Operation Sealion

[Peter89]

If the British got some whiff what was up, photo reconnaissance of loading, there is plenty of scope for a brutal Turkey shoot. The Kreigamaine was unwilling to commit any major fleet units to the invasion, all those would be in a "diversion" in the North Sea (my reading it was the German Navy saving it's major assets from potential disaster)

The "major fleet units" they could commit consisted of Emden, Köln, Nürnberg, and Bremse. Three light cruisers and an armed training ship. Otherwise, it was Z4, 5, 6, 10, 14, 15, 16, 20, and possibly 26...a mighty host indeed.

While in general I agree with your point, your data is incorrect.

Admiral Scheer was ready for combat on July 27
Prinz Eugen was ready for combat on August 1

Not as if they would change the picture.

Prinz Eugen, not that Ready for combat. Was undergoing sea trials then final medications. was no passed for combat till April. Yes it could have been thrown in without sea trails, finial modifications or a trained crew, but that not generally how things were done.

https://en.wikipedia.org/wiki/German_cr ... rinz_Eugen

"Commissioning was delayed slightly due to light damage sustained during a Royal Air Force attack on Kiel on the night of 1 July 1940. Prinz Eugen suffered two relatively light hits in the attack,[9] but she was not seriously damaged and was commissioned into service on 1 August.[8] The cruiser spent the remainder of 1940 conducting sea trials in the Baltic Sea.[6] In early 1941, the ship's artillery crews conducted gunnery training. A short period in dry dock for final modifications and improvements followed.[11] In April, the ship joined the newly commissioned battleship Bismarck for maneuvers in the Baltic. The two ships had been selected for Operation Rheinübung, a breakout into the Atlantic to raid Allied commerce."

I counted in the Prinz Eugen because she was the third ship of her class. Sea trials are kinda different when it comes to a new kind of ship with a new layout, a new propulsion and new guns and when it comes to a ship which is identical to those that have been used before. Had there been a really pressing need for the invasion of England, the fully trained crew of Admiral Hipper could operate the Prinz Eugen. (Crew transfers after the Weserübung was not unheard of, eg. some of the crew of the Bismarck was originally deployed on Karlsruhe).

So I left out the Bismarck on purpose, although she was commissioned on 24th August.

[aurelien wolff]

how could they make it work? (I don't think it could work)
https://youtu.be/YnPo7V03nbY

[glenn239]

Just to follow up on this notion that the "German army" could "whip up" a "Plan B" at a moments notice...

At the beginning of 1940, the German merchant marine consisted of:

433 Dampfer (steamers) of between 100 and 1,000 GRT. Another 4 were acquired during the year (built or seized), but 20 were lost. After considerable effort over three months, 164 of those were accumulated for SEELÖWE by the end of September 1940...so about 40 percent of what was available.

For larger vessels, the German merchant marine had:
480 of 1,000-3,000 GRT (plus 4 acquired, minus 29 lost);
185 of 3,000-5,000 GRT (plus 0, minus 24 lost);
146 of 5,000-7,000 GRT (plus 1, minus 41);
165 of 7,000 GRT or larger (plus 5, minus 24).

Of those, 168 of roughly 760,000 GRT were accumulated for SEELÖWE...so about 20 percent of what was available. Another 13 were converted to Sperrbrecher. Another 128 were lost in 1941, of which 7 were replaced. Another 64 were lost in 1942, of which 8 were replaced. All of 46 were built from 1943 to war end, but 409 were lost.

They were a finite resource.

The ones of special interest in Sealion were those with the smaller displacement, ie, 100 to 3,000 tons. The conditions inherent to the Channel, (RN naval superiority or supremacy, contested in the air) meant that any transports actually employed could not spend more than a few hours unloading on the British side before retreating back to France. The debarkation of supplies (tons per hour) is a fiddly subject, but a reasonable guess might be a large well fed team of stevedores might debark 100 tons per hour over the beach? If 2 hours unloading is a reasonable figure, then perhaps 200 tons supply per trip is in the ballpark. 200 tons is not something a 5,000 ton ship should be doing. If the RN is exchanging cruisers and destroyers lost for 5,000 ton ships, that's a game it wants to play. If its losing scarce warships for 100 ton scows, that's a game it does not want to be playing.

Assuming a bridgehead of 15 division requiring 100 tons each in static positions per day, that would be 1,500 tons, or about 7 supply ships, plus whatever the Luftwaffe brings in. 7 supply ships * 30 days is 210 runs. An exceptional attrition rate for the British to inflict would be 30%, or about 70 per month.

So, assuming the highest army industrial priority, could the Germans build 70 Siebel ferries and MFP's per month? It's only 14,000 tons of shipping.

The MFP-A, MFP-B, and MFP-C were not "mass produced". They were produced in a large number of yards, but with generally small numbers produced by old school construction methods in each yard. The MFP-D was designed in 1941 for sectional construction and mass production.

The small numbers produced will be indicative of the labor and steel priorities committed, which in turn will reflect the fact that after November 1940, specialised channel landing craft would not be needed to invade Russia. An early figure for Liberty ships I see in googling was 1.2 million man hours per ship, or about 85 man hours per ton. Applying that to a 200 ton MFP and rounding up, that figure might be something about 20,000 man hours per MFP, (less for a Siebel Ferry). At 50 hours per worker per week, that's a work force of 20,000 needed to turn out 200 per month if using German labour. An additional 3,000 would be required as crew and maybe another 5,000 for logistics support for each month's production, (ie, one demobilized army division to meet every 6 weeks of production).

[glenn239]

Yes, given the Nore Command at Immingham alone had CL Manchester, Birmingham, and Southampton, with CL Galatea and Aurora at Sheerness, and 38 DD and 7 sloops divided between the two and Harwich, I doubt adding either or both would change the picture.

What is the expected attritional results (total number of kills) that 5 RN light cruisers, 38 destroyers and 7 sloops could achieve under average expected night fighting conditions in the Channel in September 1940, assuming no German escorts at all?

[Richard Anderson]

The ones of special interest in Sealion were those with the smaller displacement, ie, 100 to 3,000 tons.

If they were of special interest, why was the average size of the 168 accumulated specifically for SEELÖWE 4,524 GRT? There may be something wrong with your assumptions.

The small numbers produced will be indicative of the labor and steel priorities committed,

Again that is your assumption. It is just as likely that the small numbers produced were indicative of the small number and capability of the boat yards they were built in.

which in turn will reflect the fact that after November 1940, specialised channel landing craft would not be needed to invade Russia.

And yet, oddly enough, they were built and used in the invasion of Russia [sic]. Where do you suppose the 83-odd built at Varna were employed?

[Richard Anderson]

What is the expected attritional results (total number of kills) that 5 RN light cruisers, 38 destroyers and 7 sloops could achieve under average expected night fighting conditions in the Channel in September 1940, assuming no German escorts at all?

I have no idea, since that has zero to do with the point I was actually making, but if it interests you so much why don't you game it out?

[Gooner1]

What is the expected attritional results (total number of kills) that 5 RN light cruisers, 38 destroyers and 7 sloops could achieve under average expected night fighting conditions in the Channel in September 1940, assuming no German escorts at all?

"The Nore flotillas cruisers would overhaul the steamers first. British naval radar was not very clever in 1940, but it could hardly fail to pick up a crowd of such shipping. If the wind was blowing up-Channel, it might even be possible for the Salt Horses to smell the sulphurous smoke pumping out of so many funnels.

These steamers were merchant ships. There had been no time to armour them. Some carried a few machine guns or pieces of small-calibre artillery, meant for the beaches. The ships would be heavily laden with troops, tanks, artillery, horses and all the thousand stores an invading army needs, from bullets to stretchers.

The steamers were best left to the three light cruisers out of Sheerness. Each had 6-inch guns. Some had four 4-inch guns, some had eight. Their first salvoes would set ablaze enough steamers to illuminate the others. After that the ships would be sunk as fast as the crews reload.
This could not be called a battle. To defend Fleet B, the German navy only had two destroyers and some E-boats, based at Ostend. If they escorted the steamers and turned on the cruisers, they would find themselves outgunned by the bigger ships and outnumbered by twenty British destroyers.

The slaughter of the steamers would have the grim, lopsided, brutal efficiency of an abattoir. They were defenceless. They did not have the speed to scatter. Within minutes, many would be holed, listing, sinking, burning. The sea would be a tangle of barges, some cast off, some dragged down by the mother ship. When the cruisers reached the head of the convoy they would turn and steam along the other side, picking off surviving steamers. There would be no mercy, no pity and certainly no chivalry. These were invaders, come to do to Britain what they had done to Poland, Norway, Holland, Belgium France. No lifeboats would be lowered. Let them drown.

Before the final shell killed off the last steamer, the destroyer flotillas would be racing ahead to find the tug units."

Derek Robinson 'Invasion, 1940'

[Peter89]

What is the expected attritional results (total number of kills) that 5 RN light cruisers, 38 destroyers and 7 sloops could achieve under average expected night fighting conditions in the Channel in September 1940, assuming no German escorts at all?

"The Nore flotillas cruisers would overhaul the steamers first. British naval radar was not very clever in 1940, but it could hardly fail to pick up a crowd of such shipping. If the wind was blowing up-Channel, it might even be possible for the Salt Horses to smell the sulphurous smoke pumping out of so many funnels.

These steamers were merchant ships. There had been no time to armour them. Some carried a few machine guns or pieces of small-calibre artillery, meant for the beaches. The ships would be heavily laden with troops, tanks, artillery, horses and all the thousand stores an invading army needs, from bullets to stretchers.

The steamers were best left to the three light cruisers out of Sheerness. Each had 6-inch guns. Some had four 4-inch guns, some had eight. Their first salvoes would set ablaze enough steamers to illuminate the others. After that the ships would be sunk as fast as the crews reload.
This could not be called a battle. To defend Fleet B, the German navy only had two destroyers and some E-boats, based at Ostend. If they escorted the steamers and turned on the cruisers, they would find themselves outgunned by the bigger ships and outnumbered by twenty British destroyers.

The slaughter of the steamers would have the grim, lopsided, brutal efficiency of an abattoir. They were defenceless. They did not have the speed to scatter. Within minutes, many would be holed, listing, sinking, burning. The sea would be a tangle of barges, some cast off, some dragged down by the mother ship. When the cruisers reached the head of the convoy they would turn and steam along the other side, picking off surviving steamers. There would be no mercy, no pity and certainly no chivalry. These were invaders, come to do to Britain what they had done to Poland, Norway, Holland, Belgium France. No lifeboats would be lowered. Let them drown.

Before the final shell killed off the last steamer, the destroyer flotillas would be racing ahead to find the tug units."

Derek Robinson 'Invasion, 1940'

Haha lol. Sounds like a vivid fantasy.

[Gooner1]

Pompoms against barges?

[glenn239]

What is the expected attritional results (total number of kills) that 5 RN light cruisers, 38 destroyers and 7 sloops could achieve under average expected night fighting conditions in the Channel in September 1940, assuming no German escorts at all?

I have no idea, since that has zero to do with the point I was actually making, but if it interests you so much why don't you game it out?

You'd indicated that the addition of two German warships to the screening units would not change "the picture". What is the picture they will not change, exactly?

[Richard Anderson]

You'd indicated that the addition of two German warships to the screening units would not change "the picture". What is the picture they will not change, exactly?

"The picture" they will not change is the balance of naval forces.

Balance of Naval Forces SEELÖWE c. mid-September 1940 (British/German):

Aircraft Carriers 2/0
Battleships/Battlecruisers 5/0
Heavy Cruisers 8/0
Light Cruisers 20/3+1 training ship
Destroyers 75/9
Sloops/Torpedoboot 19/12-18
Submarines 39/19

In any case, none of the "heavy" German warships, the three light cruisers and the training ship were ever intended as "screening units" and would have been no where near the Channel convoys. They were intended to take part of a diversionary operation directed at Newcastle and Aberdeen. It is unlikely the addition of Scheer or Eugen would change that.

[glenn239]

"The picture" they will not change is the balance of naval forces.

Balance of Naval Forces SEELÖWE c. mid-September 1940 (British/German):

Aircraft Carriers 2/0
Battleships/Battlecruisers 5/0
Heavy Cruisers 8/0
Light Cruisers 20/3+1 training ship
Destroyers 75/9
Sloops/Torpedoboot 19/12-18
Submarines 39/19

In any case, none of the "heavy" German warships, the three light cruisers and the training ship were ever intended as "screening units" and would have been no where near the Channel convoys. They were intended to take part of a diversionary operation directed at Newcastle and Aberdeen. It is unlikely the addition of Scheer or Eugen would change that.

Right, but your list seems to include British carriers, battleships and heavy cruisers that were also not intended for the Channel battle while omitting the German ships not intended for operations there. I'm not certain that all of the 95 CL's and DD's on the list could enter the Channel if, for instance, Hipper was out and threatening the Western Approaches. Even less if Scheer is out as well. Taking into account the diversionary factor, and using your list, wasn't the naval balance was more like this?

Aircraft carriers 2/0
Battleships/Battlecruisers 5/1
Heavy cruisers 8/3
Light cruisers 20/4
Destroyers/Torpedoboats 75/21-27
Sloops/Siebel Ferries 19/25
Coastal artillery guns (Heavy) ?/33
Coastal artillery guns (3.9" to 6") ?/96

Bismarck and Eugen were in commission. They were on shakedown and not available for combat operations for quite some time, but I'm assuming the RN would have accounted for them in the North Sea balance.

Not sure of status of Scharnhorst, Gneisenau, and Lutzow. All were undergoing long term repairs and had sections of their crews sent to France for Sealion. None were operational, probably couldn't even sortie even in diversion. But had the RN reserved forces in case they joined the battle in the North Sea?

[glenn239]

The ones of special interest in Sealion were those with the smaller displacement, ie, 100 to 3,000 tons.

If they were of special interest, why was the average size of the 168 accumulated specifically for SEELÖWE 4,524 GRT? There may be something wrong with your assumptions.

Because the 168 ships of 4,524 were only a small fraction of the material assembled for the invasion.

Type-Number-
Cargo- 168
Barge-About 1700(?)
Tugs - 386
Motor boats - about 1,000
Mine sweepers - 86
R Boats - 45
Fishing trawlers - 64
Destroyers - 9
Torpedo boats - 18
S-boats - 24
Siebel Ferries - 25

About 3,500 total ships and boats, of which the 168 big steamers were 5% of the total. A total of maybe about 1.7 million tons of shipping? If so, the average displacement was about 480 tons. Get rid of the Motor boats (high numbers, low displacement) and maybe the average displacement of the 2,500 remaining craft was about 600 tons?

[pugsville]

The ones of special interest in Sealion were those with the smaller displacement, ie, 100 to 3,000 tons.

If they were of special interest, why was the average size of the 168 accumulated specifically for SEELÖWE 4,524 GRT? There may be something wrong with your assumptions.

Because the 168 ships of 4,524 were only a small fraction of the material assembled for the invasion.

Type-Number-
Cargo- 168
Barge-About 1700(?)
Tugs - 386
Motor boats - about 1,000
Mine sweepers - 86
R Boats - 45
Fishing trawlers - 64
Destroyers - 9
Torpedo boats - 18
S-boats - 24
Siebel Ferries - 25

About 3,500 total ships and boats, of which the 168 big steamers were 5% of the total. A total of maybe about 1.7 million tons of shipping? If so, the average displacement was about 480 tons. Get rid of the Motor boats (high numbers, low displacement) and maybe the average displacement of the 2,500 remaining craft was about 600 tons?

source for this numbers? the Minesweepers looks a little large

https://www.kbismarck.com/kriegsmarine- ... epers.html

[Richard Anderson]

Right, but your list seems to include British carriers, battleships and heavy cruisers that were also not intended for the Channel battle while omitting the German ships not intended for operations there. I'm not certain that all of the 95 CL's and DD's on the list could enter the Channel if, for instance, Hipper was out and threatening the Western Approaches. Even less if Scheer is out as well. Taking into account the diversionary factor, and using your list, wasn't the naval balance was more like this?

Hipper? After an unsuccessful Arctic cruise (25 July-9 August) she puts into Wilhelmshaven for maintenance (12 August-9 September), but while running sea trials on 30 September 1940 she suffers a major engine casualty, which puts her out of action until 28 October.

Scheer? We just covered her.

Aircraft carriers 2/0
Battleships/Battlecruisers 5/1
Heavy cruisers 8/3
Light cruisers 20/4
Destroyers/Torpedoboats 75/21-27
Sloops/Siebel Ferries 19/25
Coastal artillery guns (Heavy) ?/33
Coastal artillery guns (3.9" to 6") ?/96

Bismarck and Eugen were in commission. They were on shakedown and not available for combat operations for quite some time, but I'm assuming the RN would have accounted for them in the North Sea balance.

Bismarck and Eugen were in commission, but Bismarck did not begin her sea trials until 14 September and continued them through 5 December. From 6 December 1940 to 24 January 1941 she is at Hamburg refitting and undergoing final construction changes. Eugen we have already covered, but it is much the same. I have zero idea what your third heavy cruiser is unless you are counting Hipper, then see above.

A torpedo boat is not a destroyer...destroyers are torpedo boat destroyers after all. I cannot fathom why you think a powered barge is the same as a sloop?

Nor can I fathom why you include coastal artillery guns of any kind?

Not sure of status of Scharnhorst, Gneisenau, and Lutzow. All were undergoing long term repairs and had sections of their crews sent to France for Sealion. None were operational, probably couldn't even sortie even in diversion. But had the RN reserved forces in case they joined the battle in the North Sea?

BC Gneisenau – 20 June 1940, torpedoed by HMS Clyde, she is at Kiel under repair from 28 July to December 1940.
BC Scharnhorst – 8 June 1940, torpedoed by HMS Acasta, she is at Kiel for repairs from June to December 1940.
CA Lutzow – 11 April 1940, torpedoed by HMS Spearfish and heavily damaged, losing both props and rudder, she is in repair at Kiel and then working up until 12 June 1941 when she is again damaged, this time by a British torpedo bomber and is in repair until January 1941.

In any case, if you want to compare the "escort" for the Geleitzugen to the possible RN reaction, it is:

8 Zerstörer - 10 planned but only 8 available (I misscounted)
12-19 Torpedoboot
29 Minensuchboot M1935 - minesweepers
66 Minsensuchboot - fishing trawlers converted to minesweepers
67 Vorpostenboot - fishing trawlers converted to patrol boats
45 Räumboot - small minesweepers
20 S-Boot

Immediately available (Nore and Portsmouth Command) were:

5 light cruisers
47 destroyers
7 sloops
6 torpedo boats (five French and one Norwegian)
23 MTB

The German escorts began transferring to French ports late. Z4 was at Wilhelmshaven, while Z5, Z6, Z10, Z14, Z15, Z16, Z20 went to Brest 9 September. Earlier and they are all at Wilhelmshaven/Kiel or Norway. The rest of the "escorts" were split into four more or less similar groups, sortieing from six major ports scattered along 200 miles of coast. So the five cruisers and 38-odd DD from the Thames would first encounter Transportflotte B, then C, D, and finally E...except that E sailing from Le Havre gets to deal with the RN sailing from Portsmouth, Plymouth, and Southampton...possibly including Revenge.