Could the Kriegsmarine IJN neutralize the US War Effort with a combined attack?

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Not true. Experienced air units were needed to sink the boats, but as I pointed out to PB this was not the key function of air assets, it was to force the boat to submerge, become a static unit as a result, and provide adbvance warning and spotting services to the offensive hunter groups and the convoys alike.

Sinkings increased in the latter half of 1942, principally at the hands of the ASV night capable units of coastal command. U-Boats typically would surface at night to recharge their batteries, in the3 belief that they could not be spotted by the air patrols (particualrly in the bay Of biscay). With ASV the allies became adept at stalking the surfaced boat and then illuminating the taerget with either starshell or Leigh Lights, for the final run in. A lot of boats were lost until the introduction of the METOX Radar detection system

The first use of ASV Radar was in 1940, but the combination of leigh Light and ASV radar was not undertaken until the latter half of 1942. Wing Commander Humphry de Verde Leigh (later OBE DFC AFC) developed the Leigh light, effectively a powerful flood light steered by the ASV radar. This allowed ASV radar equipped aircraft to search for U-boats at night. The U-boat was initially tracked by the radar with the light following the radar track but switched off. Once the returns were lost, the light would be switched on and the U-boat would be bathed in light and very vulnerable, the first successful attack was on U502 on 5th July 1942. The sudden light was often the first indication that the U-boat had been found and the Leigh light was initially very successful, particularly in the Bay of Biscay.

Metox was the German answer to the Leigh light rendering it completely ineffective. The Metox sets received the transmitted pulses from the ASV and rendered them as audible beeps. It enjoyed the usual advantage of radar detectors over radar in that the signal is direct and only had to travel one way whereas the radar has to detect the very weak reflection from the submarine.[3]. Most radars increase the number of pulses and decrease the width of the pulses when switched to a shorter range, the shorter pulse widths allow the radar to look at closer objects. The Metox exploited the fact that once the radar operator changed the range indication from 36 miles to 9 miles (15 km), the pulse repetition frequency of the radar's transmitter doubled. Radar cannot detect any reflections returned earlier than half a pulse width so when the U-boat was closer than 9 miles the operator would change to the shorter scale. If the Metox set started beeping at twice the rate, the U-boat knew that they had been detected. By the time the aircraft approached the U-boat's position enough to energise the Leigh light, the U-boat was well under the water. As a bonus, the Metox set would also provide warning in excess of visual range in daylight.

Metox was eventually countered by a version of the 10 centimetre H2S which Metox couldn't detect and once again the Leigh light forced U-boat crews to refuse to run surfaced at night. Even during the day, the U-boats were easy prey as the new radar was easily able detect the U-boat's periscope.
 
Yes and this does make the most sense. Even if it was needed to abandon BB's under construction, the USN would never do it. At that point in the war, they didn't know that BB's would not be needed to play a great role in the Pacific, they wanted to re-build the BB's after Pearl.

Not referring to the BBs, or more specifically the nearly completed BBs. There were large number sof DDs, CAs, CLs, and all manner of other ships not suited to ASW work, along with huge numbers of other ships that were years away from completion. Given the clear and immediate danger of this sub campaign on steroids, all of this effort flies in the face of the immediate needs of the country, namely small cheap ASW escorts, made ready for service within 5-6 months of laying down, and vast ly increased access for the Merchant tonnages to the vastly more efficient navy yards which at that time were almost exclusively reserved for Blue water naval construction

Had the resources IN THE USA, very true, but how to ship it overseas?


Err, not completely. The US was still a nett importer of raw materials, from various parts of the world. Without access to foreign markets and resources, the US economy, just like every other world economy suffers in terms of efficiency. The US was admittedly luckier than most, but by no means immune, or even substantially imune from the effects of a blockade.

In the historical model it did not because the Commonwealth maintained enough supplies to hold the Japanese at the Indian border. However if the Japanese are able to conquer India as well it provides enormous problems for your re-conquest of the Pacific.

This also applies to China, which almost certainly would succumb unless supported by the US. US does not have the manpower to take on the japanese army head to head. the result is a bloodbath in the pacific.

The key point is that by cutting off supplies to Russia and breaking UK control of the Indian Ocean Middle East, Germany has a good chance of eliminateing serious Soviet opposition by mid 1943.

Would the USA support 1943 operations against Japan while the European theatre collapses? I think not. Roosevelt, Stimson Marshall were all agreed on "Germany First", and in the event of a 1942 collapse of the USSR were in favor of a "suicide" attack into France to try to shift Nazi forces away from the Soviet front.

In other words, a comprehensive collapse of the grand alliance. The means to victory would dissolve if the U-Boats are not restrained from any runaway success[/QUOTE]
 

Sorry, I was not very clear, I was meaning experienced ASW naval units, as training practice were needed in ASW group operations, where a skilled flotilla leader could keep a sub "pinned" on sonar while directing the others into position to depth charge. The U-boats had also become skilled in changing direction evading DC attacks, when the hunter lost sonar contact as it moved in to DC range.


Mainly I agree with you, however there is virtually zero chance that Admiral King will agree to this in the first 5 or 6 months. About the best I could see is in mid 1942, after the US loses 4 or 5 million tons a partial re-order. Probably King would insist on completing the Iowa's, convert all building DD's to ASW, complete the CA's CL's with less than a year left, convert many newer CA hulls to CVL's, and scrap all cruisers with more than 18 - 24 months to completion.

As a practical matter, by the time the USN realizes the true scale of the problem, convinces the leadership of the drastic measures needed, tool up build the ASW DE's corvettes, any relief would only come at the end of 1942.


I was mainly referring to military resources, but as regards to food, oil mineral resources, the USA has the option, in exteme circumstances, of halting ALL shipping, and the mainland will not starve, freeze, or be in danger of invasion. The British have no choice but to keep the ships moving, or face collapse of the Empire.


There is a good chance of that happening. It's hard to predict the effect on the USSR, however it is clear that continued Allied support of the Indian Ocean theatre becomes extremely difficult, if not impossible.
 
Parsifal, I'm still waiting for you to explain why the allies would continually take huge losses without changing their tactics.

Its like your planning on the allies to basically do nothing different for months on end.
 
syscom3 said:
Parsifal, I'm still waiting for you to explain why the allies would continually take huge losses without changing their tactics.

Its like your planning on the allies to basically do nothing different for months on end.
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The huge losses would continue because in the face of a massively reorganised and enhanced assault directed on the Allied merchant fleet, your preferred response was to do nothing. The US was able to nearly lose the war when being assaulted by an average of something like 20 Boats per month attacking them, how much more shipping would be lost if the defences are spread so much thinner (over two oceans instead of just one) and with an average of someting like 70 Boats dedicated to attacking them in any given month (being about 40 German Boats and 30 Japanese). With thinner US defences, and more subs, it is inevitablel that the shipping loss rates will go up, and the sub loss rates will go down.

It was not me that proposed to do nothing in response to this threat. I postulated that against such a clear danger the allies would be more or less forced to make big changes to their deployments (for the RN in particular, but also in the use and deployment of the USN DD force). Your response to this hypothetical was that basically nothing needed to be done, in particular you totally rejected the need to halt dockyard efforts to get a blue water navy completed, in favour of getting increased MS tonnage out, and of course to increase the output of small ASW escorts out as well. This was precisely what the Brits were forced to adopt in 1940 with her capital/large warship production more or less curtailed until 1942.... In the USNs case this proved unneccesary with the historical looses, but with the enhanced U-Boat campaign being toutedor postulated here, even the US would need to bow to such pressure and temporarily curtail her Blue water strategy. You rejected that, which means that the US merchant fleet continues to be decimated, and the Allies ultimately, and quickly lose th war.

You misunderstood me. I was very much advocating a change in tactics, production, and deployment of allied resources. I took your respones to be that no change would be needed,that the problem was minimal, and it would tend to dissipate itself with time.....like it was a minor problem not needing a grat deal of attention. This i consider to be a war losing strategy......moreover, a change in tactics for the Us also requires a change in the expenditure of industrial power... they need to invest in an ASW fleet, and replace increased MS losses NOW if they are to ensure the survival of the alliance.....
 
54% of the U Boats that were submerged and robbed of their mobility permantly were sunk by ASW aircraft from Jan 42 til May 43
 
pbfoot said:
54% of the U Boats that were submerged and robbed of their mobility permantly were sunk by ASW aircraft from Jan 42 til May 43
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That's an 18 month period Pb - How many U-boats were sunk off the US east coast in the first 4 months after Pearl? - ZERO

U-85: sunk 14 April by destroyer USS Roper off Cape Hatteras, first sinking in US waters
U-352: sunk 9 May by cutter USCGC Icarus off Cape Hatteras

In the first 6 months after Pearl Harbor, despite heavy shipping losses only TWO U- boats were sunk off the US East coast!

Two more U-boats lost in June in US waters.

U-157: sunk 13 June by cutter USCGC Thetis off Havana, Cuba
U-158: sunk 30 June by Mariner aircraft (USN VP-74) west of the Bermudas

The bulk of the U-boats you quote in you "54%" were sunk from the end of 1942 - May 1943.

The Axis have a "free shot" against the Allies in the Western Atlantic for the first 6 months after "Pearl", as the US have very minimal ASW available, and Admiral King resists attempts to counter U-boat attacks.

syscom3 said:
Parsifal, I'm still waiting for you to explain why the allies would continually take huge losses without changing their tactics.

Its like your planning on the allies to basically do nothing different for months on end.
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Syscom, there will be an Allied reaction, but because of the stubborness of King the US unpreparedness, it will be several m onths befor anything can be done that will have a real effect. Besides a few U-boats sunk off the US fron April - June, the US response came after 4 - 7 months, Costal blackouts in April, convoys in May, and a total "Lock down" keeping all ships in port, in July after losses had piled up.

The responce to a much more severe attack would be quicker by a month or so, but the damage would already be done. It was also very helpful to the Axis that Admiral King had taken over command from Adm. Stark

The US is a completely different system than the British, as the lack of a central shipping board means that nobody has an accurate grasp of where the ships are and how many are lost. Ships were also free to sail where or when they wanted, unlike the British that forced all Atlantic shipping into convoys. The WWII US command lacked the "Chiefs of Staff" meetings that the British had, and also Admiral King's command did not keep track of merchant losses in a timely fashion. I don't think the US will be capable of any counter strategy for 3-4 months.

 

Parsifal, I'm not sure if that was Syscom's position or if that was his interpretation of the USN mentality.

In the hypothetical scenario we are anticipating what the most likely Allied responce would be, not what WE might do.

Your ideas generally make sense, but would not be adopted by the USN for a half year or more, at which time the damage has been done.

Also why do calculate only 40 U-boats? From Uboat.net the U-boat total seems to be about 220 at the end of 1941, if they can keep 120- 130 or so on patrol at any one time, they should be able to have 80 - 90 per month to attack shipping off the US East coast, Gulf of Mexico Caribbean. I had annticipated that the advance warning of the japanese attack allowed the Germans to arrange to send some U-boat supply ships in the Caribbean.
 
If the U boats could sink 2 a day for every day of the war they might have a chance but the Liberty ships alone were coming down the slip a that rate . The fact remains ASW aircraft were not just there to keep the subs submerged they sank the bulk of the U boats post 41 . Yes the US was slow off the draw for U boat warfare but certainly light years faster in their aquiring the tactics needed then Coastal Command
 
Hi freebird


Acknowledge that we need to look at the most likley outcome of the allies. Whilst i view the US capability in ASW at the beginning of the war to be backward, I do not consider the US leadership to be incompetetent. if faced with massive losses, they would have reacted much more quickly than they did historically. Thgis would have to be the "quid pro quo" that I spoke about eleswhere. Historically the US showed itself to be extremely adaptable, from the very start. As an example, up to pearl Harbour, the USN war stratgies were based around the battleship. There were of course advocates of carrier based strategies, but these were in the minority, and their views did not represent the policy position of the USN at the wars start. Within a month the USN had adapted its Mahanian strategies from being centred around Battleships, to being centred around carriers. When they saw just how effective carriers were, they never went back to the battleship strategy

In just the same way, if faced by a massive underwater threat, I see no reason why the US would not have adapted its strategic position to meet this alternative very quickly. Granted that it would take longer than no time to achieve certain things, specifically, the training and tactical doctrine, the equipment, and the experience, which would have taken 6 to 9 months to start to acquire, however, there are some things that they could have done more or less straight away. The most obvious is the adoption of a proper convoy system, the next is the redeployment of the fleet destroyers (although not an ideal ASW weapon, they could act as an extemporised escort, with additional DC racks and sonar, in stead of enhanced AA and Radar being the main improvements of the first months of the war. The USN could also do what the British had to do, things like quickly convert trawlers and other coastal craft to provide inadequate, but at least some form of escort. Away from the sea, they could have adopted much greater austerity measures in the civilian community, and directed the resources coming off the lines ...meaning aircraft....to ASW rather than the sharper end of the forces).

There is every possibility that the axis would sink a lot f ships, but IMO the USN could do enough from day 1 of the battle to survive. But it certainly is not a minor threat, and certainly requires more than a "business as usual approach" in order to win that battle. What i am not sure of is what the longer term effects of such a change in strategic priorities might bring. It would have delayed the offensives against the axis, but would the axis have taken advantge of that I dont know

The reason I only give the 40 additional boats to the germans is because of the limited endurance of te U-Boats. At the beginning of the war, the KM had something like 50 boats available, of which 40 or so were suited to Atlantic operations. This number remained more or less the same (with new Boats only just keeping up with losses) for about a year. Whilst the operational rate increased dramatically after the fall of france, the average daily availability in that first year of the war was about 12 Boats, as I recall. The reason for this is that whilst the endurance of a U-Boat was in the order of only 15 days, or so, as compared to those of the I-Boats, which could be as hig as 60 days in a pinch. granted, by 1942, the germans were stretching the endurance limits of their boats by the adoption of expedients that allowed them to stay at sea for about 25-30 days.... however the refit times on return to port for all Boats 9of any nationality) remained the same. It generally took about a month to turn a boat around after a patrol and ready it for sea again, to say nothing for getting the crew ready again. So this means that for any given 90 day period, the IJN Boats could spend up to 60 days at sea (Patrol-Refit), whilst the german boats would only be able to spend 30 days (Patrol-Refit-Patrol). Therfore, the German availbility out of a total force of 80 boats in 1942 is going to be about 50%, particulalry since some of those 80 are still in training.....
 
The best source on U-Boat losses that i could find whilst aay from my library resources (I am away for the weekend) was U-Boat net

U-boat losses by cause
In the following table I attempt to list all U-boat losses by type of loss. There are some duplications in the listing (i.e. boats being paid off and then either scuttled or surrendered) but this as accurate as I can make it right now. This is based on the very latest research and will probably not match older sources.

Ships 264 Includes a few losses to merchant ships
Aircraft 250 Includes all ship-based aircraft
Aircraft Ships * 37
Missing 52 See U-boats missing in Action
Air raids on ports 43 Check out this page.
Mines 35
Captured 3 U-110, U-505 and U-570

Scuttled 242 Read about Operation Regenbogen
Surrendered 155 Most scuttled in Operation Deadlight
Paid Off 37 Usually battered or "tired" boats
Accidents 25 Losses to accidents or "friendly fire"
Other (+) 7

Total 1154 (1149 individual boats)

* This does not indicate aircraft carriers, all those victories are in the "Aircraft" category. This means co-operation between aircraft (most often land-based) and escort vessels.

+ These include the 4 boats taken over by Japan in the Far East at the time of the German surrender (U-181, U-195, U-219 and U-862). This figure also includes the 2 boats U-573 and U-760 interned during the war in Spain. Finally it includes the only boat that was lost to land-based artillery, U-78 sunk by Soviet guns.

What about the missing boats?
The boats listed as missing were lost to aircraft, ships, mines and accidents. Hopefully further research will lessen this number (it has actually increased in the last years as many former claims were judged to be against something else than U-boats).

Created: 25 April, 1999. There is some slight chance that this data is not 100% accurate but it should be as accurate as possible using the best data I have right now. I will continue to work on this database and possibly edit this page somewhat.
 
The most probable course of events would be the following:

In the Atlantic:
1) The KM would run amok and inflict punishing losses on the allies for a month or so.
2) The losses would diminish quickly simply because of the "facts on the ground". Untill the ships could sail under escort, they wouldn't be sailing at all.
3) The first allied counter measures would be for the AAF to provide daytime patrol and escorts. This would blunt (but not eliminate) the daytime threat from the U-Boats.
4) Within 2 months, the existing escorts of the USN would all be equipped with adequate (meaning minimally acceptable) ASW gear, which further would reduce losses.

My point - The allies always showed the capacity to quickly change strategy and tactics. Don't assume that just because they were going to get their ass's kicked for a month or two, that they would continue to bend over for the KM.

In the Pacific:
1) The reality of the logistics of supporting the forces holding onto the pacific islands along the US-Aussie lines of communication is far simpler than that of supporting forces in the ETO. The forces on the islands were essentially light infantry battalions (or brigades) which didn't have the logisitics burdens as a full up regular infantry division. It wouldnt be that difficult for the navy to get a cargo ship to these atolls once a month to resupply them.

2) The IJN sub force never had the competency as the KM and as events proved and were more easily blunted. They were far fewer in numbers, had a far more difficult logistics issue of support, and were tracked with a good degree of accuracy through ULTRA.

As for ship building:
No doubt that escorts vessels would get higher priority, but it wouldn't be at the expense of the carrier or light cruiser programs. They were well along in construction, and it would take too much time and effort to stop them and convert over to building DD's and DE's. Instead, more materials would be made available to complete (faster) the DD's already under construction. As for the smaller ships .... the existing shipyards that were inland, would build them first, before building the amphib vessels.
 
I see that the response is basically "more of the same", namely, that a u-boat campaign four times the size and capability over the historical was "no big deal" and "nothing to worry about"!!!!!!!!!!

There are holes in the response allover the place, but to name just few....

The costs to maintain a single division in the pacific, was, on average, about nine times that for the cost of maintaining a division in europe. the costs of even a modest holding operation in the pacific are enormous. historically the campaign at guadacanal pushed the abilities of the Allied Merchant ,Marines to the breaking point. There were virtually no reserves for the allies without jeopodising or risking the integrity of the alliance itself, so unless ther is a wholesale withdrawal from somewhere, in 1942, then something or all of the allied stucture is going to break. By opting to maintain the offensive in the central and southern pacific (the least important of all the theatres of operation then being faced by the allies), then something really important is going to break, like China, Russia, britain or India.

Witholding the ships (presumably from the main trade routes) from sailing is just not an option, or at least it is an option that leads straight to the bottom for the allies. There are less than 3 months reserves of oil in britain for a start. The world economy, on which all the hopes of the allies rest, is anchored completely on the continued movement of shipping. You just cannot say "oh we will stop the movement of shipping, that will solve the problem" That would lead to the rapid political, social and economic collapse of nearly all the western world, including that of the US. Continued mercantile trade was essential. not just desirable....if it had ben possible to do that, the British would have closed down all but the atlantic run years before that...

I agree that if re-equipping and retraining the USN Destroyer force for ASW work had been a priority, it would have helped. Learning how to use it and work as effective teams is another matter. if you lack quality, you have to try, as best you can, to compensate for that lack of ability by pouring in the numbers. And the only place you can do that is by stripping out your pacific fleet of nearly every ASW platform that it possesses. That means no carrier operations, no distant force projection, and a big respite for the japanese.


I do agree basically with your points 3 and 4, they point to the road to winning. however, i cannot help but detect that you see achieving this outcome as a relatively easy and quick capability to achieve. If so, you could not be more mistaken. it would take a huge investment of manpower, resources and technique learning for the US to achieve this, not a couple of weeks or months.

I agree also that the strong points of the allies was their adaptability, but this should not be measured in defeating a U-Boat offensive of this kind in a matter of weeks or months, rather at least a year in my opinion. In that time the allies have to continue to tough it out, divert resources to shipbuilding, and pull back from areas where they dont need to be.


The flaw in this hypothetical is its assumption that the Germans and the japanese would recognize tonnage losses as a war winning strategy. I am the first to concede tht, and have repeatedly criticised it as unrealistic to expect (particularly the Japanese). however, on the assumption that they could somehow be brought around to see this as a possible strategy, I see it as a huge threat to allied survival, and one that needs more than just a passing drawing of breath . It would have needed a diversion of a massive effort (which could only be provided by the US)

Your assumption about the IJN subs are just not correct. When dedicated to tonnage attacks, they achieved sink rates comparable to the U-Boats (on a per sortie basis) and in 1942 were not significantly more vulnerable than u-boats. they took greater losses later, because they continued to be used to attack heavily defended targets, whilst the Ultra advantage you talk about really only affected I-Boats being used on supply runs. I-Boats being used to atack shipping actully suffered very low attrition ratessimply not that vulnerable whilst so engaged. Japanese I-boats did have some technological weaknesses (as well a some rathe sloppy evasive techniques), but these were not a significant factor until the allies learnt how to find and attack them, and possessed the sufficient numbers of escorts in order to prosecute such attacks effectively 9generally a ratio of about 6:1 escort to U-Boat was needed.

By continuing with the carrier and Light cruiser programs (and those later BBs as well), you are diverting the limited manpower at the US disposal away from manning of the vital defences. I think everyone here is in basic agreement, that time is of the essence if the US is to save itself and that of its allies. Every trained man has to go into the small ships, and every inch of dockyard capacity has to be diverted into the "small end of town" if the allies are going to emerge with th least amount of damage.

Fighting a two front war for the USN was its worst nightmare, and something it never really was forced to do.
 
parsifal said:
Acknowledge that we need to look at the most likley outcome of the Allies. Whilst i view the US capability in ASW at the beginning of the war to be backward, I do not consider the US leadership to be incompetetent.
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"Incompetent" is a little strong, but "weak" would be more accurate.

Considering King's handling of the submarine threat, and Stimson's Marshall's adamant insisting on a landing in France in 1942, {Sledgehammer Imperator}, there was not anyone in the top echelon with a good understanding of modern war or a solid plan to fight the war.


The leadership of the USN was concerned with "warships", it was not overly worried about cargo ships, that is the difference


Mainly correct, the real question is how much damage can the Axis do in the first 6 months before some kind of equilibrium is reached


Again you are considering "could have", not what would have been most likely, or even at all probable given the USN leadership at the time. The idea of convoys, coastal blackouts, using auxilliary ASW ships patrol aircraft was suggested to the USN and Admiral King in the first few months several times while losses were becoming serious, and was absolutely rejected every time! These measures were finally grudgingly adopted after 6 - 7 months. A much heavier loss might force the US to do this perhaps 2 months earlier, but not before about 3 - 4 months had gone by, at the earliest.


Business as usual is exactly what the USN will do in the first few months. And yes, the USN will survive, operations will just be set back a few months. The real damage will be to the British Merchant Marine, which cannot keep up with sinkings, and cannot stop sailings without isolating many overseas troops.

parsifal said:
The reason I only give the 40 additional boats to the germans is because of the limited endurance of te U-Boats. At the beginning of the war, the KM had something like 50 boats available, of which 40 or so were suited to Atlantic operations.
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The Germans had 244 U-boats in Dec 1941 according to Uboat.net.

The Germans comissioned 312 U-boats from 1935 - 1941, of which 68 were sunk in that period. Germany is producing 20 new U-boats/month at this time

So at the end of 1941 Germany had 203 U-boats {Type VII/IX} plus a further 41 coastal boats {type II} If only 50% of these are available for patrol in any given month, that gives 122 U-boats.....

uboat.net - The U-boat War 1939-1945

U-boat production:
1935 (14)
1936 (21)
1937 (1)
1938 (9)
1939 (18)
1940 (50)
1941 (199)
1942 (237)
1943 (284)
1944 (229)
1945 (91)


Total: 1153




They had 45 boats when war broke out, most of which were only coastal boats.

parsifal said:
Therfore, the German availbility out of a total force of in 1942 is going to be about 50%
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Out of 244 boats this would be 122....

Seems a reasonable estimate, however for a planned "special occasion" {ie massive U-boat attack after "Pearl"} they could probably have 65% - 70% ready to go, then drop down to ~ 50% in following months. Another thing to consider is that with a few months advance warning, not only could Doenitz have all of his U-boats in position outside the ports on "Pearl + 1", but could have some neutral freighters in position in French or Spanish ports in the Caribbean West Africa, to re-supply the U-boats without having to sail back to Germany. Since there would be very few U-boats damaged by the weak patrol ASW in the first few months, the U-boats should mainly need just food, fuel more torps, not major repairs.
 
syscom3 said:
The most probable course of events would be the following:

In the Atlantic:
1) The KM would run amok and inflict punishing losses on the allies for a month or so.
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The British should have the faster response, as the British Shipping board keeps track of all ships, the Chiefs of Staff are already focused on the problem and will not delay in action.

I would think that it would take about 4 weeks of data on ships sunk, and the British Admiralty CoS would take action within 1 - 2 weeks. Then allow for 2 more weeks for actions to be carried out, as it takes time for orders to get to ships already at sea, for aircraft escorts to be transferred etc. So the total should be 6 - 8 weeks for the British.

I would allow ~ 1 extra month for sunk ships to be tallied and Adm King informed. {no central clearing house for shipping - must wait for scattered reports from all ports of overdue ships}

Then I would allow ~ 1 more month as King vetoes corrective measures until the crisis becomes unavoidable.

So about 3.5 - 4 months for the US to recognise the problem, decide on action, and relay instructions to all units. On the + side the US is less vulnerable than the British, huge losses can be rebuilt with production, and there is no looming "calamity" for the US, unlike the British.


syscom3 said:
2) The losses would diminish quickly simply because of the "facts on the ground". Untill the ships could sail under escort, they wouldn't be sailing at all.
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Agreed, this would be the short term solution. After about 4 months the US would probably resort to only sailing heavily escorted convoys to vital outposts, Iceland, Bermuda, Hawaii, Australia, Palmyra Johnson etc.

However productivity would suffer without rubber, bauxite, tin, chromium, manganese etc. that come from South America Africa.

Also the buildup in the ETO counter-attacks in the Pacific would be delayed

syscom3 said:
3) The first allied counter measures would be for the AAF to provide daytime patrol and escorts. This would blunt (but not eliminate) the daytime threat from the U-Boats.
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Agreed, after about 4 months I could see this to help. Again, part of the delay would be resistance from the Air Force to switching bombers to ASW patrol. {same problem from Bomber Command!}

syscom3 said:
4) Within 2 months, the existing escorts of the USN would all be equipped with adequate (meaning minimally acceptable) ASW gear, which further would reduce losses.
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I think your estimate is a few months too optimistic. There are already about 20 older DD's in the shipyards awaiting conversion to ASW, but there is a delay getting space ASW equipment in the first few months.

syscom3 said:
My point - The allies always showed the capacity to quickly change strategy and tactics. Don't assume that just because they were going to get their ass's kicked for a month or two, that they would continue to bend over for the KM.
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Yes, again I largely agree with you, the KM IJN need to do the maximum damage in the first 4 - 6 months, before targets become more difficult to sink


I think you are correct, the paranoia at the time means that re-inforcing the Pacific bases is top priority to meet an {expected} Japanese attack.

The downside is that the support sent to Australia SE Asia would suffer.


ULTRA? Do you mean Magic? Actually I don't see the IJN using more than about 25% of its boats in US waters, as a bunch of sinkings in the first few months will hamper US shipping by delays, convoys, caution. The main damage the IJN would cause is in SE Asia Indian Ocean, where the British have very little ASW to spare from the Atlantic, and where they cannot suspend shipping except under extreme circumstances.


Yes that makes sense, in any event there is no way that King would cancel most BB's CA's Cv's anyways
 
Quoted...

 
Been away for nearly three weeks guys, but Im back now. Intersting discussions by all. I should re-start the discussion by saying that there is no "right" answer to this sort of discussion. its a question of deducing likley outcomes, and likley reactions.

With regard to the very detailed and excellent accounting of the U-Boat fleet, by nikademus, I would make only one comment really. Type VIIs were used in the Gul of mexico, from a very early start in the campaign. by accepting quite appalling living arrangements, and providing additioanl fuel tanks (later), they were able to achieve patrol times of about 9 days in the gulf with their Type VIIs.

The range and endurance of the Type VII was extended progressively as the war progressed, At the beginning of the war, its range was typically quoted as about 5000 miles, and about 20 days. As the battle of the Atlantic moved further out into the Atlantic, the germans found it necessary to adopt various measures, some relating to operational usage, some to technological changes to the design (mostly adding more fuel tanks to the design no easy excercise in a CG senitive piece of equipment like a submarine. By the time of the attacks on the US weat Coast and the gulf were implemented, many Type VIIs were achiving Patrol times of close to 35-40 days, and an effective operation radius of 6-8000 nm. But unlike the assertions by soren in that other thread, ther was not much room left to se these subs as transports if they were used to the limits of their endurance.
 
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