better than a basic comparison will indicate.

Okay... no argument here.

The question is, why should the RN (who will have literally days of warning) straggle in piecemeal and allow the Kriegsmarine to act to best advantage?

You appear to suffering from crystal ball syndrome, i.e. the British will know immediately when, with what and where the Germans are planning to land.

OTL throughout September there were constant reports of shipping movements along the French coast, the codeword "Cromwell" (the highest level of invasion alert) was issued on the 8th September and stayed in place for a good 10 days and the British reaction was not to panic and send every available destroyer to attack. In fact during the 247th meeting of the War Cabinet on 11th September the following discussion took place:-

The British reaction was actually to attack the concentrations of barges from the air and maintain a Destroyer patrol at night 10 miles or so from the French coast so that they could intercept the invasion fleet once it was underway. When I talk about the first half a dozen or so RN Destroyers it's the ones that are on patrol, the ones that will make first contact.

However, this still doesn't answer my question which is how effective the TB's, Escorts, MB's and even the S-Boats would be against RN Destroyers. I'm trying to gauge how this would affect RN tactics, would they be comfortable sending groups of 4-6 destroyers in or would they prefer to send in more concentrated groups?

You kind of ignored the points I was making then as well i.e. The British didn’t have three days warning they had 2 or 3 weeks warning and they reacted in the best way that they could. BUT they were not going to risk attacks on enemy harbours because they were protected by artillery, mines and patrol boats. Better to wait for the invasion to be launched and hit them at sea where they were less well protected. The crystal ball syndrome refers to the fact that you seem to think the British knew the German plans off by heart … the transport routes, the invasion beaches, the scale of forces, the number of escorts etc. etc. and would head straight for the best place to attack.

Hell, you're doing it again here - you have "three hours warning" as the quick reaction force, whereas you have previously said that the Brits would have a patrol 10 miles off the coast (that is, in the middle of the channel, halfway across). This means that, for the Brits to have three hours between "they notice the enemy" and "the enemy reached Britain", they would have to not notice the invasion fleet until they literally bumped into it!

(To summarize - three hours is a bit of a low estimate for the potential reaction time for the QR force.)

And here … I’m not quite sure what your point is. I don’t have “three hours warning” for anything … another user (pdf27) made a suggestion that it would be nice to know where the British forces were stationed and give a banding based on time; that’s all I did. See below, or read the full thread properly …

Few comments:

• Numbers! I can't see how many of each type there are - fifty RN destroyers is a very different proposition from two, but you can't tell from that list (that or I'm just blind).
• It would be really good to have some idea of how far away all the vessels are, say from a nominal point on the British coast like Hastings. Distance is OK, time at a plausible speed is better (assuming the Germans get picked up halfway across). Say if you banded into "first 3 hours", "first 12 hours", "first 24 hours" and "first 48 hours".
• For some reason I thought that there were RN cruisers at Southampton and the Nore/Harwich - am I wrong, or are you counting them as too far away?

As for patrols I think I may have mentioned those here …

According to naval-history.net and the relevent War Cabinet minutes for the period on the night of 23/24 September there were 94 Destroyers, 10 Light Cruisers and 2 Heavy Cruisers in British waters. Once you remove those that were on active convoy duties the number of Destroyers falls to 74. These figures do not include ships that were undertaking refit or repairs. Of those 74, 10 were on patrol and 1 was escorting minelaying operations.

Only ships stationed between Harwich and Portsmouth would have been available to attack within three hours, calculated by distance from Dover in the East and Brighton in the West and assuming a speed of 30kn (Even though some of the Destroyers involved only had a top speed of 29kn). This amounts to 23 destroyers including four on patrol and the minelaying escort as these operations were close enough to allow them to get to the danger area in time.

Only ships stationed at Immingham and Plymouth would have been able to get to the danger area in 12 hours or less. This amounts to another 13 Destroyers including 6 that were on patrol off the Brittany coast as part of Operation GL.

The remaining 38 Destroyers were stationed at Belfast, Clyde, Liverpool, Methil, Rosyth, Scapa and the Tyne.

There were 3 Light Cruisers stationed at Immingham and 2 at Plymouth ... it is highly likely that one or two of these would have been moored overnight at Sheerness or Portsmouth so that would make 2 Light Cruisers within 3 hours, 2 more within 12 hours and the remainder available at about the 24 hour mark.

Going back to the 23 Destroyers that would have been in the first wave there were 2 Campbell Class, 12 V&W, 3 B Class and 6 Hunt Type 1's. The Campbells were well armed and fairly heavy, the V&W were a mix of armament (see attached list), the B's were similar to the V&W and the Hunts were light escort Destroyers (again see attached list).

Now this will be the last time I respond to anything that isn't directly related to the thread, I'm looking for comments on the relative effectiveness of the various kinds of German ships against those of the RN, nothing more, nothing less. Thank you.

 

[ivanotter]

... and Overlord took some 6,500 ships. Just to put it into perspective.

Ivan

 

[MattII]

I'd also like to say that that list only gives ship classes, it doesn't split them between British and German types.

 

[TFSmith121]

Um, no, actually...under the designations commonly used,

as each Destroyer displaces over 3,000, the tenders, minelayers and mine detonators which are specifically mentioned as being earmarked for Sealion range from 1,800 to 7,500 t.

Um, no, actually...under the designations commonly used, any warship of more than 3,000 tons displacement was a cruiser, not a destroyer, espoecially if armed with a main battery greater than 5 inch/127 mm weapons (see HNMS Tromp for an example), and I would be very surprised if any of the KM's actual destroyers had standard displacements of more than 3,000 tons.

Tenders and mine warfare vessels (with the limited exception of the built for the purpose ocean-going minelayers like HMS Abdiel or USS Terror) were generally not regarded as warships, since they tended to be converted merchant ships, or based on merchantile designs. They were generally regarded as auxiliaries, along with oilers, transports, and the like...hence the "AM" hull designations in the USN, for example, for minesweepers.

If one really wants to suggest a cross-channel steamer refitted as the equivalent of one of the RN's ocean boarding vessels, or an passenger-cargo ship refitted as the equivalent of one of the RN's armed merchant cruisers, was a warship, one can - but it basically begs the issue of why the RN equivalents would not be considered in the mix as well.

And it avoids the fact that such merchantile conversions were, basically, unfit to meet any sort of designed for the purpose warship; my favorite example is the action of the IJN merchant cruisers Aikoku Maru and Hokoku Maru against HMIS Bengal and the tanker Ondina.

Another example is the fact that even a merchant freighter with a naval armed guard party, if handled well by her merchant marine crew, could defeat an armed merchant cruiser (with consort) with a naval crew; favorite example there is the SS Stephen Hopkins against the KM merchant cruiser Steier and oiler Tannenfels.

Bottom line, there's a reason armed merchantmen have not been considered the equal of a warship since the 1500s...

They aren't.

Best,

 

[larpsidekick]

Um, no, actually...under the designations commonly used, any warship of more than 3,000 tons displacement was a cruiser, not a destroyer, espoecially if armed with a main battery greater than 5 inch/127 mm weapons (see HNMS Tromp for an example), and I would be very surprised if any of the KM's actual destroyers had standard displacements of more than 3,000 tons.

Tenders and mine warfare vessels (with the limited exception of the built for the purpose ocean-going minelayers like HMS Abdiel or USS Terror) were generally not regarded as warships, since they tended to be converted merchant ships, or based on merchantile designs. They were generally regarded as auxiliaries, along with oilers, transports, and the like...hence the "AM" hull designations in the USN, for example, for minesweepers.

If one really wants to suggest a cross-channel steamer refitted as the equivalent of one of the RN's ocean boarding vessels, or an passenger-cargo ship refitted as the equivalent of one of the RN's armed merchant cruisers, was a warship, one can - but it basically begs the issue of why the RN equivalents would not be considered in the mix as well.

And it avoids the fact that such merchantile conversions were, basically, unfit to meet any sort of designed for the purpose warship; my favorite example is the action of the IJN merchant cruisers Aikoku Maru and Hokoku Maru against HMIS Bengal and the tanker Ondina.

Another example is the fact that even a merchant freighter with a naval armed guard party, if handled well by her merchant marine crew, could defeat an armed merchant cruiser (with consort) with a naval crew; favorite example there is the SS Stephen Hopkins against the KM merchant cruiser Steier and oiler Tannenfels.

Bottom line, there's a reason armed merchantmen have not been considered the equal of a warship since the 1500s...

They aren't.

Best,

The 1934 and all 1936 classes of destroyer were all above 3000 t and with 5in guns - but were also poor sea boats, with the 1934s being worse. As you rightly point out, size isn't everything!