Holland Shadows Bismarck Instead

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minoru genda
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Re: Holland Shadows Bismarck Instead

Postby minoru genda » Mon Dec 08, 2008 1:35 am

Hello tnemelckram, I read your scenario and I think Hood and POW would be able to shadow Bismarck and PE but I have my doubts about the approach of Tovey's force. I'm not sure if KGV and Repulse can intercept Bismarck if she isn't slowed first. Maybe I'm wrong but I've looked at some charts and it seems to me that as long as Bismarck keeps going south Tovey could never intercept with his battleships, he is too far behind I think. So it could be just a matter of time until Hood and POW run out of fuel and forced to break the pursuit because Tovey might never arrive. What do you think?
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Re: Holland Shadows Bismarck Instead

Postby dunmunro » Mon Dec 08, 2008 2:51 am

minoru genda wrote:Hello tnemelckram, I read your scenario and I think Hood and POW would be able to shadow Bismarck and PE but I have my doubts about the approach of Tovey's force. I'm not sure if KGV and Repulse can intercept Bismarck if she isn't slowed first. Maybe I'm wrong but I've looked at some charts and it seems to me that as long as Bismarck keeps going south Tovey could never intercept with his battleships, he is too far behind I think. So it could be just a matter of time until Hood and POW run out of fuel and forced to break the pursuit because Tovey might never arrive. What do you think?

This is true. Holland had to slow or stop Bismarck in the DS.

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Re: Holland Shadows Bismarck Instead

Postby tnemelckram » Sun Dec 14, 2008 12:02 pm

Hi All! I started this thread asking whether it would have been a sound plan for Holland to shadow Bismarck with Hood, PoW, Suffolk, Norfolk and his destroyers for 24 hours instead of engaging at Denmark Straits, leading Tovey's force to her and engaging her with an overwhelming advantage of four capital ships to one. I appreciate all of the responses.

In this post: viewtopic.php?f=1&t=1810&st=0&sk=t&sd=a#p20853
I concluded that I don't think that my alternate scenario merit. It would be a radical departure from the traditions and doctrines of the Royal Navy that dictated immediate and aggressive action. It
would come under intense scrutiny if it failed. Holland and Tovey better have damn good reasons to justify it. Those reasons can only be based on things they knew or had high confidence in before the time of the Denmark Straits battle.

A. How Bismarck's Speed Affects My Scenario

I conclude that at that time they believed that Bismarck had at least a two knot speed advantage on Holland's capital ships. Thus, among other things, Holland and Tovey had no choice but to assume that it could outrun radar or other shadowing when making their plan. This belief and assumptionshows up in Tovey's after action report, where he writes this:

29.
. . . . . . .

From my point of view the greatest danger lay in his bugging the coast of
Greenland, and then making his way to the westward, where I suspected
he might have an oiler: for, if he could refuel, he would be able to use
higher speeds than the King George V could maintain
and so get away.

30. The enemy's alteration to the southward and his reduction speed were
a great relief
, although there seemed a good chance that he was leading
our forces into a concentration of U-Boats. It suggested that he did not know
of my force and it made interception possible.

31. There was still a grave risk of his getting away by sheer speed,

http://hmshood.com/hoodtoday/2001expedition/index.htm (emphasis added)

After my above post there has been a great deal of discussion of what Bismarck's speed actually was. I respectfully suggest that this misses the point of the thread. What matters is what Tovey and Holland believed her speed to be relative to their own capital ships before they made a choice between shadowing or engaging at Denmark Straits. At (or after, if you prefer) the relevant time, Tovey believes that Bismarck higher speed than KGV and could get away. It follows that Tovey believed that speed was also higher than KGV's sister PoW, and since the latter was operationally tied to Hood, as a practical matter faster than the speed at which Hood could shadow. No other assumption would have been defensible for the limited purposes of my alternate scenario.

B. U Boat Threat

I also assume in my alternate scenario that the British had good reason to believe that Holland's shadowing force would not be lead into a U-Boat trap within the next 24 hours. Tovey mentions his concern that Bismarck would lead his force into such a trap and his relief because Bismarck's lower speed suggests that she was not aware of his force. I think that Tovey and Holland knew enough to conclude that this risk was minimal and acceptable; they could intercept most if not all German naval transmissions, that the Germans knew that, and that the same was true in reverse. Without being able to decode and read them, they could rely on detecting changes in their pattern, timing or nature. A sudden increase in short and similar transmissions at regular intervals, each repeated several times, which pattern continues for many hours and begins after the shadowing started, would indicate a possible U-Boat trap.

a. The transmissions would have to start suddenly because there would be no reason to make
them until the shadowing started.

b. The transmissions would have to increase and be at regular intervals. The U Boats need the
British course and speed to intercept. This requires the Bismarck to begin numerous
transmissions to provide the necessary data.

c. Each transmission would have to be repeated several times. The goal is to place a number
of U Boats, single or in a group, somewhere along the British track. Repeated transmissions
would maximize the number of U Boats that hear them - an obvious prerequisite to acting
act on them.

d. Tying together b. and c. above, each U Boat might not hear each transmission, so you have
to make enough to ensure that any of the the U Boats can miss some of them and still have
enough information to determine course and speed.

e. The transmissions would have to be short assuming that Bismarck would only
communicate the essential information - which is course and speed.

f. The transmissions would have to be similar if they only contain that essential information. In
this case the British could tell if they were similar for their purposes even if encoded. They
would have a sequence to compare, which would reveal a substitution pattern in the symbols
or characters used to convey the coded information. The duration and/or number of
characters or symbols would be the same. This suggests that each coded transmission
conveys the same type of information and has the same purpose.

g. The new transmission pattern would have to continue for a number of hours before even
a single U Boat could be in position to attack. Holland and Tovey knew that just about all of
Bismarck's operations would be at undetermined places in shipping lanes, that all U
Boats not dedicated to support the Rhine Operation would also be in shipping lanes, and that
U Boats are relatively slow. They could expect that the prepositions of the dedicated U
Boats would be where Bismarck would spend the most time and would be scattered because
the places where she might need support could not be foreseen. Thus there would be
ample time to react.

h. The threat from a single U Boat is minimized by the six destroyers in Holland's force, so
Tovey and Holland could regard the German's well-demonstrated skill at group attacks as the
real U Boat threat to the shadowers. Bismarck's course and speed transmissions alone
would not be enough to gather several U Boats in the right place at the right time, each
knowing what they will do and what the others will do. A new series of transmissions is
required; either among the U Boats or one-way directions from land. I think that if the
British planned beforehand to look for such a second new pattern shortly after the first new
pattern from Bismarck, they could count on intercepting enough of it to confirm that
the Germans were developing a multiple U Boat trap for the shadowers.

Considering all of this, in particular g. above, I think it was sloppy for me to say that the British knew beforehand that their shadowers would be safe from U Boat traps for 24 hours. Instead, if the amount of time beginning of Holland's shadowing and ending with Tovey's interception was less than that required for a U Boat to move from the nearest shipping lane to the interception point, the British had a sound basis for the conclusion that there was no significant U Boat threat to the shadowers.

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Re: Holland Shadows Bismarck Instead

Postby Vic Dale » Sun Dec 14, 2008 1:49 pm

There would be no need for any transmissions of enemy course and speed, because Lutjens would know well in advance the enemy's position at a given time. He would be leading them there. Just one transmission to Group West would be enough to secure the agreement from Doenitz that a trap consisiting of five or six U-Boats, should be laid in such and such a grid-square, in so many hours time and Lutjens could draw the enemy into it.

Routine transmissions on the U-Boat net would inform each boat of the Fleet Commander's wishes. Boats surfaced at night to recharge batteries and make their reports, so an instruction to make a certain sqaure on the chart could be targetted to each boat without need for many repeats of the transmission. All would appear as normal U-Boat traffic.

At 2115 on the 26th, Group West broadcast; "Emergency all U-Boats with torpedoes to proceed at once and at full speed towards Bismarck grid square BE29." This is just after the torpedo attack which disabled Bismarck's rudders. U557 received this call to arms at 0635 on the 27th and presumably it was a relay from the duty RT boat, or relay station as group West would have been aware that little could now be done and the request for a U-Boat to save the war diary had already been made. Such a signal would be a short signal with the necessary information broken down into the U-Boat code before encrypting into enigma code for final transmission. That is the only instruction regarding defence of the flagship which was addressed to U557, so presumably the U-Boats would work out their own attack plan as as their GHG picked up the approaching ships.

I am wondering if it was possible for Bismarck to transmit a sonic beacon for the waiting U-Boats.

The fact that Bismarck slowed to 16 knots at times, may well have been part of the plan to get the British used to such changes and also for Lutjens to learn just how his shadowers deployed on these occassions. This could also be transmitted along with routine reports to Group West, where the planners could work out elements of an attack profile for the waiting U-Boats. The rest would be up to the individual boats using their GHG hydrophones whilst forming the teeth of the trap.

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Re: Holland Shadows Bismarck Instead

Postby Bgile » Sun Dec 14, 2008 3:02 pm

The U-boat screen could be positioned before Bismarck sails from Norway. Then Bismarck leads any resulting pursuers through it.

Since Bismarck didn't have active sonar, a "sonic beacon" wasn't possible.

If she did, it would be a wonderful way to help the British track her.

Tovey's destroyers would be useless at antisubmarine work at any speed greater than 15 kts and more likely 10 kts. They would also run out of fuel so fast that they would only be able to stay with Tovey's large ships for a day or two at 25 kts.

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Re: Holland Shadows Bismarck Instead

Postby Dave Saxton » Sun Dec 14, 2008 4:32 pm

Bismarck did have active sonar in addition to GHG. The active Sonar was called the S-Gaerate.
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Re: Holland Shadows Bismarck Instead

Postby Vic Dale » Sun Dec 14, 2008 5:11 pm

Bgile wrote:The U-boat screen could be positioned before Bismarck sails from Norway. Then Bismarck leads any resulting pursuers through it.

Since Bismarck didn't have active sonar, a "sonic beacon" wasn't possible.

If she did, it would be a wonderful way to help the British track her.

Tovey's destroyers would be useless at antisubmarine work at any speed greater than 15 kts and more likely 10 kts. They would also run out of fuel so fast that they would only be able to stay with Tovey's large ships for a day or two at 25 kts.



There would be no point positioning a U-Boat screen prior to the development of the tactical situation. That would only reveal itself as the British responded to the break out and it would disrupt the U-Boat campaign itself to have U-Boats drawn from other duties on the off chance. Once the ships were in the Atlantic it would be a different matter especially if being continually shadowed. If the squadron got into the Atlantic un-noticed there would be nothing to draw into the trap.

"S-Gerate then. I didn't know about that.

The use of a sonar beacon would be a local tactical ploy to alert lurking U-Boats to the fact that the ship which might be looming large in their attack-periscopes was the flagship. This would permit her to pass unmolested whilst "open Season" could be declared on all other vessels. Additionally an intermittent "squawk" on the beacon would help to concentrate U-Boats ahead of Bismarck ready for the attack.

Tovey's destroyer screen would be rotating for bunkering as a matter of routine. The only thing which might stop them would be the weather, which if extreme would not stop the battleships, but would surely cause structural damage to these lighter vessels if they maintained high speed. U-Boats could rarely make more than 7 knots when submerged and if the destroyers got in amongst a pack waiting for the Home Fleet, the U-Boats would be forced down and lose the ability to redeploy at their surface speed of 17 knots, useful in the event of a change in the tactical situation. The mere presence of destroyers in daylight could nullify the effectiveness of a U-Boat concentration aimed at the Home Fleet.

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Re: Holland Shadows Bismarck Instead

Postby Bgile » Sun Dec 14, 2008 5:30 pm

Dave Saxton wrote:Bismarck did have active sonar in addition to GHG. The active Sonar was called the S-Gaerate.


Oops! Hoist by me own petard!

I still stand by the fact that running around transmitting would be very convenient to the British.

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Re: Holland Shadows Bismarck Instead

Postby Bgile » Sun Dec 14, 2008 5:42 pm

Vic Dale wrote:Tovey's destroyer screen would be rotating for bunkering as a matter of routine. The only thing which might stop them would be the weather, which if extreme would not stop the battleships, but would surely cause structural damage to these lighter vessels if they maintained high speed. U-Boats could rarely make more than 7 knots when submerged and if the destroyers got in amongst a pack waiting for the Home Fleet, the U-Boats would be forced down and lose the ability to redeploy at their surface speed of 17 knots, useful in the event of a change in the tactical situation. The mere presence of destroyers in daylight could nullify the effectiveness of a U-Boat concentration aimed at the Home Fleet.

I'm sorry ... I wasn't aware of this rotation you speak of. Where was it based? How many destroyers were involved, and how fast did they have to go and for how long in order to rendezvous with heavy ships going 25 kts or more? Oddly enough, the US fleet doesn't seem to have been capable of doing this. They had to slow to 12 - 15 kts periodically to refuel from larger ships, but of course in 1941 the RN really couldn't do even that with the same efficiency.

You must tell us more about this rotation. It would appear to me that the destroyers involved would have had to have economical speeds of 60 kts or so to make this practical if they had to refuel in port.

How are the destroyers going to "get in amongst a pack" if they don't know where it is?

Having personally operated among high speed destroyers during daylight, in my opinion you are greatly overestimating their capability.

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Re: Holland Shadows Bismarck Instead

Postby Vic Dale » Mon Dec 15, 2008 7:11 pm

Bgile wrote:
Vic Dale wrote:Tovey's destroyer screen would be rotating for bunkering as a matter of routine. The only thing which might stop them would be the weather, which if extreme would not stop the battleships, but would surely cause structural damage to these lighter vessels if they maintained high speed. U-Boats could rarely make more than 7 knots when submerged and if the destroyers got in amongst a pack waiting for the Home Fleet, the U-Boats would be forced down and lose the ability to redeploy at their surface speed of 17 knots, useful in the event of a change in the tactical situation. The mere presence of destroyers in daylight could nullify the effectiveness of a U-Boat concentration aimed at the Home Fleet.

I'm sorry ... I wasn't aware of this rotation you speak of. Where was it based? How many destroyers were involved, and how fast did they have to go and for how long in order to rendezvous with heavy ships going 25 kts or more? Oddly enough, the US fleet doesn't seem to have been capable of doing this. They had to slow to 12 - 15 kts periodically to refuel from larger ships, but of course in 1941 the RN really couldn't do even that with the same efficiency.

You must tell us more about this rotation. It would appear to me that the destroyers involved would have had to have economical speeds of 60 kts or so to make this practical if they had to refuel in port.

How are the destroyers going to "get in amongst a pack" if they don't know where it is?

Having personally operated among high speed destroyers during daylight, in my opinion you are greatly overestimating their capability.


It is a matter of fact that the ships of any squadron in the Royal Navy were bunkered at different times and this itself would ensure staggered oiling rotation. The battle squadron would not be left bare so the scort could oil.

When the Germans sent raiding squadrons to sea, they could begin with practically full tanks so as to maximise a squadron's range, and this might be done on occassions for special operations in the RN, but mostly the RN had to scrape units together which were already operating at sea.

The RN did not adopt refuelling at sea until quite late due to the many oiling stations available and within reasonable steaming distance, it may have been possible to oil from heavy units but a battle squadron chasing a German raider would not stop to oil destroyers. They would be detached in ones and twos, so that the escort remained intact.

My reference to the impact on U-Boats by a squadron of destroyers clearly contained the words "could" and "if". I know full well that different U-Boat captains responded in different ways tactical situations, but if you are telling me that you operated in a hostile situation on the surface among fast enemy destroyers in daylight, then your navy differs from my own.

Tovey's destroyers would have to be sweeping ahead of the battle squadron which they probably were and on sighting any U-Boat would lay heavy, rapid and accurate fire on it forcing it down. If the U-Boat commander had a death wish he could of course remain on the surface.

The sweep of the destroyer screen would be such that it covered a wide area ahead of the battle squadron to include the maximum range and best firing angles for effective torpedo patterns. We had submarines as well as the Germans so the tactical maths would be known in advance. The U-Boats would not know the exact course of the battle squadron as it would be many miles astern of Bismarck and having allowed their flagship to pass would use their time on the surface to good effect getting into position. Further adjustment would be needed as the squadron approached and for that they would need to be on the surface, submerging and remaining at periscope depth as the first mastheads appeared. These of course would be the destroyers, whose lookouts would be watching intently for scope-feathers on the sea. The U-boats would not know on which side of the screen the battle squaron was deployed so the best attacking position would be very hard to acheive.

Now, instead of a convoy making barely 8 knots, they have a battle squadron making 28 to 29 knots so the time allowed for assessing angle of approach and deflection is very short and each "look" is fraught with danger. They not only have to look for the target, but also take account of the destroyers. If a boat is spotted (and she will not know until she is attacked) she will have to dive or risk destruction. The chances of a successful interception and attack are being cut down to a very low order of probability. If the weather is such that it will hamper the destroyers it will also impact on the U-boats.

In actuality, the best course for the U-boats might lie not so much in attack as advertising their presence, forcing the enemy to zig-zag, thus loosing time on the chase.

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Re: Holland Shadows Bismarck Instead

Postby Bgile » Mon Dec 15, 2008 8:52 pm

Vic,

I think if you would just try to plot distance and speed of this relay of destroyers you are talking about, you would see that it's just not possible. For example, Holland's four destroyers had to be sent to Iceland to refuel and had no destroyers from that point on. You would find that any unit forced to maintain high speed for an extended period will lose it's destroyers after a few days. The speed involved makes it nearly impossible to rendezvous with more destroyers without losing contact with the ship you are trying to shadow.

At least one British heavy ship passed withing easy torpedo range of a u-boat, but she was out of torpedoes.

I don't dispute that u-boats would be forced to dive to keep from getting attacked by screening destroyers. I was suggesting a barrier patrol with Bismarck leading her pursuers though it. You dismissed that with a generic comment about tactical situation. The fact is, the PoW follows Bismarck wherever she wants to lead. I'm not talking about Newfoundland, here.

Actually I still don't understand why the Germans didn't put a u-boat screen in a position to attack Norfolk and Suffolk when they shadowed Bismarck.

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Re: Holland Shadows Bismarck Instead

Postby tommy303 » Mon Dec 15, 2008 9:23 pm

I believe most of the Uboats in that area of the Atlantic were stationed south of Greenland along the convoy route and none were close enough to get to the Denmark Straits in time to be of any use to Luetjens before he would be out and into the Atlantic. With storm conditions the boats would probably be restricted 10 knots and would not have the speed to come to Luetjens. It made more sense for the squadron to come to them.

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Re: Holland Shadows Bismarck Instead

Postby Bgile » Mon Dec 15, 2008 9:47 pm

tommy303 wrote:I believe most of the Uboats in that area of the Atlantic were stationed south of Greenland along the convoy route and none were close enough to get to the Denmark Straits in time to be of any use to Luetjens before he would be out and into the Atlantic. With storm conditions the boats would probably be restricted 10 knots and would not have the speed to come to Luetjens. It made more sense for the squadron to come to them.


I agree, but couldn't they have prepositioned there before the operation started? The British were bound to put cruisers there.

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Re: Holland Shadows Bismarck Instead

Postby tommy303 » Tue Dec 16, 2008 3:10 am

Yes, SKL through BdU could have positioned some Uboats in the Denmark Straits, but would also have had to do the same with the Iceland Faroes passage as well. The latter was the one actually favored by SKL assuming a breakout went undetected. The problem was BdU had a relatively small number of boats in the Atlantic at the time due to refit and repair routines, and although the orders for Operation Rhein allowed the Chief of Fleet on Bismarck to exercise his authority and call for a redeployment, there was little reason in the planning stage and the initial stage of the mission to do so. Past experience with raids by Hipper, Scheer, and Scharnhorst & Gneisenau did not provide any evidence that the Royal Navy was deploying advanced sea search radars on ships. This was the real monkey wrench in the German plans, as it was assumed that Lütjens could probably evade enemy cruisers by using the bad weather front moving through the waters around Iceland. It was not until Lütjens actually encountered Suffolk that the Gemans realized this assumption was out dated. It might have been probable, that, had the SKL known of British marine radar developments, U-boats might have been assigned to scout the passages open to Lütjens and perhaps attacked any cruisers spotted.

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Re: Holland Shadows Bismarck Instead

Postby RF » Thu Jan 08, 2009 2:42 pm

Reading the posts within this thread does remind of the question that Ihave posed before - just how many Allied warships does it take to dispose of the Bismarck?

If Holland is reduced to shadowing then almost any configuration or concentration should be achievable, providing, as pointed out above, the Germans don't break off the shadowing pursuers. By cutting off the escape routes to Norway and France the British could eventually force the German ships to slow down to conserve fuel and eventually pick them off.

Of course with a shadowing operation another option would be available to Holland, if he decided against waiting for Tovey - split his ships on to either flank of Bismarck and attacking so that Bismarck is forced to divide its fire. Logically it would have been prudent to await the arrival of KGV to achieve this, and perhaps even better to keep Hood out of the action until it was heavily engaged against the other British ships and its gunnery degraded by battle damage.
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