Battle of Atlantic

[Chris Allen]

I saw a video recently that challenged what I thought was "accepted
truth" about the battle of the Atlantic.
To date I thought the "accepted truth" was

1) In the first few months of the war, U-boats gave the British very
hard time. This was largely due to British short comings, i.e lack of
organisation and suitable escort ships. The Germans referred to this
period as "the happy days"

2) Over the next 2 years, things improved for the British. From Ultra
they knew how U-boats were deployed. They also gained more experience
in managing convoys and more/better escort ships. For Germany, the
"happy days" were over. Never the less, Britain's long term survival
was still uncertain.

3) When the US was forced into the war, U-boats attacked US ships on US
east coast. For several months the US refused to take what the british
considered to appropriate precautions. No convoys, would not darken
ship at night, coastal towns would not dim their lights so ships were
clearly silhouetted at night. Germany called the period "the 2nd happy
days".

4) Eventually the US got its act together and the "2nd happy days" were
over.

5) Longterm success for the allies remained uncertain for some time. As
late as February 1943, some British staff believed they could not win.
Then in May 1943 it all "came toga]ether" for the allies and their
longterm success was assured, though they may not have realised at the time.


Now then, the video I saw recently (on You-Tube) was mainly about diving
on an unknown U-bout, sunk off US east coast. Never the less, they
"explained" some of the history. This history included an explanation
for the "2nd happy days".

They claimed that Admiral King refused to convoy ships on US coast
because he lacked suitable escort ships. "Ships in a badly defended
convoy were in more danger than ships sailing alone". I can see that
MAY be valid, but these ships still sailed with navigation lights on and
coastal towns did not "brown out".

He also claimed it was more important to escort troop ships rather than
freighters. The video demonstrated the validity of this by stating that
no troops ships were ever lost. Sounds good except that I believe these
troop shipments began much later, after the "2nd happy days" were over
(with operation Torch?).

The video closed by claiming all the fuss about U-boats was over stated
because they only sank about 1% percent of all allied shipping.




I saw a video recently that challenged what I thought was "accepted
truth" about the battle of the Atlantic.
To date I thought the "accepted truth" was

1) In the first few months of the war, U-boats gave the British very
hard time. This was largely due to British short comings, i.e lack of
organisation and suitable escort ships. The Germans referred to this
period as "the happy days"

2) Over the next 2 years, things improved for the British. From Ultra
they knew how U-boats were deployed. They also gained more experience
in managing convoys and more/better escort ships. For Germany, the
"happy days" were over. Never the less, Britain's long term survival
was still uncertain.

3) When the US was forced into the war, U-boats attacked US ships on US
east coast. For several months the US refused to take what the british
considered to appropriate precautions. No convoys, would not darken
ship at night, coastal towns would not dim their lights so ships were
clearly silhouetted at night. Germany called the period "the 2nd happy
days".

4) Eventually the US got its act together and the "2nd happy days" were
over.

5) Longterm success for the allies remained uncertain for some time. As
late as February 1943, some British staff believed they could not win.
Then in May 1943 it all "came toga]ether" for the allies and their
longterm success was assured, though they may not have realised at the time.


Now then, the video I saw recently (on You-Tube) was mainly about diving
on an unknown U-bout, sunk off US east coast. Never the less, they
"explained" some of the history. This history included an explanation
for the "2nd happy days".

They claimed that Admiral King refused to convoy ships on US coast
because he lacked suitable escort ships. "Ships in a badly defended
convoy were in more danger than ships sailing alone". I can see that
MAY be valid, but these ships still sailed with navigation lights on and
coastal towns did not "brown out".

He also claimed it was more important to escort troop ships rather than
freighters. The video demonstrated the validity of this by stating that
no troops ships were ever lost. Sounds good except that I believe these
troop shipments began much later, after the "2nd happy days" were over
(with operation Torch?).

The video closed by claiming all the fuss about U-boats was over stated
because they only sank about 1% percent of all allied shipping.



I believe the claims made on this video just don't add up. Am I right?

[Rich Rostrom]

Post by Chris Allen
I saw a video recently that challenged what I thought was "accepted
truth" about the battle of the Atlantic.
To date I thought the "accepted truth" was
1) In the first few months of the war, U-boats gave the British very
hard time. This was largely due to British short comings, i.e lack of
organisation and suitable escort ships. The Germans referred to this
period as "the happy days"

Where on earth did you get this idea? When the
war started, Germany had only 57 U-boats in
service, of which 31 were Type II coastal boats.

Furthermore, the U-boats had to sail from Germany,
which meant they had to pass across the North Sea
and around the British Isles to get to the convoy
lanes in the open Atlantic. This extra distance
took weeks off a U-boat's patrol period.

Also, there were serious problems with German
torpedos, with many running off course or failing
to explode. Several major Allied warships escaped
sinking because of this.

For these reasons, the U-boats were not especially
effective for the first eight months of the war.
They averaged less than 100,000 tons sunk per month,
and 22 U-boats were sunk by the Allies.

The U-boats scored some dramatic successes - sinking
the liner ATHENIA, the carrier COURAGEOUS, and the
battleship ROYAL OAK (in Scapa Flow!), but overall
were ineffective.

On the other hand, British ASW _was_ less effective
than expected. The British had thought that sonar
(which they called asdic) would completely defeat
submarines; they soon learned it wasn't a panacea.

(During the first four months of the war, weekend
leaves for Admiralty staff started on Friday mornings.
After ROYAL OAK was sunk, they started on Saturday
afternoons.)

Post by Chris Allen
2) Over the next 2 years, things improved for the British. From Ultra
they knew how U-boats were deployed. They also gained more experience
in managing convoys and more/better escort ships. For Germany, the
"happy days" were over. Never the less, Britain's long term survival
was still uncertain.

Again, much confusion. During and after the fall of
France, the U-boats became far more effective. The
Germans fixed their torpedo problems, and the U-boats
moved to bases in Norway and on the west coast of
France, where they were much closer to the convoy lanes.
Also, the French navy dropped out of the war, and the
British navy suddenly was stretched much thinner. (There
was now a Mediterranean theater too.)

U-boats sank 273,219 tons in May 1940, 471,496 tons in June,
and at least 350,000 tons each month for the rest of
1940. Sinkings peaked at 653,960 tons in April 1941.

In part this was due to German tactical innovation.
Initially, boats patrolled individually, attacking
whatever ships came by. Then as the numbers on patrol
went up, they adopted the "wolfpack" tactic. U-boat
HQ on shore would position a dozen boats in a long
N-S patrol line, watching for convoys. When a convoy
was sighted, all the boats in the group would gather
ahead of the convoy (surfaced U-boats were faster
than convoys). Then the entire group would attack
the convoy at night, overwhelming the escorts.

During this period the British had no German Navy Enigma
intelligence. They also had very few long-range patrol
aircraft and no escort carriers. They sank only 20 U-boats
in 14 months.

It was this period, not the "first few months of the war",
that was called "the happy time".

In spring 1941, the British made a concerted effort to
capture naval Enigma material. This culminated in the
boarding of U-110 in May 1941. Bletchley Park began
reading navy Enigma in June.

This made a huge difference. Knowing the positions of
the patrol lines, the Admiralty steered the convoys
around them. This didn't always work; one convoy was
spotted because a U-boat captain misread his orders
and was many miles out of position. Other convoys were
spotted by German long-range aircraft flying from France.
And Britain began sending aid to the beleaguered USSR
via Murmansk, which meant running a gauntlet of U-boats
and aircraft based in Norway.

Still, for the next several months, shipping losses
dropped by 2/3.

Post by Chris Allen
3) When the US was forced into the war, U-boats attacked US ships on US
east coast. For several months the US refused to take what the british
considered to appropriate precautions. No convoys, would not darken
ship at night, coastal towns would not dim their lights so ships were
clearly silhouetted at night. Germany called the period "the 2nd happy
days".

This is pretty much accurate - except that the problem
with coastal cities was that they would only _dim_ their
lights, and the "dimout" was not enough.

It also leaves out a critical factor: in February 1942,
the Germans adopted a new Enigma key for U-boats only.
This key used an enhanced Enigma machine and additional
scrambler wheels - it could not be read.

On top of this was numbers: the Germans had 300 U-boats
in service, nearly all long-range types. Over the next
10 months the Germans sank almost 7 million tons.

Post by Chris Allen
4) Eventually the US got its act together and the
"2nd happy days" were over.

There's some truth to that, but there are other important
factors. The Allied navies (British as well as U.S)
dramatically improved their ASW tactics in August 1942,
more than tripling U-boat kills.

The key event was the capture of Enigma material from a
foundering U-boat at the end of October. (The two British
sailors who retrieved it went down with the U-boat.) With
that material, Bletchley Park broke the U-boat key; sinkings
dropped by half in December.

Post by Chris Allen
5) Longterm success for the allies remained uncertain for some time. As
late as February 1943, some British staff believed they could not win.
Then in May 1943 it all "came togaether" for the allies and their
longterm success was assured, though they may not have realised at the time.

The next five months were a "see-saw" period. The Germans
now had 400 U-boats in service, and the Allies were still
short of escorts, long-range aircraft, and jeep carriers.
The Germans tweaked U-boat Enigma in March 1943, blinding
Bletchley Park for a month, and sank nearly 700,000 tons.

May 1943 is indeed "when it all came together". The Allies
deployed airborne search radar, read Enigma, and sent out
the first wave of jeep carriers; they sank 41 U-boats. In
June the U-boats "retreated" to the less patrolled southern
Atlantic, and sank only 123,825 tons. When they attacked
again in July, they sank 365,398 tons, but lost 37 boats.

In the remaining 22 months of the war, the U-boats sank
another 800,000 tons, but lost more boats sunk than Allied
ships sunk.

Post by Chris Allen
Now then, the video I saw recently (on You-Tube) was mainly about diving
on an unknown U-bout, sunk off US east coast. Never the less, they
"explained" some of the history. This history included an explanation
for the "2nd happy days".
They claimed that Admiral King refused to convoy ships on US coast
because he lacked suitable escort ships. "Ships in a badly defended
convoy were in more danger than ships sailing alone".

That's not entirely true as a rule. However, convoying
also greatly reduces the effective use of ships and
ports. Ports work most efficiently when there is a
continuous stream of ships moving in and out. Convoying
brings many ships in at a time, and ships have to wait
while others are unloaded and loaded.

And it is true that the U.S. did not have enough escorts
for proper convoy operations; King's policy _was_ as
much a necessity as a choice.

Post by Chris Allen
I can see that MAY be valid, but these ships still sailed
with navigation lights on and coastal towns did not "brown out".
He also claimed it was more important to escort troop ships rather than
freighters. The video demonstrated the validity of this by stating that
no troops ships were ever lost. Sounds good except that I believe these
troop shipments began much later, after the "2nd happy days" were over
(with operation Torch?).

TORCH was 8 November 1943. That month the U-boats sank 812,867
tons, the second worst month of the war. And there were lots
of troop shipments before TORCH - from the U.S. to Britain,
and from Britain to the Middle East and India.

Maybe no American troopships were sunk, but
I'm pretty sure some British troopships were.

Post by Chris Allen
The video closed by claiming all the fuss about U-boats was over stated
because they only sank about 1% percent of all allied shipping.

That's sometimes asserted. But it overlooks
several things. First, every ship lost meant
the loss (or non-delivery) not only of cargo
on board at the time, but also of all future
deliveries.

It also ignores the different impact of
shipping in the Pacific (U.S. to Hawaii, say)
compared with shipping from the U.S. to
Britain, and shipping at different times
(the volume of shipping was higher in the
last year of the war).

It should be recalled that Churchill said
the only thing which ever really scared
him was the U-boat threat.

[a425couple]

Post by Rich Rostrom

I saw a video recently ---

U-boats sank 273,219 tons in May 1940, 471,496 tons in June,
and at least 350,000 tons each month for the rest of
1940. Sinkings peaked at 653,960 tons in April 1941.

I'd suggest the book I mentioned a couple days ago,
"Black May: The Epic Story of the Allies' Defeat of the German
U-Boats in May 1943" By Michael Gannon

If you put in this:
http://www.amazon.com/Black-May-Allies-Defeat-U-Boats/dp/1591143047
and then click the "read inside" and I think
the "Prologue" is very informative for figures.
The loss figures & predictions are sometimes quite informative
of attitudes at the time.

In case that does not work, I'll try typing some:
"Put in the simplest terms, Admiral Donetz and his U-Boats
were engaged in a tonnage battle with Allied trade, that is,
in a campaign to sink more British and American merchant ship
tonnage than the Allies could replace with new construction.
--Donitz calculated in 1940 -- they 'would need to sink'
700,000 GRT.
The British had estimated that 600,000 would-- do them in."
"best that he had done -- 125 ship for 584,788 GRT -- May 1942 --
and -- 131 ships for 616,904 -- in June 1942 --
and -- 118 ships for -- record 743,321 GRT in November 1942.
The numbers fell off in the following three months."
----- March 1943 started with very high numbers,, then eased for
"--105 ships for 590,234"

But all was changing for US shipyards were really pumping
out ships, so correct new required figure would be 1.3M!!!
But still, all was pointing toward climatic May 1943.
Allied merchant losses really dropped.
German U-boat losses soared!

[Merlin Dorfman]

On Fri, 28 Feb 2014 16:48:29 -0500, a425couple wrote:

..

Post by a425couple
I'd suggest the book I mentioned a couple days ago,
"Black May: The Epic Story of the Allies' Defeat of the German U-Boats
in May 1943" By Michael Gannon

Amazon.com is selling the Kindle (e-book) version of Black May for 99
cents (US $0.99)
www.amazon.com/gp/product/B003YCOOYY/ref=em_si_text

[Chris Allen]

Thanks for sorting out several confused notions.
I knew Germany began with much fewer U-boats than Donitz wanted but did
not realize it took them so long to get thier own act together.

You also explained that initial US "failure" was due more to overall
lack of undesratnding by many groups and lack of resources rather than
"bad policy".

2 Qusetions.

1) Did US coastal shipping continue night sailing with all navigation
lighs still on? Certainly 1 video says they did. In light of what you
(and others) say, I finnd tis hard to belive.

2) Can you explain you reference to "jeep carriers" ?
I've not heard the term in any discussion about Battel of Atlantic.

[Michael Emrys]

Post by Chris Allen
Can you explain you reference to "jeep carriers" ?
I've not heard the term in any discussion about Battel of Atlantic.

"Jeep Carriers" is a nickname given to CVEs or escort carriers. Heard of
those? Small aircraft carriers built on merchant hulls and merchant
machinery. Not very fast, but fast enough to run down submarines and
keep up with convoys. They began appearing in useful numbers in the
spring of 1943 and were eventually built in large numbers. I think they
carried no more than a couple dozen aircraft divided between fighters
and torpedo bombers rigged for A/S work. Their advent meant that convoys
could now enjoy an air escort even when out of range of land based air.
They were also organized into Hunter-Killer groups of one CVE and three
each of DDs and DDEs to track down U-boats in the open ocean. This was a
little less successful than convoy escort but did succeed in destroying
the "Milch Cow" tanker subs that the KM sent out to refuel and replenish
their attack subs on patrol.

Michael

[Geoffrey Sinclair]

Post by Chris Allen
Thanks for sorting out several confused notions.
I knew Germany began with much fewer U-boats than Donitz wanted but did
not realize it took them so long to get thier own act together.

There is always a learning curve, part of the reason the 1942
operations were so successful for the Germans was the
experienced U-boat fleet was taking on largely inexperienced
forces in the western Atlantic and Caribbean.

Post by Chris Allen
You also explained that initial US "failure" was due more to overall lack
of undesratnding by many groups and lack of resources rather than "bad
policy".

Bad policy resulted from the lack of understanding. Yes it was
a failure by many people and organisations, plus the inevitable
inertia when moving from peace to war.

In the second half of 1941, as part of the policy of spreading the
war U-boats began operating south of the Equator. At distances
from their bases comparable to the distance to New York.

Post by Chris Allen
2 Qusetions.
1) Did US coastal shipping continue night sailing with all navigation
lighs still on? Certainly 1 video says they did. In light of what you
(and others) say, I finnd tis hard to belive.

Yes for a time, the system remained in peace time configuration,
it reduced the inevitable maritime risks and increased port
efficiency.

With convoys there was an increase in collision damage because
so many ships were crowded together in some ports. In an extreme
case in New York on 1 April 1943 defects on ships and fog induced
collisions meant 20% of the cargo loaded was not shipped

Post by Chris Allen
2) Can you explain you reference to "jeep carriers" ?
I've not heard the term in any discussion about Battel of Atlantic.

Escort carriers, CVE in the USN designation system, built on
merchant ship hulls. The RN tended to use them as convoy
escorts, the USN was more interested in using them as part
of hunter killer units.

Geoffrey Sinclair
Remove the nb for email.

[Paul F Austin]

Post by Chris Allen
3) When the US was forced into the war, U-boats attacked US ships on US
east coast. For several months the US refused to take what the british
considered to appropriate precautions. No convoys, would not darken
ship at night, coastal towns would not dim their lights so ships were
clearly silhouetted at night. Germany called the period "the 2nd happy
days".
4) Eventually the US got its act together and the "2nd happy days" were
over.

....

Post by Chris Allen
Now then, the video I saw recently (on You-Tube) was mainly about diving
on an unknown U-bout, sunk off US east coast. Never the less, they
"explained" some of the history. This history included an explanation
for the "2nd happy days".
They claimed that Admiral King refused to convoy ships on US coast
because he lacked suitable escort ships. "Ships in a badly defended
convoy were in more danger than ships sailing alone". I can see that
MAY be valid, but these ships still sailed with navigation lights on and
coastal towns did not "brown out".
He also claimed it was more important to escort troop ships rather than
freighters. The video demonstrated the validity of this by stating that
no troops ships were ever lost. Sounds good except that I believe these
troop shipments began much later, after the "2nd happy days" were over
(with operation Torch?).

There's rather less there than meets the eye. Convoys provide herd
protection even there are no escorts. The Operations Research analysis
showed that in the open ocean the probability of intercept of any given
convoy was about the same as that of any single ship traveling alone.
That sound as if unaccompanied ships would have an advantage. The
difference comes when you consider what happens when N ships in convoy
meet one or more submarines compared to N ships traveling alone.

In the convoy case, the attackers have only a limited window before the
convoy sails on and before the attackers run out of munitions to make
kills. Even without escorts, submarines have limited time and munitions
for any given battle. That limits the number of ships that can be lost
in that intercept. Let's say that the average attack is by 2 U-boats
that between them can sink 10 ships before the convoy sails on. The
probability-weighted loss is Pi (the probability of intercept) times the
number of losses, in this case 5. As long as Pi is small, say less than
50%, each convoy dispatched would lose on the average 5 ships out of a
notional 20 ship convoy (25%). That sounds bad.

When N ships sail individually, the number of ships non-intercepted is
(1-Pi)^N and the number of intercepts is 1-(1-Pi)^N. In each intercept
case, the submarine will have a high Pk. For our 50% Pi case, the same
20 ships would be intercepted half the time and sunk for a loss of 10
ships, much worse.

Darkening ship and blackouts were no-brainers, the Roosevelt
administration and the USN share blame here about equally.

In King's defense, individual ships captains _hated_ convoys. They
delayed sailing and cost the owners money. It wasn't until the lessons
of the cost of sunk ships hit home that owners were willing to pay the
price of sailing in convoy.

Certainly there were a shortage of escorts in 1942 and they should have
been assigned on a priority basis but that is no justification for not
operating convoys.

Paul

[c***@gmail.com]

Post by Paul F Austin
The Operations Research analysis
showed that in the open ocean the probability of intercept of any given
convoy was about the same as that of any single ship traveling alone.

That is true for open ocean work. It's not necessarily true for coastal
shipping under discussion here, because there you have choke points (e.g.
Cape Hatteras) which invalidates the 'ocean is really huge' effect of convoy
protection.

On balance, the decision to not run unescorted coastal convoys was probably
a mistake, but it is not nearly as clear-cut as the calculation for blue
water convoying.

Also, a note on Rich's otherwise excellent message (which seemed to be based
largely on Clay Blair's two volume Hitler's U-Boat War, if someone is
interested in reading more), he had a minor typo on the date of Torch, which
was of course November 1942, not 1943.

Chris Manteuffel

[Paul F Austin]

Post by c***@gmail.com

Post by Paul F Austin
The Operations Research analysis
showed that in the open ocean the probability of intercept of any given
convoy was about the same as that of any single ship traveling alone.

That is true for open ocean work. It's not necessarily true for coastal
shipping under discussion here, because there you have choke points (e.g.
Cape Hatteras) which invalidates the 'ocean is really huge' effect of convoy
protection.

I don't quite agree here. Hatteras in particular is a high traffic area
because mariners want to shave the Cape to save time and bunkers. By
swinging farther out, submarine's area of coverage would increase a lot,
being more like open ocean. There are unavoidable choke points, like the
mouth of Delaware and entry into the ports of New York but these areas
can be patrolled and defended much more easily using scheduling and
shore based air and sea assets. By scheduling convoys into and out of
ports to coincide with close to shore protection, even without escorts
the protection afforded to a given number of ships is higher than from
random sailings.

Paul

[Rich Rostrom]

Post by c***@gmail.com
Also, a note on Rich's otherwise excellent message (which seemed to be based
largely on Clay Blair's two volume Hitler's U-Boat War

Never actually read that.

I've read all of Dan Gallery's books, including
_20,000,000 Tons Under the Sea_ (which has a
statistical appendix), and quite a lot about Enigma.

The data about U-boat numbers and sinkings was
compiled by me from H. T. Lenton's reference books.

[Roman W]

On Thu, 27 Feb 2014 18:15:41 -0500, Paul F Austin

Post by Paul F Austin
In the convoy case, the attackers have only a limited window before the
convoy sails on and before the attackers run out of munitions to make
kills. Even without escorts, submarines have limited time and

munitions

Post by Paul F Austin
for any given battle. That limits the number of ships that can be lost
in that intercept. Let's say that the average attack is by 2

U-boats

Post by Paul F Austin
that between them can sink 10 ships before the convoy sails on. The
probability-weighted loss is Pi (the probability of intercept)

times the

Post by Paul F Austin
number of losses, in this case 5. As long as Pi is small, say less than
50%, each convoy dispatched would lose on the average 5 ships out of a
notional 20 ship convoy (25%). That sounds bad.
When N ships sail individually, the number of ships non-intercepted is
(1-Pi)^N and the number of intercepts is 1-(1-Pi)^N. In each

intercept

Post by Paul F Austin
case, the submarine will have a high Pk. For our 50% Pi case, the same
20 ships would be intercepted half the time and sunk for a loss of 10
ships, much worse.

I think you got your maths totally wrong. Did you mean N*Pi ships
intercepted on average? (1-Pi)^N would be very small for Pi=0.5 and
N=20.

Also note that the number of ships intercepted, if sailing
independently, is limited by the number of U-boats operating. An
U-boat cannot be in two different places at the same time (although
if not submerged, it is probably faster than a merchant ship). Hence,
Pi*N will not be true for large N.

RW

[Alan Meyer]

On 02/27/2014 06:15 PM, Paul F Austin wrote:
...

Post by Paul F Austin
In the convoy case, the attackers have only a limited window before the
convoy sails on and before the attackers run out of munitions to make
kills.

...

But the convoy will never be able to sail on.

As Roman W. points out in a later post, the surface speed of a U-boat
(>17 knots for a Type VIIC) is faster than all but the fastest merchant
ships. In convoy it's even worse for the merchantman because they're
limited to the speed of the slowest ship.

The U-boats also have radios and would be communicating convoy course
and speed for later interception by other boats.

Post by Paul F Austin
Even without escorts, submarines have limited time and munitions
for any given battle.

But without escorts, it's easy for the subs to approach closely enough,
especially at night, to fire torpedoes at point blank range. In a
convoy, even a miss might strike another ship sailing nearby. Assuming
14 torpedoes in Type VIIC subs (the most common type), it might be
reasonable to assume 10+ hits against an unescorted convey.

One small advantage to the convoy would be that a U-boat would have less
chance in a gun attack against guns from multiple merchant ships. But
as long as more than one submarine can attack, there are enough
torpedoes available that gun attacks might be entirely unnecessary.

I think an unescorted convoy would be massacred if they stayed together.
If they scattered, some of the ships would get away, but losses might
still be pretty high - especially among the highest value targets that
would be pursued first.

I'm speculating here, but it seems possible to me that a convoy would
also put out a lot more smoke and underwater noise and therefore be
detectable by patrolling U-boats at a greater range. If so, then the
likelihood of detection of an individual convoy would be greater than
the likelihood of detection of an individual ship. If the speed is
limited to the speed of the slowest ship, then the average speed will
also be less than for the average of individual ships and the time
available for detection (and attack) will be greater.

For these reasons, I would expect that unescorted convoy losses would be
much higher than for individual sailings. I would think it's the
escort, not the clustering, that protects the convoy.

Alan

[Roman W]

Post by Alan Meyer
I'm speculating here, but it seems possible to me that a convoy would
also put out a lot more smoke and underwater noise and therefore be
detectable by patrolling U-boats at a greater range. If so, then the

And radio traffic.

RW

[Geoffrey Sinclair]

Post by Alan Meyer
...

Post by Paul F Austin
In the convoy case, the attackers have only a limited window before the
convoy sails on and before the attackers run out of munitions to make
kills.

...
But the convoy will never be able to sail on.

That surely is a function of the number of ships and submarines.

Post by Alan Meyer
As Roman W. points out in a later post, the surface speed of a U-boat (>17
knots for a Type VIIC) is faster than all but the fastest merchant ships.
In convoy it's even worse for the merchantman because they're limited to
the speed of the slowest ship.

Yes, provided the U-boat can use that speed, in other words
a lack of air escorts.

Post by Alan Meyer
The U-boats also have radios and would be communicating convoy course and
speed for later interception by other boats.

Correct, it then becomes what U-boats are in range given the
need to form scouting lines to find the merchant ships in the
first place, plus the inevitable flow of new U-boat patrols
while others return to base.

Of course the merchant ships would also be using their
radios, reporting the attacks.

However Paul is talking about the US coastal shipping, which
went via well defined routes. They also had access to at least
air cover during daylight hours given their positions, provided
the ships were in a convoy.

They also had some surface escorts available.

Post by Alan Meyer

Post by Paul F Austin
Even without escorts, submarines have limited time and munitions
for any given battle.

But without escorts, it's easy for the subs to approach closely enough,
especially at night, to fire torpedoes at point blank range. In a convoy,
even a miss might strike another ship sailing nearby. Assuming 14
torpedoes in Type VIIC subs (the most common type), it might be reasonable
to assume 10+ hits against an unescorted convey.

Except that seems to be an over estimate, given the problems
of firing solutions even by day. The USN discovered that there
was an effect of being too close, misses went up.

Of course some crews were better shots than others.

Post by Alan Meyer
One small advantage to the convoy would be that a U-boat would have less
chance in a gun attack against guns from multiple merchant ships. But as
long as more than one submarine can attack, there are enough torpedoes
available that gun attacks might be entirely unnecessary.

This is by far the worst case, a big constraint is the time taken for the
manual reloading of the torpedo tubes, tending to limit the submarine
to a couple of attacks per tube per night.

Hence why they preferred ships sailing individually.

Post by Alan Meyer
I think an unescorted convoy would be massacred if they stayed together.
If they scattered, some of the ships would get away, but losses might
still be pretty high - especially among the highest value targets that
would be pursued first.

Given the claim is all the U-boats within range are converging it
means the merchant ships are effectively going one on one with
any U-boat they encounter, U-boats that are confident there is
no escort anywhere near.

Essentially you have set up a convoy with no escort, with no
reinforcement escorts within range for days and encountering
a group of U-boats that do not need much time to concentrate
or even catch up the the convoy.

It would be rather one sided.

North Atlantic convoys were not that isolated.

US coastal ships always had the option of entering port.

Post by Alan Meyer
I'm speculating here, but it seems possible to me that a convoy would also
put out a lot more smoke and underwater noise and therefore be detectable
by patrolling U-boats at a greater range. If so, then the likelihood of
detection of an individual convoy would be greater than the likelihood of
detection of an individual ship. If the speed is limited to the speed of
the slowest ship, then the average speed will also be less than for the
average of individual ships and the time available for detection (and
attack) will be greater.
For these reasons, I would expect that unescorted convoy losses would be
much higher than for individual sailings. I would think it's the escort,
not the clustering, that protects the convoy.

In practice finding convoys was about as hard as finding
individual ships. The loss rates for independent sailings
was higher than for convoys.

Clustering reduces the chances the merchant ship will
be found, after that any air escort makes it hard for a
WWII submarine to close the distance, after that are
the surface escorts helping make it harder to achieve a
firing position.

Geoffrey Sinclair
Remove the nb for email.

[Mario]

Post by Geoffrey Sinclair

Post by Alan Meyer
I'm speculating here, but it seems possible to me that a
convoy would also put out a lot more smoke and underwater
noise and therefore be detectable by patrolling U-boats at a
greater range. If so, then the likelihood of detection of an
individual convoy would be greater than the likelihood of
detection of an individual ship. If the speed is limited to
the speed of the slowest ship, then the average speed will
also be less than for the average of individual ships and the
time available for detection (and attack) will be greater.
For these reasons, I would expect that unescorted convoy
losses would be much higher than for individual sailings. I
would think it's the escort, not the clustering, that
protects the convoy.

In practice finding convoys was about as hard as finding
individual ships. The loss rates for independent sailings
was higher than for convoys.
Clustering reduces the chances the merchant ship will
be found, after that any air escort makes it hard for a
WWII submarine to close the distance, after that are
the surface escorts helping make it harder to achieve a
firing position.

Many fish gather in schools as a defence from predators.

[Roman W]

On Thu, 03 Apr 2014 10:41:06 -0400, "Geoffrey Sinclair"

Post by Geoffrey Sinclair
Yes, provided the U-boat can use that speed, in other words
a lack of air escorts.

Yes. My argument was about unescorted convoys.

RW

[Michael Emrys]

Post by Alan Meyer
I think an unescorted convoy would be massacred if they stayed together.

The numbers do not bear you out. Once convoying was instituted, losses
went down, dramatically. Even unescorted convoys on average lost fewer
ships because many of them went undiscovered, or if discovered were not
attacked by sufficient numbers of U-boats or over a long enough period
of time to do the kind of massive destruction you are positing.

Michael

[Alan Meyer]

Post by Michael Emrys

Post by Alan Meyer
I think an unescorted convoy would be massacred if they stayed together.

The numbers do not bear you out. Once convoying was instituted, losses
went down, dramatically. Even unescorted convoys on average lost fewer
ships because many of them went undiscovered, or if discovered were not
attacked by sufficient numbers of U-boats or over a long enough period
of time to do the kind of massive destruction you are positing.
Michael

I confess that I was thinking about the mid-Atlantic, not the eastern
seaboard of the United States. Conditions off the coast are different
because, as others have noted, of the possibility of summoning help or
getting to safety. Help would not arrive in time to save a ship but
might save at least some ships in a convoy under attack that would have
been sunk otherwise. Going into harbors or, almost as good, into
shallow waters, could also provide some help, though it should be
understood that the nearest harbor would typically have been hours, not
minutes, away. But at least it wasn't days away.

Until 1943, there was a large open area of the Atlantic that was not
covered by any aircraft. From the accounts that I read, convoys going
through that "black hole" or "mid-Atlantic gap" area were not able to
summon help. Escorts capable of ranging into the mid-Atlantic were in
high demand everywhere and the more available corvettes and later
frigates did not have the range or speed to get to a mid-ocean convoy
that was under attack.

A convoy steaming at 8 knots across a 1,000 mile gap would, in theory,
take 5.2 days to cross. In practice it would be worse because convoys
could be delayed by engineering problems and by zigzagging.

So, I'm prepared to believe that an unescorted Atlantic convoy did
better than ships sailing independently if that's what the history in
fact shows, but I do find it surprising.

Perhaps this would have happened during the periods in which the British
had broken the U-boat codes. I don't know how practical it would be to
route 40 individual ships, any one of which could pick up a U-boat tail,
and some of which would not have been good security risks for exchanging
information about routing with England. But in the absence of such
routing, it's hard for me to understand how an unescorted convoy would
do better than independent sailors.

Alan

[Michael Emrys]

...it's hard for me to understand how an unescorted convoy would do better
than independent sailors.

Mainly because it's a big ocean, and by concentrating ships in a single
area of it, you increase the chance that none of them will be spotted by
a U-boat. By spreading them all over the sea lanes by independent
sailings, what you are doing is increasing the area containing ships and
making it much more likely that at least some will be spotted, tracked,
and attacked. Which in fact is what happened before convoying was
instituted.

Michael

[Paul F Austin]

Post by Michael Emrys

...it's hard for me to understand how an unescorted convoy would do better
than independent sailors.

Mainly because it's a big ocean, and by concentrating ships in a single
area of it, you increase the chance that none of them will be spotted by
a U-boat. By spreading them all over the sea lanes by independent
sailings, what you are doing is increasing the area containing ships and
making it much more likely that at least some will be spotted, tracked,
and attacked. Which in fact is what happened before convoying was
instituted.

The probability of intercept of any single ship sailing alone (on the
scale of oceans and the circle of visibility of a low lying ship like a
U-Boat) is the same as the probability of intercept of a convoy. The
consequences in terms of ships lost if a convoy is intercepted but as
long as the probability of intercept is relatively small, the number of
losses on average is smaller when ships are "clumped" in convoys. Most
of the time, they don't get intercepted, whereas with hundreds of
independent sailings, the number of single ships intercepted and sunk
can be substantial. The _worst_ case of a convoy being intercepted can
result in large numbers of ships lost that time but likely not the next
time.

The Operations Analysis gets much more complicated when both sides are
using signals intelligence so both intercepts and avoidance are
non-random and if aircraft enter the picture, so that large ocean areas
can be either covered to detect ships in convoy or large areas can be
sanitized free of submarines by raising the probability of detection of
a U-boat on the surface (where they were most of the time and _had_ to
be during the daytime in order to spot ships), the OR gets more complex
still.

I make no claims of being a competent Operations Analyst. The above is
simply what was reported in histories of the Battle of the Atlantic.

Paul

[Roman W]

On Sat, 05 Apr 2014 22:10:22 -0400, Paul F Austin

Post by Paul F Austin
The probability of intercept of any single ship sailing alone (on the
scale of oceans and the circle of visibility of a low lying ship like a
U-Boat) is the same as the probability of intercept of a convoy. The

I doubt that. For one, the convoy is louder.

Post by Paul F Austin
I make no claims of being a competent Operations Analyst. The above is
simply what was reported in histories of the Battle of the Atlantic.

By Operations Analysts, or by historians quoting historians quoting
Operations Analysts?

RW

[Paul F Austin]

Post by Roman W
On Sat, 05 Apr 2014 22:10:22 -0400, Paul F Austin

Post by Paul F Austin
The probability of intercept of any single ship sailing alone (on

the

Post by Paul F Austin
scale of oceans and the circle of visibility of a low lying ship

like a

Post by Paul F Austin
U-Boat) is the same as the probability of intercept of a convoy.

The
I doubt that. For one, the convoy is louder.

Post by Paul F Austin
I make no claims of being a competent Operations Analyst. The above

is

Post by Paul F Austin
simply what was reported in histories of the Battle of the Atlantic.

By Operations Analysts, or by historians quoting historians quoting
Operations Analysts?
RW

Books written by historians, who are trained to seek primary sources,
either the people (rarely available) or the records they produce. The
kind of books you refer to, whose main sources are secondary are
popularizations rather than historiography. That section of my library
is down at the other house, so I can't give you references right now.

Paul

[GFH]

Post by Paul F Austin
Books written by historians, who are trained to seek primary sources,
either the people (rarely available) or the records they produce. The
kind of books you refer to, whose main sources are secondary are
popularizations rather than historiography. That section of my library
is down at the other house, so I can't give you references right now.

Other books, even fiction, can give a very
good impression of a convoy. I recommend:
Forester, C.S., The Good Shepherd. 1955
Early in the war (for the USA). Early
wolf pack experiences. Seen through the
eyes of the senior officer (commodore, if
you will) of the four escort ships.

GFH

[Paul F Austin]

Post by GFH

Post by Paul F Austin
Books written by historians, who are trained to seek primary sources,
either the people (rarely available) or the records they produce. The
kind of books you refer to, whose main sources are secondary are
popularizations rather than historiography. That section of my library
is down at the other house, so I can't give you references right now.

Other books, even fiction, can give a very
Forester, C.S., The Good Shepherd. 1955
Early in the war (for the USA). Early
wolf pack experiences. Seen through the
eyes of the senior officer (commodore, if
you will) of the four escort ships.

I really like Forester and have read most of his books but the more I
study, the less I treat him as a reliable source for "how it was".

Paul

[GFH]

Post by Paul F Austin

Post by GFH

Post by Paul F Austin
Books written by historians, who are trained to seek primary sources,
either the people (rarely available) or the records they produce. The
kind of books you refer to, whose main sources are secondary are
popularizations rather than historiography. That section of my library
is down at the other house, so I can't give you references right now.

Other books, even fiction, can give a very
Forester, C.S., The Good Shepherd. 1955
Early in the war (for the USA). Early
wolf pack experiences. Seen through the
eyes of the senior officer (commodore, if
you will) of the four escort ships.

I really like Forester and have read most of his books but the more I
study, the less I treat him as a reliable source for "how it was".

I suspect that you have not read "The Good
Shepherd". It is not a Hornblower novel.

GFH

[Paul F Austin]

Post by GFH

Post by Paul F Austin

Post by GFH

Post by Paul F Austin
Books written by historians, who are trained to seek primary sources,
either the people (rarely available) or the records they produce. The
kind of books you refer to, whose main sources are secondary are
popularizations rather than historiography. That section of my library
is down at the other house, so I can't give you references right now.

Other books, even fiction, can give a very
Forester, C.S., The Good Shepherd. 1955
Early in the war (for the USA). Early
wolf pack experiences. Seen through the
eyes of the senior officer (commodore, if
you will) of the four escort ships.

I really like Forester and have read most of his books but the more I
study, the less I treat him as a reliable source for "how it was".

I suspect that you have not read "The Good
Shepherd". It is not a Hornblower novel.

I have read _The Good Shepherd_. It's exhausting to read and gives a
feel for how exhausting _real_ ASW was and is.

Paul

[GFH]

Post by Paul F Austin

Post by GFH

Post by Paul F Austin

Post by GFH

Post by Paul F Austin
Books written by historians, who are trained to seek primary sources,
either the people (rarely available) or the records they produce. The
kind of books you refer to, whose main sources are secondary are
popularizations rather than historiography. That section of my library
is down at the other house, so I can't give you references right now.

Other books, even fiction, can give a very
Forester, C.S., The Good Shepherd. 1955
Early in the war (for the USA). Early
wolf pack experiences. Seen through the
eyes of the senior officer (commodore, if
you will) of the four escort ships.

I really like Forester and have read most of his books but the more I
study, the less I treat him as a reliable source for "how it was".

I suspect that you have not read "The Good
Shepherd". It is not a Hornblower novel.

I have read _The Good Shepherd_. It's exhausting to read and gives a
feel for how exhausting _real_ ASW was and is.

Yes, and the commander's considerations: fuel,
depth charges on hand, distance to go, moral of
the men, enduring action for days on end, etc.

GFH

[Paul F Austin]

Post by GFH

Post by Paul F Austin

Post by GFH

Post by Paul F Austin

Post by GFH

Post by Paul F Austin
Books written by historians, who are trained to seek primary sources,
either the people (rarely available) or the records they produce. The
kind of books you refer to, whose main sources are secondary are
popularizations rather than historiography. That section of my library
is down at the other house, so I can't give you references right now.

Other books, even fiction, can give a very
Forester, C.S., The Good Shepherd. 1955
Early in the war (for the USA). Early
wolf pack experiences. Seen through the
eyes of the senior officer (commodore, if
you will) of the four escort ships.

I really like Forester and have read most of his books but the more I
study, the less I treat him as a reliable source for "how it was".

I suspect that you have not read "The Good
Shepherd". It is not a Hornblower novel.

I have read _The Good Shepherd_. It's exhausting to read and gives a
feel for how exhausting _real_ ASW was and is.

Yes, and the commander's considerations: fuel,
depth charges on hand, distance to go, moral of
the men, enduring action for days on end, etc.

The most recent ASW campaign, in the South Atlantic during the Falkland
War indicates that even with All Mod Cons, things haven't changed much.
The ASW helos expended 31 Mk-46 torpedos "some of these hit the seabed,
but most were fired at seabed wrecks and whales."

Paul

[Alan Meyer]

... "The Good Shepherd". It is not a Hornblower novel.

Another very fine novel of anti-submarine warfare that I must have read
50 years ago is _The Cruel Sea_ by Nicholas Monsarratt. He wrote a
number of other books on this subject but I haven't seen them.

Of course there are good books on the other side:

_Sharks and Little Fish_ by Wolfgang Ott

_Iron Coffins_ by Herbert Werner

and a fine novel:
_Das Boot_ by Lothar-Günther Buchheim

Alan

[Rich Rostrom]

A more-or-less factual memoir of RN service
in the Atlantic, from the point of view of
the "other ranks":

_Heart Of Oak_, by Tristan Jones.

Utterly authentic, though I have my doubts
that he was present for the sinkings of
HOOD, BISMARCK, _and_ SCHARNHORST, _and_
saw REUBEN JANES and KEARNY shortly before
they were torpedoed, _and_ was in the
escort of PQ-17...

[c***@gmail.com]

Post by Rich Rostrom
A more-or-less factual memoir of RN service
in the Atlantic, from the point of view of
_Heart Of Oak_, by Tristan Jones.

According to Wiki, Mr. Jones joined the RN in 1946 and served 14 years.

I remember hearing about _Wayward Sailor_ by Anthony Dalton when it came out
and revealed the extent of Jones' fabrications, but I've never read it myself.

Chris Manteuffel

[news]

On Sun, 13 Apr 2014 16:27:02 -0400, Rich Rostrom

Post by Rich Rostrom
_Heart Of Oak_, by Tristan Jones.
Utterly authentic, though I have my doubts
that he was present for the sinkings of
HOOD, BISMARCK, _and_ SCHARNHORST, _and_
saw REUBEN JANES and KEARNY shortly before
they were torpedoed, _and_ was in the
escort of PQ-17...

That definitely strikes me like Sir Harry Flashman who managed to be
everywhere that was important during the Victorian era.

I have no doubt Mr. Jones might well have INTERVIEWED people that were
present at each of the above historical moments but that's a long way
from suggesting he himself was there.

[Mario]

Post by Alan Meyer
Perhaps this would have happened during the periods in which
the British
had broken the U-boat codes. I don't know how practical it
would be to route 40 individual ships, any one of which could
pick up a U-boat tail, and some of which would not have been
good security risks for exchanging
information about routing with England. But in the absence of
such routing, it's hard for me to understand how an unescorted
convoy would do better than independent sailors.

Just consider a circle 30 mi spotting radius around every ship,
that's 700 sq mi each and 28000 sq mi total

A convoy where 40 ships are 3 mi away has a radius about 10 mi
adding 30 mi spotting radius makes a 40 mi radius circle that
makes 1250 sq mi.


28000/1250 is about 20 times larger probability being spotted.

Id est, 20 times submarines needed to spot a ship.


Then, if a sub gets a lone ship, 1 torpedo used and 1 ship gone;
no ship left.
If a sub gets a convoy, all torpedoes used and 10 ships gone,
then it has to go back to base; 30 ships left.

[Scott M. Kozel]

Post by Mario
A convoy where 40 ships are 3 mi away has a radius about 10 mi

A convoy that large could be -heard- clearly inside the submarine at that distance, sound travels much better through water than it does through the atmosphere.

[ADPUF]

Post by Mario
Just consider a circle 30 mi spotting radius around every
ship, that's 700 sq mi each and 28000 sq mi total
A convoy where 40 ships are 3 mi away has a radius about 10 mi
adding 30 mi spotting radius makes a 40 mi radius circle that
makes 1250 sq mi.
28000/1250 is about 20 times larger probability being spotted.
Id est, 20 times submarines needed to spot a ship.
Then, if a sub gets a lone ship, 1 torpedo used and 1 ship
gone; no ship left.
If a sub gets a convoy, all torpedoes used and 10 ships gone,
then it has to go back to base; 30 ships left.

Is all that I wrote correct?
(in concept - numbers are less important)

[GFH]

Post by Mario
Just consider a circle 30 mi spotting radius around every ship,
that's 700 sq mi each and 28000 sq mi total.

In which war have submarines had a 'spotting
radius' of 30 mi? 53 thousand yards???

Convoys are larger than single ships. But
a fast ship was safer sailing alone. That
is why the 'Queens' sailed along.

Slow convoys got their safety by escorts
which kept u-boats underwater a lot. Yes,
surface attacks by u-boats were common.

BTW, my uncle was an engineer on tankers
during WWII. He was on three tankers which
were torpedoed. He pointed out that sinking
a tanker was hard. The oil was lighter than
water. The spectacular fires were due to
deck cargo of 55 drums of aviation gasoline,
usually on freighters. The heavier oil, like
diesel and heavier, even kerosene, does not
ignite easily.

My father was in the 'black shoe navy'
My uncle was in the 'brown shoe navy'.

GFH

[Rich Rostrom]

Post by GFH
In which war have submarines had a 'spotting
radius' of 30 mi? 53 thousand yards???

The eyes of a U-boat lookout on the top of the
conning tower were about 7 meters above the
surface.

The tops of the masts of a Liberty ship were
about 30 meters above the surface.

So max spotting range was about 29 km. Which
is less than 30 miles, but still a long way.

Post by GFH
Convoys are larger than single ships. But
a fast ship was safer sailing alone. That
is why the 'Queens' sailed along.

The Queens could make 30 knots. WHat worked
them would not work for the 90% of Allied
merchant ships that could make only 12 knots
or less.

Post by GFH
Slow convoys got their safety by escorts
which kept u-boats underwater a lot.

Even as late as March 1943, escorts couldn't
actually prevent a wolfpack from attacking
a convoy. They couldn't force U-baats to
submerge at night unless they got close.

And there were never enough escorts for all
convoys. Safety for convoys came from not
being found.

That was dependent on ASW patrol planes
keeping U-boats submerged, and on ULTRA
decrypts that gave the positions of U-boat
scouting lines.

After March 1943, the ability of Allied
ASW to sink U-boats became a decisive
factor.

[Michael Emrys]

The tops of the masts of a Liberty ship were about 30 meters above
the surface.

And I imagine their smoke plumes reached even higher and might have been
visible farther away. This would be especially true of older
coal-burning merchant ships.

Michael

[David Wilma]

One thing to remember about video and film representations
is that the narrative is constrained by time and by the imagery
available. Add to that any writer/historian's take on an event
then subtract whatever an editor deems unnecessary. Video and
film is a compelling medium, but does not always convey the
complete story.

For documentaries I often just listen to the narrative and find
I get much more information if I am not distracted by another
view of the Arizona blowing up or German soldiers on BMWs.
Some of these are very well written.

[Rich]

Post by Chris Allen
3) When the US was forced into the war, U-boats attacked US ships on US
east coast. For several months the US refused to take what the british
considered to appropriate precautions. No convoys, would not darken
ship at night, coastal towns would not dim their lights so ships were
clearly silhouetted at night. Germany called the period "the 2nd happy
days".

There has been considerable confusion and quite a bit of misinformation
over the years regarding the East Coast "blackout" regulations. The first
blackout in the U.S. at the start of the war was enacted on the West Coast,
from the Mexican to the Canadian border, at 1900 hours PST on 7 December.
However, it caused numerous problems. For one, there was no centralized
"switch" to turn off power, especially to public utilities such as street
lights. In Los Angeles, it was remarked that the 10,000+ street lights
were in different jurisdictions, with different sections on different
timers. On the East Coast, the first blackout was declared for D.C. on
13 December, and was only partly successful, for many of the same reasons. Boston tested its blackout successfully in early January and Manhattan
about the same time. However, they were focused on air raid protection and
not on coastal defense.

Part of the problem with coastal defense via blackout on the U.S. coast,
both East and West, was the size of the populations and urban areas close
to the coast. It was found early on that blacking out the port cities
did little good, because the background illumination of the hundreds of
cities and towns a few miles inland made it moot. In any case, the early
successes of Paukenschlag were in part unforeseen because it was believed
the Germans would not risk their relatively short-ranged (8,000-8,700 NM
versus 11,000 NM for contemporary U.S. subs) in such an affair, plus
there was an early breakdown in communications between the UK Submarine
Tracking Room and the USN that dissipated the warning.

As a result of Paukenschlag, discussions between the War and Navy
Department on 2 and 16 March 1942 led to the first mandated blackout on
18 April 1942. However, even that proved inadequate because of the
background illumination problem, and on 14 May 1942 the blackout was
extended further inland...and extended again in June and then August.

The worst though was the simple fact that many communities for months
either failed to observe the regulations or simply flouted them.

Post by Chris Allen
4) Eventually the US got its act together and the "2nd happy days" were
over.

The peak was basically from mid-January to late July 1942. After that
the U-Boats had sporadic successes until mid May 1943. It was all down
hill after that for the Germans.

Post by Chris Allen
5) Longterm success for the allies remained uncertain for some time. As
late as February 1943, some British staff believed they could not win.
Then in May 1943 it all "came toga]ether" for the allies and their
longterm success was assured, though they may not have realised at the time.

Long term success was never in question, although it was questioned at
the time. Two different things.

Post by Chris Allen
Now then, the video I saw recently (on You-Tube) was mainly about diving
on an unknown U-bout, sunk off US east coast. Never the less, they
"explained" some of the history. This history included an explanation
for the "2nd happy days".
They claimed that Admiral King refused to convoy ships on US coast
because he lacked suitable escort ships. "Ships in a badly defended
convoy were in more danger than ships sailing alone". I can see that
MAY be valid, but these ships still sailed with navigation lights on and
coastal towns did not "brown out".
He also claimed it was more important to escort troop ships rather than
freighters. The video demonstrated the validity of this by stating that
no troops ships were ever lost. Sounds good except that I believe these
troop shipments began much later, after the "2nd happy days" were over
(with operation Torch?).

The first major Troop Convoy from CONUS to the UK was USAT Chateau
Thierry and HMTS Strathaird with 34th Infantry Division Advance
Command Post of Headquarters Company; 133rd Infantry Regiment less
2nd and 3nd Battalions; 151st Field Artillery Battalion; det of 109th
Medical Battalion [136th Medical Regiment]; det of 109th Quartermaster Battalion; Company "A" of 109th Engineer Combat Battalion; det of
Military Police Platoon; det of 112th Engineer Combat Battalion;
10th Station Hospital; det of 63rd Signal Battalion; probably on the
order of 3,000 troops. It left New York on 15 January 1942. The second increment of the 34th Infantry Division left New York on 19 February
1942 in a 21-ship (plus escort) troop convoy. The third left 30 April
1942 in an 8-ship convoy and included the leading elements of the 5th
Infantry Division sent to Iceland. On 11 May 1942, Queen Mary left
with the bulk of the troops of the 1st Armored Division, 9,880 troops,
the remaining elements left New York in two convoys on 25 and 31 May
1942...and so on.

Any single succesful attack on any of those could have resulted in
thousands of troop deaths.

Post by Chris Allen
The video closed by claiming all the fuss about U-boats was over stated
because they only sank about 1% percent of all allied shipping.

Yep.

This post contains Long Lines.......

[Geoffrey Sinclair]

I saw a video recently that challenged what I thought was "accepted truth"
about the battle of the Atlantic.
To date I thought the "accepted truth" was
1) In the first few months of the war, U-boats gave the British very hard
time. This was largely due to British short comings, i.e lack of
organisation and suitable escort ships. The Germans referred to this
period as "the happy days"

The first few months of the war were a struggle for both sides, Germany
started the war with 57 U-boats of which 12 were considered to be
trainers. To the end of May 1940 24 were lost versus 18 new ones
built, at the start of May 1940 the fleet was at its wartime lowest point,
49, including 3 boats on trials and 15 for training.

In terms of merchant ships to end May 1940 Lloyds says around 800,000
GRT had been lost to U-boats versus around 530,000 GRT to mines, of
these around 490,000 GRT lost to U-boats and 314,000 lost to mines
were from the countries at war with Germany. There were plenty of
neutrals at the time.

So the exchange rate was around 33,300 GRT sunk per U-boat lost,
and about 90,000 GRT sunk per month.

The invasion of Norway in April 1940 curtailed the U-boat war against
commerce for a while as the U-boat were deployed to try and protect
the invasion. This is where the faults with the German magnetic
torpedoes were exposed, another fault with the contact exploder was
rectified by using the RN design, a more subtle fault was not discovered
until much later, the atmospheric pressure in the U-boat, which rises
with the length of time submerged, effected the torpedo depth setting.

Then in June 1940 the fall of France removed the French fleet and
opened up the French Atlantic ports to U-boats, in addition to around
the end of September 1940, the threat of invasion, plus the losses taken
evacuating troops from Europe, meant significantly fewer ships were
available to escort merchant ships.

Roughly the 13 months from June 1940 to June 1941 became a very
successful period, with the first happy time being considered the
summer of 1940. Around 3,156,000 GRT sunk, against 22 U-boats
lost, or around 143,500 GRT per U-boat lost and around 243,000
GRT sunk per month.

Front line strength, that is the number of U-boats available for
operations reached its lowest point for the war at 21 in February
1941, it had been in the high 20's or low 30's for most of 1941.

So on a sinkings per U-boat patrol the figures would be even
more effective, compared to the early part of the war.

2) Over the next 2 years, things improved for the British. From Ultra
they knew how U-boats were deployed. They also gained more experience in
managing convoys and more/better escort ships. For Germany, the "happy
days" were over. Never the less, Britain's long term survival was still
uncertain.

In the period July to November 1941, U-boats sank around 600,000
GRT of merchant shipping while losing 13 U-boats, or around 46,000
GRT per U-boat loss or 120,000 tons per month.

This is despite a rise in front line U-boat strength to 52 in July and 88 in
December 1941, so a major decrease in effectiveness.

In September 1941 U-boats were sent to the Mediterranean with 23
active in December 1943, or about a quarter of the operational
U-boat fleet. The opening of the Arctic convoy route initially did little
to U-boat deployments, only 2 in July 1941, rising to 5 in December.
The U-boats sent to the Mediterranean were essentially trapped there,
given the currents flowing into the Mediterranean from the Atlantic and
the defences at Gibraltar. Though some Italian submarines made it
to the Atlantic and served for a time.

In September 1939 the RN had 107 modern and 79 older destroyers,
plus 32 anti submarine ships, "escorts".

By the end of 1940 the figures were 90 modern, 71 older destroyers,
50 ex USN destroyers, 19 Hunt class, and 88 escorts.

By the end of November 1941 the figures were 86 modern, 69 older
destroyers, 48 ex USN destroyers, 41 Hunt class, and 218 escorts.
So the Germans had nominally twice the number of U-boats available
to commerce warfare in December 1941 versus the start of the war,
the RN had over 7 times the number of escorts. However some of
these were being used for other duties like coastal convoys, to guard
against the aircraft and S-boat threat.

Coastal Command had around 250 aircraft in September 1939,
200 of which were short range, basically Ansons. At the end of
1941 it had around 400 aircraft, only 18 of which were considered
short range.

In addition radar was being fitted in increasing numbers and the
centimetric sets had been around for almost a year.

So on the trends at the time the British were becoming confident
they were doing well in the battle of the Atlantic. The need for
Arctic convoys however would dilute the forces available in the
Atlantic and that was considered a problem.

While the U-boat war is largely associated with the wolfpack tactic
in fact the early part of the war had few such operations, as the
number of U-boats was low and the amount of shipping sailing
independently was high.

Clay Blair has some of the best figures on Convoy losses,
as opposed to independent sailings.

His figures for 1939 are 700 ships sailing from North America
or Sierra Leone to Britain in convoy, 5 ships lost.

In 1940 5,434 ships sailing from North America or Sierra
Leone to Britain in convoy, 133 ships lost.

In 1941 5,923 ships sailing from North America or Sierra
Leone to Britain in convoy, 153 ships lost.

During this time period 19 convoys lost 6 or more ships,
a total of 187 ships from the 19 convoys, worst hit was
SC7 with 21 ships lost, in October 1940. So these 19
actions accounted for most of the 291 ships lost from
convoys.

According to Blair ship losses to U-boats and Italian
Submarines were 1939 147 ships, 1940 520 ships,
1941 457 ships. Note this does include losses in the
Mediterranean.

Blair quotes US tenth fleet figures of North Atlantic
convoys, 169 ships lost out of 7,558 in 1942, 139
out of 9,097 in 1943, 11 out of 12,907 in 1944 and
6 out of 5,857 in 1945.

The drop in U-boat effectiveness in the second half of 1941 is down
to several factors, the main one being the British raised the minimum
speed a ship had to have before it was allowed to sail independently.
In addition the number of air and sea escorts was rising and their
effectiveness increasing even more thanks to radar and better training
and tactics.

The cracking of the U-boat code also helped the allies, though the
Germans were usually reading the RN merchant shipping code.
Diversion of so much U-boat strength to the Mediterranean also
cut the war against merchant shipping.

The USN began escorting convoys to Britain in September 1941,
changing over at a Mid Ocean Meeting Point, MOMP.

If you look at a map of where the merchant shipping losses were
occurring you can see the initial losses near Britain then moving
away and slowly moving closer to North America over the 1940
and 1941 period.

3) When the US was forced into the war, U-boats attacked US ships on US
east coast. For several months the US refused to take what the british
considered to appropriate precautions. No convoys, would not darken ship
at night, coastal towns would not dim their lights so ships were clearly
silhouetted at night. Germany called the period "the 2nd happy days".

Yes, it was a failure across the system, from the USN and the USAAF
preferring "offensive" patrols, the failure to use convoys, the failure to
enforce blackouts, the failure to turn off navigation aids, the failure to
stop the merchant ships keeping peacetime radio procedures.

The fact the U-boat codes had been changed helped them but given
they were operating as single raiders their need for radio communication
was small.

In 1942 axis submarines sank around 6,080,000 GRT, or nearly
1,500,000 more GRT than had been sunk to the end of 1941. Much
of this was off the coast of North America and the Caribbean.

4) Eventually the US got its act together and the "2nd happy days" were
over.

Sort of like the move away from the area around Britain the U-boats
were forced away from the North American coast, initially moving into
the Caribbean.

5) Longterm success for the allies remained uncertain for some time. As
late as February 1943, some British staff believed they could not win.

I have not heard of this.

The problem in March 1943 was the U-boats seemed to be able
to finally break convoys, there were so many U-boats in service they
could overwhelm the escort, Germany had just under 200 U-boats
serving in the Atlantic.

Then in May 1943 it all "came toga]ether" for the allies and their
longterm success was assured, though they may not have realised at the time.

Part of the reason there was such a strong turn around was the
release of ships from the Torch landings, creating a surge, including
the arrival in numbers of escort carriers.

Support groups could now be moved between convoys depending
on the level of threat or simply hunt U-boats without the need to
worry about protecting a convoy.

Now then, the video I saw recently (on You-Tube) was mainly about diving
on an unknown U-bout, sunk off US east coast. Never the less, they
"explained" some of the history. This history included an explanation for
the "2nd happy days".
They claimed that Admiral King refused to convoy ships on US coast because
he lacked suitable escort ships.

This is the standard defend King reason given, usually along with FDR
refused requests for more anti submarine ships, or only wanted coastal
escorts.

See below for an idea about US troop movements.

Norman Friedman in his book US destroyers, which is a design history,
notes the USN rejected the destroyer escort idea through 1940 and
1941, preferring full fleet destroyers.

Most US merchant shipping movements were along the coastal US
and Caribbean, given they were keeping out of the eastern Atlantic.

The US was certainly short of escort ships and aircraft, but the assets
available were misused.

"Ships in a badly defended convoy were
in more danger than ships sailing alone". I can see that MAY be valid,
but these ships still sailed with navigation lights on and coastal towns
did not "brown out".

Essentially all the wartime experience showed ships in a convoy
were better off, the herd immunity if nothing else, plus the presence
or assumed presence of escorts forced the attacking submarine to
be more cautious. See the Blair figures above.

It took about as much effort to find a single ship as a convoy, and
the more (groups of) ships the greater the chance of an interception.
If you have few anti submarine assets they are best defending
convoys.

He also claimed it was more important to escort troop ships rather than
freighters. The video demonstrated the validity of this by stating that
no troops ships were ever lost. Sounds good except that I believe these
troop shipments began much later, after the "2nd happy days" were over
(with operation Torch?).

There were some US troop ships lost, it depends on the definition
of troop ship.

Operation Roundup, the proposed landings in France in 1942, saw
the movement of 2 infantry and 1 armoured division to Britain and
Iceland in the first half of 1942, while the Marines at Iceland were
returned to the US.

The US had a nominal 3 divisions in the Pacific at the start of the
war against Japan, this had risen to 8 by the end of June 1942,
after losing the nominal division in the Philippines. The US
sensibly assumed the IJN could use their submarine fleet to
conduct commerce warfare in the Pacific, then relaxed the
escort requirements when it became clear the IJN was largely
using them as fleet units.

Then there were the service troops as well as Air Force etc. to
be moved.

The video closed by claiming all the fuss about U-boats was over stated
because they only sank about 1% percent of all allied shipping.

The 1% of allied shipping figure is clearly wrong, axis submarines
sank around 15,000,000 GRT of allied and neutral shipping, versus
the allied fleet being around 60,000,000 GRT at the end of the war.
So if you like 20% of shipping the allies had access to during the
war, 25% of the fleet size at the end of the war and (drum roll please)
around 50% of the UK and US sea going fleet in 1939. Of course
the latter figure ignores the sizeable contributions of countries like
Holland, Norway and Greece when they entered the war but it does
look dramatic.

It seems like the idea is to use the number of voyages, and calculate
the percentage loss versus sailings, though I really doubt there were
over 275,000 sailings.

To put it another way according to the Bomber Command War
Diaries some 3,775 Lancasters were lost during the war, or 2.36%
of sorties, or to put it yet another way 56% of the 6,712 Lancasters
officially built to the end of April 1945 were lost. One percentage
figure tends to look more dramatic than the other.

I believe the claims made on this video just don't add up. Am I right?

You are largely correct.

Geoffrey Sinclair
Remove the nb for email.