Seelöwe - German & British mining operations

[taylorjohn]

Split from http://forum.axishistory.com/viewtopic.php?t=69066 by the moderator - Andreas

A good point was made by Rich at some earlier point on this thread, to the effect that the Axis simply didn't have the capability to lay the kind of minefields that the Sealion plan called for, even if it had had the mines

................

Total of all planned German minefields was about 5,600 mines. The total German stockpile of mines included roughly 4,000 EMGs, a smaller number of EMC and EMD mines (similar characteristics), and some 4,000 UMA submarine-laid anti-submarine contact mines. No fields using the latter mines were planned.

Source for the German mines: Schenck, pp.330ish.

Reading Peter Schenk's "The invasion of England 1940" the Germans did have enough vessels to lay the mines they needed - he states that all destroyers, torpedo and S boats would have been drafted into minelaying service. As the Germans planned to carry out their channel crossings at night the proposed mine barriers would have presented a real obstacle to the RN's attempts to intercept the German transport fleets.

You quote the number of 10,000 mines in the Allied mine barrier between Dover and Calais - where do you come by this figure and to what period of time does this apply?

[LWD]

...Reading Peter Schenk's "The invasion of England 1940" the Germans did have enough vessels to lay the mines they needed - he states that all destroyers, torpedo and S boats would have been drafted into minelaying service.

Just because all of these vessels were drafted does still not mean that they had enough assets. You have to figure in weather, time to lay mines, transits from the ports to the mine fields, losses, etc.

As the Germans planned to carry out their channel crossings at night the proposed mine barriers would have presented a real obstacle to the RN's attempts to intercept the German transport fleets.

That depends on where they were laid, how thick they were, whether they were swept, and if they were still in good shape when the invasion was launched. Laying the portions closer to Britain in particular are problematic as these force could be intercepted more easily and if the minefields were known swept. Indeed laying a single line of mines is non trivial unless you do it in a single pass which takes a fair amount of time.

*** edited to fix quoting ***

[taylorjohn]

...Reading Peter Schenk's "The invasion of England 1940" the Germans did have enough vessels to lay the mines they needed - he states that all destroyers, torpedo and S boats would have been drafted into minelaying service.

...Just because all of these vessels were drafted does still not mean that they had enough assets. You have to figure in weather, time to lay mines, transits from the ports to the mine fields, losses, etc.

The KM did have a detailed plan for laying the mine barriers as per above - see Schenk p333

As the Germans planned to carry out their channel crossings at night the proposed mine barriers would have presented a real obstacle to the RN's attempts to intercept the German transport fleets.

That depends on where they were laid, how thick they were, whether they were swept, and if they were still in good shape when the invasion was launched. Laying the portions closer to Britain in particular are problematic as these force scould be intercepted more easily and if the minefields were known swept. Indeed laying a single line of mines is non trivial unless you do it in a single pass which takes a fair amount of time.

But if the Germans get ashore then laying the mines closer to the coastline near to the invasion front gets easier.

The KM did not have enough resources to able to protect the mine barriers from being swept Schenk p332 - however, the LW could have provided some coverage and mine barriers can always be relaid??

[Andreas]

Split from http://forum.axishistory.com/viewtopic.php?t=69066 by the moderator - Andreas

A good point was made by Rich at some earlier point on this thread, to the effect that the Axis simply didn't have the capability to lay the kind of minefields that the Sealion plan called for, even if it had had the mines

................

Total of all planned German minefields was about 5,600 mines. The total German stockpile of mines included roughly 4,000 EMGs, a smaller number of EMC and EMD mines (similar characteristics), and some 4,000 UMA submarine-laid anti-submarine contact mines. No fields using the latter mines were planned.

Source for the German mines: Schenck, pp.330ish.

Reading Peter Schenk's "The invasion of England 1940" the Germans did have enough vessels to lay the mines they needed - he states that all destroyers, torpedo and S boats would have been drafted into minelaying service. As the Germans planned to carry out their channel crossings at night the proposed mine barriers would have presented a real obstacle to the RN's attempts to intercept the German transport fleets.

Drafted as minelayers or drafted as escorts? If the former, who was going to escort the minelayers on their sorties? leandros' quotes from Rohwer indicate that it was not the KM's view that these could be let out to play by themselves.

There is also still the question of how many mines were actually available, or have I missed the answer to it somewhere?

All the best

Andreas

[Andreas]

But if the Germans get ashore then laying the mines closer to the coastline near to the invasion front gets easier.

Let's not get into "ifs" but stick to the facts and the actual plans.

The KM did not have enough resources to able to protect the mine barriers from being swept Schenk p332 - however, the LW could have provided some coverage and mine barriers can always be relaid??

The LW could not have provided any coverage during the hours of darkness and during daytime any coverage would be completely dependent on weather conditions. Could be 100%, could be 0%.

Minesweeping could be done at night, even though it appears this was not the preferred condition, to put it mildly.

On 30 December ABINGDON was attacked by by enemy aircraft off St. Elmo and damaged one JU88. The nexxt day she was not so lucky when attacked by by two ME109s which machinegunned her causing three serious and four slight casualties. As she returned to harbour she was attacked by three more ME109s, one of which she shot down. As a result of this experience she was ordered to sweep only at night, navigating by means of a small light shown from points ashore at various fixed times so that a cross-bearing could be obtained. The strain of sweeping under these conditions must have been immense and it says much for the crew that they were able to sustain this effort for so long. On 3 January Vice Ad. Ford (VA-M) wrote to Ad. Cunningham .........

"Minesweeping is now difficult, and they appear to be laying them everywhere. Poor ABINGDON, the onl sweeper, and in daylight she got machine-gunned, eight casualties in ABINGDON alone. I`m trying to sweep during the dark hours..... until we get net defence I shall continue to be worried, escpecially for Marsamuscetto and thw submarines."
The enemy continued minelaying during December 1941 and January 1942; those laid in December appeared to be a mixture of ordinary moored and T-Type laid by E-boats and C,D and T laid by aircraft. More than a dozen exploded spontaneously in deep water and in January a T-Type was identified on the surface in Valetta Harbour and sunk.
So 1942 began with no let up. During the night of 31 January-1 February SWONA, sweeping at night, was damaged by a near miss bomb and one member of her crew was killed and 7 others injured.

See also http://www.bbc.co.uk/ww2peopleswar/stor ... 1232.shtml for a personal recollection of the D-Day sweep.

In order to relay mines, you first would have to be known that they were swept, and where. You would then have to have minelayers and mines in reserve to undertake the relaying. You would need time to relay. Was all of this factored into the German naval plan?

All the best

Andreas

[RichTO90]

Split from http://forum.axishistory.com/viewtopic.php?t=69066 by the moderator - Andreas

A good point was made by Rich at some earlier point on this thread, to the effect that the Axis simply didn't have the capability to lay the kind of minefields that the Sealion plan called for, even if it had had the mines

................

Total of all planned German minefields was about 5,600 mines. The total German stockpile of mines included roughly 4,000 EMGs, a smaller number of EMC and EMD mines (similar characteristics), and some 4,000 UMA submarine-laid anti-submarine contact mines. No fields using the latter mines were planned.

Source for the German mines: Schenck, pp.330ish.

Reading Peter Schenk's "The invasion of England 1940" the Germans did have enough vessels to lay the mines they needed - he states that all destroyers, torpedo and S boats would have been drafted into minelaying service. As the Germans planned to carry out their channel crossings at night the proposed mine barriers would have presented a real obstacle to the RN's attempts to intercept the German transport fleets.

Drafted as minelayers or drafted as escorts? If the former, who was going to escort the minelayers on their sorties? leandros' quotes from Rohwer indicate that it was not the KM's view that these could be let out to play by themselves.

There is also still the question of how many mines were actually available, or have I missed the answer to it somewhere?

All the best

Andreas

Well, they laid perhaps as many as 4,500 in August (although I suspect it was probably fewer than 3,000) and considerably fewer in September, but were planning for 5,600 in the Seelöwe fields. We have seen figures of 12,000 'mines' available circa May I think it was? And 4,000 EMG and 'smaller' numbers of similar types ready for the barriers in September. So I think they may have had sufficient for the 5,600, barely. But that still is only a linear, single-row density of about 20 per kilometer for the planned barriers, or 1 per 50 meters. Now if they did the 'multiple' rows the Germans plans called for, which of course is standard practice, then two rows means 1 per 100 meters and three rows means 1 per 150 meters, although of course the rows would be staggered. Compare that to the roughly 8,500 laid by the French and British in three rows to 'close' the Dover strait, about 2,800 per row with each row about 40 kilometers in length, so 70 per kilometer and thus about 14 meter intervals? Which was sufficient to sink IIRC four U-Boote and thus make Dönitz order his skippers to use the longer route north into the Atlantic (if France hadn't fallen that alone could have put a crimp into his campaign and probably would have forced the production of more Typ-IX to get longer endurance).

So the problems are manifold:

1. Were there enough mines to meet the requirements of the plan?
2. Was there enough minelaying capacity to get the mines laid within the time constraints of the plan?
3. Were there sufficient escorts available to screen the minelayers and to simultaneously augment the minelaying capacity (otherwise (2) seems to be an impossibility).
4. Were the planned fields dense enough to deter and attrit the possible reaction of the Royal Navy enough that they could not interfere with the landings or so as to render their reaction ineffective?
5. Were the mines to be employed sophisticated enough to prevent them being easily swept by the standard mineclearing methods?

And I think the answers are:
1. Maybe.
2. Probably not, unless conditions were absolutely perfect for five days out of seven.
3. No.
4. No.
5. No.

[taylorjohn]

Andreas, it is not an 'If'' - if the Germans control both coastlines along the Straits of Dover laying mines over that area is going to be easier.

I agree that Luftwaffe coverage during the day depends on the weather, but attempting to mine sweep over hostile waters at night in 1940 would be very difficult (also, I imagine, quite dangerous!)

Schenk doesn't specifically mention relaying mine barriers but (and this is a guess) aerial reconnaissance by the Luftwaffe and surveillance by the KM's u-boats/patrol ships of the RN's movements would give the Germans an idea as to whether their mine barriers were holding up.

According to Schenk, there were more than enough mines for the proposed mine barriers and these included EMC and EMD moored mines, UMA anti-sub mines, plus mines airdropped by the 9th Fliegerdivision.

Again according to Schenk there was enough mine laying capacity (including torpedo boats, destroyers etc) to get the mines laid within the time constraints of the plan.

Not sure about sufficient escorts available to screen the minelayers but is there any evidence that the British were successful at disrupting the KM's mine laying activities in 1940.

Regards the effectiveness of the mine barriers Schenk points out that 2 RN destroyers were sunk and 1 was severely damaged during anti-invasion mine laying operations in Autumn 1940!!

Schenks book 'Invasion of England 1940' covers the above in quite some detail see pp328-333.

[Andreas]

Andreas, it is not an 'If'' - if the Germans control both coastlines along the Straits of Dover laying mines over that area is going to be easier.

And if they had taken London immediately it would have been even less of a problem. The "If" that has no place here is the assumption that they take control of the other side of the channel. If you want to base any argument on that assumption, kindly take it to the What-If section of the forum, there is a thread open for it.

I agree that Luftwaffe coverage during the day depends on the weather, but attempting to mine sweep over hostile waters at night in 1940 would be very difficult (also, I imagine, quite dangerous!)

Why? More specifically, why are the waters in mid-channel suddenly 'hostile' at night to the RN? I would think it would be quite difficult, not to say dangerous, to lay mines in hostile waters at night. Unless you assume that all shipping channels up to the British coast were controlled by the Germans in 1940, by day and night. That would be news to me.

Schenk doesn't specifically mention relaying mine barriers but (and this is a guess) aerial reconnaissance by the Luftwaffe and surveillance by the KM's u-boats/patrol ships of the RN's movements would give the Germans an idea as to whether their mine barriers were holding up.

What were the arrangements for covering the minefields then? Would not the same ships that are supposed to cover the mine fields (e.g. Vorpostenboote) be busy preparing for the invasion, where they have escort and transport duties?

According to Schenk, there were more than enough mines for the proposed mine barriers and these included EMC and EMD moored mines, UMA anti-sub mines, plus mines airdropped by the 9th Fliegerdivision.

I very seriously doubt that any air-dropped mines would have been part of the mine lanes. They would have been used to mine harbour entrances and likely approach routes far away from the channel, due to precision issues.

Again according to Schenk there was enough mine laying capacity (including torpedo boats, destroyers etc) to get the mines laid within the time constraints of the plan.

Assuming good weather throughout?

Not sure about sufficient escorts available to screen the minelayers but is there any evidence that the British were successful at disrupting the KM's mine laying activities in 1940.

That is a non-argument. They did not try to lay mines close to the English shores either. Whether the RN would have interfered had they tried to do so is an open question.

Regards the effectiveness of the mine barriers Schenk points out that 2 RN destroyers were sunk and 1 was severely damaged during anti-invasion mine laying operations in Autumn 1940!!

If that is indeed what Schenk points out, it appears he is talking nonsense, and it would make me doubt his qualification to talk on the subject of mining, unless the British managed to lose two and damage one twice in 1940. The three destroyers I know off ran on a German offensive minefield off Texel on 1 September, during summer. The minefield had been laid on 7/8 August. It was not anti-invasion anything. That mines can damage and sink ships is also not a point of contention here, that's what they were there for. Unless you can show that SW1 had similar mine densities to those barriers planned for the invasion, I fail to see the relevance.

31.8./1.9.1940
Nordsee
Die 20. brit. Zerstörerflottille läuft mit Ivanhoe, Intrepid, Icarus, Esk und Express aus, um nordwest. von Texel die Minensperre CBX.5 auszubringen. Nach Luftaufklärundsmeldungen werden die Zerstörer Jupiter (Capt. Lord Louis Mountbatten), Jackal, Kelvin und Vortigern zur Verstärkung befohlen. Bei dem Versuch, deutsche Schiffe abzufangen, läuft Express auf eine Mine der kürzlich ausgelegten dt. Sperre »SW 1« (siehe 7./8.8.), anschließend auch die zur Hilfe eilenden Esk und Ivanhoe. Die Esk sinkt. Während Vortigern am Ausgang D der brit. Minenfelder wartet, suchen Jupiter und Kelvin nach den zwei beschädigten Zerstörern. Kelvin nimmt Express bis zum Eintreffen von Schleppern an den Haken. Der Zerstörer Garth findet die Ivanhoe, die zusätzlich von einem dt. Wasserflugzeug angegriffen und beschädigt wird. Da Abschleppversuche der beschädigten Ivanhoe zu gefährlich sind, versenkt Kelvin den Zerstörer mit einem Torpedo.

Schenks book 'Invasion of England 1940' covers the above in quite some detail see pp328-333.

I see.

All the best

Andreas

[taylorjohn]

The "If" that has no place here is the assumption that they take control of the other side of the channel. If you want to base any argument on that assumption, kindly take it to the What-If section of the forum, there is a thread open for it.

I would be grateful if you could provide me with a link to that thread as I cannot find it – thanks John

I agree that Luftwaffe coverage during the day depends on the weather, but attempting to mine sweep over hostile waters at night in 1940 would be very difficult (also, I imagine, quite dangerous!)

Why? More specifically, why are the waters in mid-channel suddenly 'hostile' at night to the RN? I would think it would be quite difficult, not to say dangerous, to lay mines in hostile waters at night. Unless you assume that all shipping channels up to the British coast were controlled by the Germans in 1940, by day and night. That would be news to me.

I think you misunderstand me - I meant that sweeping mines in the dark where there are potentially enemy ships nearby would, I imagine, be quite difficult.

Schenk doesn't specifically mention relaying mine barriers but (and this is a guess) aerial reconnaissance by the Luftwaffe and surveillance by the KM's u-boats/patrol ships of the RN's movements would give the Germans an idea as to whether their mine barriers were holding up.

What were the arrangements for covering the minefields then? Would not the same ships that are supposed to cover the mine fields (e.g. Vorpostenboote) be busy preparing for the invasion, where they have escort and transport duties?

The KM did not have sufficient resources to consider covering the mine barriers on a permanent basis.

According to Schenk, there were more than enough mines for the proposed mine barriers and these included EMC and EMD moored mines, UMA anti-sub mines, plus mines airdropped by the 9th Fliegerdivision.

I very seriously doubt that any air-dropped mines would have been part of the mine lanes. They would have been used to mine harbour entrances and likely approach routes far away from the channel, due to precision issues.

Yes, according to Schenk the mines to be airdropped by the 9th Fliegerdivision were intended to block the naval base at Portsmouth,

Again according to Schenk there was enough mine laying capacity (including torpedo boats, destroyers etc) to get the mines laid within the time constraints of the plan.

Assuming good weather throughout?

Or at least reasonable weather.

Regards the effectiveness of the mine barriers Schenk points out that 2 RN destroyers were sunk and 1 was severely damaged during anti-invasion mine laying operations in Autumn 1940!!

If that is indeed what Schenk points out, it appears he is talking nonsense, and it would make me doubt his qualification to talk on the subject of mining, unless the British managed to lose two and damage one twice in 1940. The three destroyers I know off ran on a German offensive minefield off Texel on 1 September, during summer. The minefield had been laid on 7/8 August. It was not anti-invasion anything. That mines can damage and sink ships is also not a point of contention here, that's what they were there for. Unless you can show that SW1 had similar mine densities to those barriers planned for the invasion, I fail to see the relevance.

Mine barrier SW1 although not directly relevant to the German invasion was considered during the planning of Sealion - my point was simply that the mine barriers could potentially have been a formidable obstacle to the RN's attempt to intercept the KM's transports - the densities of the mine barriers varied!

[LWD]

Andreas, it is not an 'If'' - if the Germans control both coastlines along the Straits of Dover laying mines over that area is going to be easier.

Except the German mine layers and their escorts had multiple duties during Sea Lion. Indeed they had some of the more dangerous tasks so you can't assume that the resources they had prior to the start of the invasion are what they would have after it started. These ships could be sunk, damaged, or tasked to other duties.

I agree that Luftwaffe coverage during the day depends on the weather, but attempting to mine sweep over hostile waters at night in 1940 would be very difficult (also, I imagine, quite dangerous!)

Would they be hostile though. Or just disputed? If the RN is sweeping it's probably to support an RN raid on German shipping and doesn't have to be extensive and the raiding force can also provide the escrot.

Schenk doesn't specifically mention relaying mine barriers but (and this is a guess) aerial reconnaissance by the Luftwaffe and surveillance by the KM's u-boats/patrol ships of the RN's movements would give the Germans an idea as to whether their mine barriers were holding up.

The mine barriers were thin enough that the surveillance of RN vessels would not necessarily indicate any change in status of the mine fields. Did they have the mines to relay the fields? Relaying fields can also be very tricky given the lack of GPS. Finding the end of a hole by hitting a mine is far from ideal.

...
Again according to Schenk there was enough mine laying capacity (including torpedo boats, destroyers etc) to get the mines laid within the time constraints of the plan.....

Sufficient theoretical capacity doesn't mean sufficient real capacity. I've posted a quote from a document that Andreas originally supplied that stated the KM was behind on the required mine sweeping (in September I believe) not due to lack of resources but due to lack of LW air support. So while there may be enough vessels on the list to lay the mines in the time frame weather, enemy action, and other task can shift the balance against that.

[LWD]

I found a document on German mines that may be of interest in regards to this topic:
http://www.lexpev.nl/downloads/germanun ... es1946.pdf
It does cover the entire war so one must be careful when trying to apply it directly to Sealion.
And here's one on British mining operations:
http://www.naval-history.net/xGM-Ops-Minelaying.htm

[Juha Tompuri]

A reply to http://forum.axishistory.com/viewtopic. ... 0#p1779212

.. I knew the threads (the other having John T as a voice of sanity there), that's why I asked whether there was any Naval related sources to back up the claim of "quick minefield deterioration" ?

The source in that thread is a photocopy of a book that is quoteing a German general I believe. If it's not explicit it's certainly implied that the information comes from the KM.

As General Blumentritt was not a Naval officer and no other sources than his have by so far being presented, your reply is not based on facts, but speculation.

Yes, but the text (and the understanding) comes from a non-navy person, and nothing by so far presented fact backs up his claims.

So indeed there is an element of speculation on it being based on naval sources but said speculation is based pretty soundly on fact and logic.

As above.

it's not clear just what percentage one expects to break away in that period. Is it 10% or 50% or ???? However if one looks at the mines available and the size of the fields they were pretty thin already so any deteriation could be pretty significant.

Sourceless speculation.

???? It's clearly not speculation. I was simply pointing out that we have no idea what percentage of the mines would break their cables in the period indicated. Since some WWII minefields lasted well after the war it clearly wasn't 100%. In the context it seems implies that periodic reseeding of the fields would be necessary. Furthermore it's not clear if that number was a general rule of thumb or applied specifially to the conditions in the channel. This isn't speculation is recognizing the limits of the information presented.

Do you believe in the speculation that it would be possible that up to/more than 50% of the mines laid would have been torn loose at the time frame mentioned?

It's certainly not as good of data as I would like but at this point it is all we have. If you have more one way or another please present it.

I really haven't seen any facts that backs up the claim that Channel and the neighbouring waters were full of floating mines every now and then during the war.

Regards, Juha

[Juha Tompuri]

One could argue it is speculation that Blumentritt was clueless about the question of naval mining operations just because he was an army officer. He was on the staff planning the operation.

http://forum.axishistory.com/viewtopic. ... 0#p1779213
No one (before) here has claimed General Blumentritt being clueless.


Regards, Juha

[Juha Tompuri]

From http://forum.axishistory.com/viewtopic. ... 0#p1779209

in Blumentritt's own words...

"Sufficient sea mines were not available to form a barrier, and every 8 to 14 days would break away from their moorings and have to be replaced. Our naval advisers were Admirals Cyliax and Salwacht."

http://forum.axishistory.com/viewtopic.php?t=121586

In reality, that is not what Blumentritt is mentioned to have written(?)

Nor he had written that "some mines would break away from their moorings" or "part of the mines (at the minefield) would break away from their moorings"
But he wrote that "and every 8 to 14 days the mines would break away from their moorings and have to be replaced. Our naval advisers were Admirals Cyliax and Salwächt(er?)."

Regards, Juha

[Urmel]

One could argue it is speculation that Blumentritt was clueless about the question of naval mining operations just because he was an army officer. He was on the staff planning the operation.

http://forum.axishistory.com/viewtopic. ... 0#p1779213
No one (before) here has claimed General Blumentritt being clueless.


Regards, Juha

You're the one who says basing a statement on naval matters on him is pure speculation because he's not a naval officer, not me. Shrug.

I don't really see how the question of minefield deterioration matters. If the Germans still need the minefields after 8 days they have a whole world of other problems.

The best way of figuring out whether there was anything real to this question would presumably be to look at British mining operations to block the channel to submarines - was re-seeding on a bi-weekly/monthly/whatever basis needed to keep them intact? I doubt it, but I don't know.