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

[Freebird]

If the Axis had made joint plans for an attack on the USA Allies, involving submarines, commandos and covert operations to begin at the same time as the Pearl Harbour attack, could it have succeeded?

1.) The U-boat war

Some facts to consider, it was not until 5 weeks after "Pearl harbor" that Adm. Donitz's operation "Drumbeat" began with the actions of just 5 five submarines off the US East coast, but these were responsible for huge losses. If the Germans had 25 - 30 boats on station at the time of Pearl Harbor, and the Japanese had stationed most of their 63 available long-range boats on the US West Coast or shipping routes, the Axis should have been able to destroy at least 3 or 4 times as much Allied shipping as they did. The Allies lost over 6 million tons in the first year, even losing double that number would have been devastating.

(Quotes from Wikipedia)

Each U-boat made routine signals on exiting the Bay of Biscay, which were picked up by the British and plotted in Rodger Winn's London Sub Tracking Room, cabled an early warning to the Royal Canadian Navy. Working on the slimmest of evidence, Winn correctly deduced the target area and passed a detailed warning to Admiral Ernest J. King in the USA of a "heavy concentration of U-boats off the North American seaboard". Rear-Admiral Frank Leighton of the US Combined Operations and Intelligence Center then informed the responsible area commanders, but little or nothing was done.

The primary target area was the "North Atlantic Coastal Frontier", commanded by Rear-Admiral Adolphus Andrews and covering the area from Maine to North Carolina. Andrews had practically no modern forces to work with: on the water he commanded seven Coast Guard cutters, four converted yachts, three 1919-vintage patrol boats, two gunboats dating to 1905, and four wooden submarine chasers. About 100 aircraft were available, but these were short-range models only suitable for training. As a consequence of the traditionally antagonistic relationship between the US Navy and the USAF, all larger aircraft remained under Air Force control, and in any case the Air Force was neither trained nor equipped for anti-submarine work.

British experience in the first two years of World War II, confirmed that ships sailing in convoy;with or without escort; were far safer than ships sailing alone. British recommendations were that merchant ships should avoid obvious standard routings wherever possible; navigational markers, lighthouses, and other aids to the enemy should be removed, and a strict coastal Blackout (or at least a "brownout") enforced. In addition, any available air and sea forces should perform daylight patrols to restrict the u-boats' flexibility.

None of this was attempted. Coastal shipping continued to sail along marked routes and burn normal steaming lights. On 12 January 1942 Admiral Andrews was warned that three or four U-boats were about to commence operations against coastal shipping, but refused to institute a convoy system on the grounds that this would only provide the U-boats with more targets.

Despite the urgent need for action, little was done to try to combat the u-boats. The USN was desperately short of specialised anti-submarine vessels. The destroyers that were available remained inactive in port, even while freighters and tankers were being sunk in coastal waters. At least 25 Atlantic Convoy Escort Command Destroyers had been recalled to the US east coast at the time of the first attacks, including seven at anchor in New York Harbour.

Considering the almost total lack of preparation, and the fact that it took 6 - 10 months for the Allies to respond with Convoys anti-sub measures (the first U-boat on the US East coast was not sunk until April), it's hard to see what would prevent the Axis from wiping out the majority of Allies shipping in the first year

 

[Freebird]

There are several threads dealing with Submarines shipping, I'm going to combine some of the ideas together.

From "How not to use submarines"

Its interesting that with all the interest in the Pacific war , and the IJN, one reads and hears so little about the IJN submarine force. They started the war with the largest submarine force in the world both in numbers and diversity. Many of their boat designs were very large with incredible ranges, perfect for the Pacific. They had several terrific torpedo designs. One of which, the Long Lance, was the best torpedo in the war. But they also had a very good electric design.

While they had some early success the IJN boats just didn't do a whole lot in the war. The few American capitol ships they sunk and damaged just didn't mean much in the big picture as American shipbuilding Industry kicked in.

The question then is "why didn't the IJN deploy their submarines in a manner that would more influence the war"? History should have taught them that the submarine was far more effective as a weapon against ocean commerce then as a weapon against capitol warships. IJN boats 184 enemy merchant ships, compared to German U-boats sinking 2,840, Yank boats sinking 1,079, Brits boats 493.

Could things have turned out differently if the IJN submarine force used different tactics?

Would it have changed the war? I dont know but I do know our commerce fleet was heavily stressed in the first few years of war by the U-boats. That, and the Pacific was light on DDs due to the Atlantic U-boat threat.

From "Which submarine was the better one?"

Simple fact is that in 1942 alone the Kriegmarine sunk more enemy shipping than the USN subs in the entire war; another simple fact is that the Allies could just endure that because the immense shipbuilding capacity the US had.

From "Did the US save Europe?"

Suppose the Japanese had destroyed the fuel storage at Pearl the maintainance facilities there too?

And if they had used their submarines to sink US shipping in the Pacific?

If you are going to hypothesize that, you may as well throw in catching the carriers.

At the most, the war would have been prolonged. Japan never wanted to conquer the US. they wanted to pursue their Asian empire building w/o us butting in.

Industrial might would prevail in the end....

Could the German U-boats IJN subs have sunk 2 or 3 times as much Allied shipping in 1941-1942?

Does anybody have an argument why they couldn't?

If they did sink Allied merchants at 2 or 3 times historical values, how would the Allies react?

 

[Soren]

My opinion is yes it could've succeeded. But Stalingrad had to be taken at some point and with it the USSR, to secure the resources necessary, but that wouldn't have been a problem once Stalingrad was conquered.

Had the German troops been equipped with winterclothes then Stalingrad would've fallen quickly, and any Soviet attempt at a pincer movement would've been made completely impossible. As it was without the winterclothing 60% of army group center was off the frontline just trying to get through the winter, while the last 40% were fighting at Stalingrad against Soviet forces outnumbering them 10 to 1.

So give the German troops their winterclothing in 41 to 42, then the USSR would've been defeated swiftly.

As for the U-boat scenario, it is very plausible if the Japanese let themsselves be indoctrinated in German U-boat tactics.

 

[Freebird]

Soren I'm not sure I can agree with you about the Germans winning at Stalingrad if they only had winter clothes, I think they need to be in a much better position vs. the UK US. Germany WOULD have to beat the USSR, thats for sure. But lets not jump ahead too fast, the situation on the ground would depend on what happens in the rest of the ETO.

The British were at the point of cancelling operations in the Far East in 1943 due to the "British Import Crisis", from the 5 million UK tons lost in the first 15 months. If for example they lost 6 or 8 million tons in the first 6 months of the war, could they keep up supplies to the Desert Army? Not unless they have some other option. And if the US has lost 4 - 6 million tons by Nov 1942, they can't keep operations going in the Pacific do "Torch" as well.

If the Germans were still in secure N. Africa, they could have 150,000 - 200,000 more troops in Russia. Now this would make a huge difference at Stalingrad.

Also, with the shipping situation going from "strained" in 1942 to "extreme crisis", would the Allies be able to send anything to Russia at all in 1942?

 

[Freebird]

As for the U-boat scenario, it is very plausible if the Japanese let themselves be indoctrinated in German U-boat tactics.

Ok I'll set out the scenario and see what people think.

1. The Japanese take Germany's advice, they send out all 63 of their subs to be ready the minute bombs drop at "Pearl Harbor", they target shipping at all of the major Allied ports in the Pacific Indian Ocean.

The IJN had the subs to create all sorts of problems for the US it was their approach to using them that was a missed oppertunity. They had the range to attack almost anywhere on the US West coast. This alone would have caused the US to spread their forces across half the Pacific, leaving weak spots.
The Japanese also had enough submarines to launch co-odrinated attacks on convoys using similar wolf pack tactics. There is a lot of ocean between the US and the pacific bases and it could have been used to effect.
A small point about the Japanese using submarines to resupply the army bases on the islands. The IJA had their own submarines for resupply, hard to believe but true.
Also the Japanese subs could dive quite quickly the earlier ones were a little slow but considering their size it was quite good and the later ones were very handy.
As for the diving depth, no submarines could match the Germans in this area so there is no shame in not matching them.

As for IJN wolf packs, I would have a "team" of 3 or more boats stationed in the following area's to tie up US escorts:

Between Hawaii and The US Mainland

Off of Baja California

Southeast of Hawaii extending to the French possessions

Near the Panama Canal

Syscom in late 1941 there is not even really much need to use "wolf packs", which were developed by Donitz to try to mass attack and "overload" protected convoys.

The IJN should send 2 or 3 subs to lurk outside all of the major pacific ports, in the Fall of '41 all of the merchant ships were unescorted in the Pacific/Indian Ocean, and ASW capabilitys were almost zero.

Of the 63 Japanese Ocean-going subs they could send out,
3 subs to each of the following:

San Diego
San Fransisco
Los Angeles
Seattle
Sydney, Aus.
Pacific entrance to Panama Canal
Aden the approach to the Red Sea

And 2 subs to each of the following:

Hawaiian Islands
Portland, Or.
Brisbane, Aus.
Perth, Aus.
Melbourne, Aus.
Auckland, N.Z.
Wellington, N.Z.
Calcutta, In.
Bombay, In.
Karachi, Pak.
Mombassa/Zanzibar, Africa
Durban/Port Elizabeth, Africa
Cape Town, S.A.
Suva, Fiji
Batavia, Java
Borneo
New Caledonia
Rangoon, Burma
Ceylon
Singapore
Straights of Hormuz (Persian Gulf)

 

[Freebird]

If you are going to hypothesize that, you may as well throw in catching the carriers.

Why not, better to consider the "worst case scenario"

2. The Japanese attack "Pearl harbor" as they originally planned, which was if negotiations did not succeed, they planned to attack at the end of October. (Scary monsters come out on Halloween? )

So they attack at the end of Oct, they catch all 3 US Pacific Carriers in port and sink them. Because Nagumo is not worried about the US carriers surprising him, he sends in a third, fourth fifth wave, destroying the Oil tanks, Sub base, repair shops, and destroys 24 destroyers 5 cruisers and badly damages the rest (5 DD 3 CA)

3. The Germans have been warned about the attack by the Japanese, so they have 40 - 50 U-boats waiting in the US West Coast Caribbean ports ready to commence operations. They have also bullied the Vichy French into allowing them the use of Martinique other ports for supply.

4. Nazi Germany does not declare war on the America, and the US Congress adopts a "Pacific First" strategy, although they will still send some munitions supplies to the UK and Russia (if there are any ships to carry them on....)

In this scenario I can't see the Allies losing any less than 7 - 10 million tons in the first 6 months, and another 4 - 8 in months 7 - 12. There are just too many unprotected ships, and it will take time to get them to safe ports or in convoys.

 

[Soren]

Freebird,

With the last 60% of Army Group Center the Germans would've taken Stalingrad, there's no doubt about that, the 40% actually there already achieved to capture 90% of the city before winter set in. Now if the KM in addition to winterclothing being shipped by the OKW could occupy the USN with the help of the Japanese in Pacific then there would suddenly be a whole lot of men available in the east - atleast another 650,000 to 700,000.

With the USSR defeated the Germans could comfortably venture into a prolonged war in the pacific as-well, but isolating Britain would still be important if an invasion was to be considered.

With unlimited resources as would be present with the capture of the USSR the Type XXI could be sent into service already by late 1943, and with that the Antlantic would've been secured.

As to your worst case scenario, I agree. If the Germans alone had been warned by the Japanese of the attack at Pealr Harbour and placed 40 - 50 U-boats to hunt down sink the US carrier fleet emmidiately after the attack (In this case the IJN doesn't sink them) it would've spelled no less than a disaster for the USN. The Japanese would suddenly have complete naval air-superiority over the pacific. The addition of the German KM in the Pacific would've indeed been a nightmarish situation to be facing for US .

 

[Glider]

Had the Germans and Japanese co operated and co ordinated their attack I have no doubt that they would have inflicted considerable losses to the allied vessels over and above the losses incurred.
However the allies would have responded differently and introduced convoys much sooner than they did off the USA coast. Losses of that size would have put ASW at the top of the Allied priority list.
Could the Japanese and Germans sustained that type of attack. Probably yes but at a reduced rate, could they have won? probably not given the technical resources available to both sides.

I am afraid that the Type XXI could not have been introduced into into service during 1943, the preliminary design wasn't finished until mid 1943. Interestingly the Japanese were ahead of the Germans in this area with a prototype high speed underwater submarine based on a significant increase in in battery power and streamlining in operation in 1939. Fortunately for the allies, the Japanese didn't follow this up until late 1944. So if anyone could have had a true submarine in 1943, it would have been the Japanese.

 

[Freebird]

Had the Germans and Japanese co operated and co ordinated their attack I have no doubt that they would have inflicted considerable losses to the allied vessels over and above the losses incurred.
However the allies would have responded differently and introduced convoys much sooner than they did off the USA coast.

Glider the problem is that the British were hard pressed to keep the convoy escorts in the North Atlantic in 1942, the USA had very little available to help with this job, they could not introduce convoys even if they wanted to. Remember it takes not only ships, (DD, DE, sloops etc) but they needed ASW equipment (Sonar, Hedgehog) and trained crew. Even after Adm. King finally agreed to put in convoys, it still took a few more months to put it all in place. And we are only talking US East Coast Caribbean here. Imagine if the Allies had to do this on the US West coast, the S. Pacific, Indian Ocean, African, Australian ports as well. The alternative is that all the ships would be stuck in port because there is no escort available. (which is what actually happened in summer 1942 on the US East coast)

Losses of that size would have put ASW at the top of the Allied priority list.
Could the Japanese and Germans sustained that type of attack. Probably yes but at a reduced rate, could they have won? probably not given the technical resources available to both sides.

For example if the last two months of 1941 the Allies lose 4 - 5 million tons worldwide. In January the Allied governments go into crisis mode, but what can they do? The US must continue to supply Hawaii, Australia the outposts at Midway, American Samoa, Tonga, NZ, etc. The British must continue to send supplies to Egypt, Malta, India, Burma, Malaya, Australia others. The US UK might lose another 4 - 5 million tons in the first quarter of 1942.

The "British Import Crisis" in March 1943 resulted after the British lost 5.1 million tons in the first 15 months after Pearl Harbour, but they built only 2.2 million tons in that time. Nevertheless, losing less than 3 million net put us into crisis mode

HyperWar: British War Economy [Chapter XIV]

British Import Crisis

I'm afraid that the loss of so much tonnage would mean abandoning the Far East (Malaya Burma), or Egypt, or even both. With the USA losing so much of its fleet, it would be in no position to help out, as it did historically in 1943

 

[Soren]

Glider,

Regarding the Type XXI, it could like I said have been sent into service by late 1943 to early 1944. As it was the boat was already being constructed in 1943.

Probably yes but at a reduced rate, could they have won? probably not given the technical resources available to both sides.

Technical resources ? Like what ?

I strongly believe they could've won the Pacific, esp. with the Japanese employing German U-boat tactics, and with the help of the KM U-boats the USN wouldn't stand much chance. There'd litterally be swarming with subs in the Pacific and the IJN would make sure the airspace was clear.

Also I think that a close co-operation in the Pacific would've lead to larger exchanges of technology between the two nations, something which would've undoubtedly been of large benefit to Japan. If the Japanese had started building AFV's a/c like the Germans it would've been all over for the Allies.

 

[plan_D]

Would the German U-boats be supplied from Japanese bases or German ones? The trip to the Pacific from Brest is a long way; I see the only option being Japanese supply bases in the Pacific. If that's the case, would the Japanese be able to keep those bases supplied from Japan - after all, the supply situation would cause greater demand as they would now have two submarine fleets in operation.
I'm certainly no expert on the Pacific submarine war, but weren't the Japanese submarines in the fleet? When the fleet wasn't in operations, nor were the submarines - correct? If that's so, which it may not be, wouldn't the Japanese supply situation be worsened if they took up the (excellent) submarine wolfpack tactics of the Germans?

Soren, I don't believe the Japanese would have done any good with Panthers or Tigers. The only real benefits would be the Pz.kpfw III, Pz.Kpfw IV, Sd.Kfz 251 and possibly a few SPGs. The war in the Pacific wasn't really an armour war, more infantry. The only real benefit in aircraft design (in my opinion) would be a small number of Bf 109s for home defence, German aircraft range was too short for Pacific and CBI operations.

 

[syscom3]

Why would Japan want to build mechanized forces?

They were short of oil, short of high quality armor steel and short of shipping to keep things running.

And then where were you going to use them?

While the concept of having IJN U-Boats run amok in the Pacific is interesting, remember the following:

1) The Pacific is a huge place in which to route convoys.
2) The IJN never did have the forward bases in which to sustain operations. Look at the distance from Truk and Eniwetok to the west coast of America. Just getting from their bases to there would take a combined month or two off of their missions. (Similar to the USN sorties from Midway to the Japanese home Islands). And the facilities at these bases was never more than enough to do simple repairs and outfitting.
3) The IJN sub force was always prone to being located and sunk. Once the escorts had radar, the subs would be having a tough time to attack with impunity.
4) Dont underestimate the ability of the IJN command structure to muck things up.

 

[plan_D]

I think the Japanese would have benefited from the German Pz.Kpfw III and IV at the very least; I recognise that most of the PTO and CBI was fought in jungle conditions but there was armoured conflict. The presence of effective armour would have been most felt in China.

I'm pretty sure that we're all aware of the Japanese Tiger and Panther - a silly idea in my opinion, far too big for the enclosed spaces the Japanese Army would be fighting in.

 

[Freebird]

Would the German U-boats be supplied from Japanese bases or German ones? The trip to the Pacific from Brest is a long way; I see the only option being Japanese supply bases in the Pacific. If that's the case, would the Japanese be able to keep those bases supplied from Japan - after all, the supply situation would cause greater demand as they would now have two submarine fleets in operation.

Plan D, the Japanese had the longest and biggest submarines of anyone, including the Germans, so they could operate anywhere in the Pacific or Indian Ocean from Rabaul, Truk, Singapore or even right from Japan. The Germans would operate where they did historicaly, except that they would be in place off the US ports right after the Pearl Harbor attack, instead of waiting 5 weeks to go into action. The Germans aslo re-fueled somewhat chandestinly from the Canary Islands, Azores and maybe also the French ports in the Caribbean Africa.

I'm certainly no expert on the Pacific submarine war, but weren't the Japanese submarines in the fleet? When the fleet wasn't in operations, nor were the submarines - correct? If that's so, which it may not be, wouldn't the Japanese supply situation be worsened if they took up the (excellent) submarine wolfpack tactics of the Germans?

The IJN submarines were very poorly used, (see quotes from Rich Glider) they were mostly "fleet aux. boats" waiting for weeks to try to hit a US Carrier, or carrying supplies. What the Japanese didn't realize is it's easier to put an Allied task force out of action by cutting off its supplies than trying to sink carriers.

P D, I think the Axis strategy would be to choke off the supplies going to Egypt, Burma India, and then they would conquer all of Asia

 

[plan_D]

Even with the long range of the Japanese submarine, it would be ideal to have a forward operating base to reduce the turnaround time after every operation. After all, long range doesn't reduce travel time - moving from Hawaii to Japan, or even Rabaul takes some time. How large was the Japanese submarine fleet in comparison the German fleet ? It's a difficult task maintaining a blockade, the question is whether the Japanese and Germans would have enough to maintain a constant blockade all year on every route throughout the Allied terrorities.

I was going by Soren's idea of Germans operating in the Pacific. The U-boats historical bases of operations wouldn't be good enough for such an adventure. They would have to operate from bases in the Pacific - which would increase the pressure on the Japanese supply system.
And as I said before, if the Japanese are using their submarines like the Germans - then their supply demand would be larger thus stretching Japanese supplies even more.

 

[Freebird]

Why would Japan want to build mechanized forces?

They were short of oil, short of high quality armor steel and short of shipping to keep things running.

And then where were you going to use them?

While the concept of having IJN U-Boats run amok in the Pacific is interesting, remember the following:

1) The Pacific is a huge place in which to route convoys.

They would mainly wait in harbour approaches, around major ports like Sydney, Calcutta, Auckland, Melbourne, Durban, Batavia, Bombay etc.

2) The IJN never did have the forward bases in which to sustain operations. Look at the distance from Truk and Eniwetok to the west coast of America. Just getting from their bases to there would take a combined month or two off of their missions. (Similar to the USN sorties from Midway to the Japanese home Islands). And the facilities at these bases was never more than enough to do simple repairs and outfitting.

Syscom, once the Japanese have Singapore (Magnificent base kindly built equipped by the British taxpayer! ) It is centrally located to threaten Burma, India, Java, Australia. The Japanese also had a plan to buils a sub base in Madegascar.

3) The IJN sub force was always prone to being located and sunk. Once the escorts had radar, the subs would be having a tough time to attack with impunity.

The US Britain have their hands full in the Atlantic US West Coast, it would take 8 - 12 months minimum to institute convoys strong ASW in Australia Indian Ocean.

4) Dont underestimate the ability of the IJN command structure to muck things up.

Thats the only thing that might save us....

 

[Freebird]

Even with the long range of the Japanese submarine, it would be ideal to have a forward operating base to reduce the turnaround time after every operation. After all, long range doesn't reduce travel time - moving from Hawaii to Japan, or even Rabaul takes some time. How large was the Japanese submarine fleet in comparison the German fleet?

In the fall of 1941, (Pearl Harbour) the Japanese have 63 long range boats, the Germans had about 100

It's a difficult task maintaining a blockade, the question is whether the Japanese and Germans would have enough to maintain a constant blockade all year on every route throughout the Allied terrorities.

Actually, its harder on the Allies. In 1942 the Axis have submarines patrolling the weakly defended Pacific Indian ports, sinking targets of oppertunity. Meanwhile the Allied cargo fleets are stuck in port, because of a lack of escorts.

I was going by Soren's idea of Germans operating in the Pacific. The U-boats historical bases of operations wouldn't be good enough for such an adventure. They would have to operate from bases in the Pacific - which would increase the pressure on the Japanese supply system.
And as I said before, if the Japanese are using their submarines like the Germans - then their supply demand would be larger thus stretching Japanese supplies even more.

Plan D, I think when Soren said "with the help of the KM" he meant that with the U-boats tying up the very limited Allied escort ASW resources in 1942, the Japanese would have an easier time. (at least that's what he SHOULD have meant!) The Germans would not be able to get very far out of the Atlantic, there are enough targets already!

 

[Soren]

The KM subs wouldn't stray far from the Atlantic for any lon period of time as long as the USSR still existed, however with the USSR defeated the KM could comfortably engage in a prolonged war in the Pacific. In Freebird's scenario it is my understanding that the KM U-boats would only be there to sink the USN carrier fleet and any remaining ships after the Pearl Harbour attack, and then the IJN subs would take over employing German wolfpack tactics.

Now that having been said, it would've meanwhile been a whole lot easier for the German U-boats in Atlantic, with the US being unable to send many merchant ships and the British having to haul it nearly all alone. Isolating Britain wouldn't have been too hard in this case. What this means is that the Germans could send subs to the Pacific to help out the IJN, ofcourse utilizing the same refueling locations. And then ofcourse there was the milk cows, the Japanese would've undoubtedly have some huge milk cows with the task of refueling submarine force.

Hope that cleared up what I meant.

 

[Freebird]

The KM subs wouldn't stray far from the Atlantic for any logn period of time as long as the USSR still existed, however with the USSR defeated the KM could comfortably engage in a prolonged war in the Pacific.

Soren I don't think the KM boats with the shorter range would get into the Pacific, obviously it would be almost impossible to sneak through the Panama Canal. If they were to stray outside the Atlantic it would probably be only if the KM IJN have a base in the Indian Ocean (Madagascar).

In Freebird's scenario it is my understanding that the KM U-boats would only be there to sink the USN carrier fleet and any remaining ships after the Pearl Harbour attack, and then the IJN subs would take over employing German wolfpack tactics.

No actually I think the KM U-boats would be lucky if they could hit even 1 Carrier. The 3 Pacific US carriers were lost at "Pearl" the US would bring 3 or maybe even all 4 remaining carriers into the Pacific. The U-boats would be taking advantage of the 6 months+ of disorganization on the Atlantic Caribbean coasts to destroy as much shipping as possible.

Now that having been said, it would've meanwhile been a whole lot easier for the German U-boats in Atlantic, with the US being unable to send many merchant ships and the British having to haul it nearly all alone. Isolating Britain wouldn't have been too hard in this case.

Britain would not have been isolated, what is most likely is that Royal Navy would continue to run heavily escorted convoys to the UK, which the U-boats could not seriously impede. However this would be at the cost of the war effort in Egypt, Australia the Far East.

What this means is that the Germans could send subs to the Pacific to help out the IJN, ofcourse utilizing the same refueling locations. And then ofcourse there was the milk cows, the Japanese would've undoubtedly have some huge milk cows with the task of refueling submarine force.
Hope that cleared up what I meant.

I think the Germans WOULD re-build their supply-subs, but as I said earlier they wouldn't operate in the Pacific. As the North Atlantic became more protected they would look for targets in the South Atlantic, and make an occasional massed "wolf-pack" attack on a Halifax-Liverpool convoy, attempting to overwhelm the escorts. This would prevent the Royal Navy from pulling escorts from the N. Atlantic route and sending them to the Indian Ocean or Pacific. Again, this is basically what really happened, except that the Japanese never took advantage of it.

 

[Freebird]

Had the Germans and Japanese co operated and co ordinated their attack I have no doubt that they would have inflicted considerable losses to the allied vessels over and above the losses incurred.
However the allies would have responded differently and introduced convoys much sooner than they did off the USA coast. Losses of that size would have put ASW at the top of the Allied priority list.

The outcome of the war at least at one point largely hinged on the "Battle of the Atlantic" To me the "Battle of the Atlantic" now seems to fall into the same category as the BOB, not quite as close run as previously thought.

Here is the problem that the British face. They can aviod heavy losses by running well protected convoys, but with the limited ASW available most non-Atlantic shipping did not have much protection, if any.

Suppose for example that in the first 3 months of the war the IJN KM sink 2 million tons average per month. in months 4 5 they sink 1.5 million/month, and in month 6 this falls to 1.25 million.

After 6 months the Allies have lost 10.25 million tons, which might break down as 3.75 US 6.5 British (million tons lost). Of the British losses probably 1.75 million would be tankers, and 4.75 million would be "Dry cargo".

In the fall of 1941 the British have 15.5 million tons "Dry Cargo" capacity, + 5 million tons of tankers. The Shipping board statistics report that normally 10% of the total is unavailable at any one time, due to breakdowns, repairs, or in drydock fixing battle damage. (many were hit by torpedoes but didn't sink)

Of the 14 million available "Dry Cargo", the British fleets are shown on the map below. Every single fleet is strained and short of tonnage, there is no "Reserve" available. Most of the shipping runs in complicated routes, so it is very difficult to transfer quickly. For example, a (South Atlantic) ship leaves Britain with war supplies for West Africa and South Africa. In W. Africa it unloads some cargo, and loads additional raw materials for S. Africa. In S. Africa it unloads and then loads coal bound for Argentina. In Argentina it unloads the coal and then re-loads with bales of meat grain for the Caribbean. In Jamaica or Trinidad it unloads, then re-loads at Georgetown (Guiana) with cargo of Bauxite for Britain. The outbound ships of the Indian Ocean fleet are fully loaded with war supplies for Egypt, Malaya, India Australia, they then reload with meat from Australia, or raw materials from India, Malaya Africa. (Tin, Rubber, Bauxite etc.). The Australian fleet loads food for India Africa, and returns with goods raw materials for the domestic factories. The Pacific fleet supplies not only NZ, but also Fiji, Tonga, Tahiti New Caledonia. The Med fleet is used to supply Malta, Cyprus Tobruk, is also used by the Military for operations.


Here is the problem: Where can the British subtract the 4.75 million tons without severe consequences in operations? Unless they have some other option available (such as a Trans-Africa rail link) they would probably lose Egypt India