What if Germany followed Donitz's proposals to build a force of 300 U-boats?

[ArtosStark]

That's true, OTL Plan Z wanted everything done by at least the end of the 40's, though submarines would be easier and cheaper to build then aircraft carriers and battleships.

Subs are cheaper to build on a per hull basis. Per ton, submarines are the most expensive type of ship available in WW2. The ratio I have seen used most often is 100:35 in favour of BB's.

As a clarification, when you say Plan Z, are you meaning only those ships that were exclusive to the 1939 plan? That would be the 6 H-Class BB's, 3 O-Class BC's, 12 P-Class Panzershiff, 2 Graf Zeppelin CV's and 2 follow on CV's. If so, very little changes compared to OTL as none of those ships were completed and most were never laid down. At most you gain nine months of increased U-boat construction by not laying down those first ships and not ordering their components.

If you include the ships before 1939 then you have more time, but without any serious threat from Fast BB's the British can afford to reduce, slow down, or just not build some of the KGV's in favour of more Black Swan class sloops, Hunt class escort Destroyers, Flower Class Corvettes, or River Class sloops.

That fair, would changed numbers like 150ish subs be more realistic?

In peace time conditions the Germans had 10 Type VIIA's come into service between 1935 and 1937, an average of 5 per year. They had 24 Type VIIB's come into service between 1936 and 1940, and average of 6 per year. To make 150 subs between 1935 and 1939 they would need to build an average of 30 per year. To make 300, you would need 60 per year. That is an increase of a factor of 5 or 10, when the entire military is in a state of massive increase. This is probably going to hurt the Heer or the Luftwaffe somewhere and they were still much thinner than they wanted to be when War broke out IOTL.

Well yeah, but that didn't stop Japan, Germany, or Russia from building there own

No it did not, because they were unsuccessful in getting them banned. The reference was to show that Britain did very much consider submarines a threat.

That's true, but the tech was years away from being completed and German submarine tech would be more advanced as German submarine experience becomes more developed and refined

The tech was completed. The first underwater echo-ranging device was the Fessenden oscillator, patented in 1912 and equipping 10 Montreal built British H-Class submarines. This was separate to the extensive British use of Hydrophones in WW1. The first prototype ASDIC device was produced in 1917, with further refinements made in 1918 and first testing in 1920. They were in production by 1922. By WW2 the Admiralty had five different sets for carriage on different ship classes. Depth finding Sonar would have to wait until late war but it was an improvement not a necessity.

What was missing from the early British efforts were ahead-throwing weapons and better tactics. Use of ASDIC was interrupted by the ship moving over the submarine to drop its depth charge making it hard to accurately hit it. Improved tactics came with experience and at first involved one ship keeping its ASDIC on the target while another dropped the charge. Ahead throwing weapons were proposed earlier but the idea of using a spread of them was not, and so their effectiveness was limited.

If the main threat Britain appears to be German U-boats then that is likely where they will focus their training. It is a pretty short step to get to the solutions I have listed above. Greater focus on ASW is very likely to bring them out pre-war.

British political leadership would want to, however the stock market crash and overwhelming public opposition to any form of war with Germany would still hamstring British efforts to respond to German aggression, and they'd still likely fold until Czechoslovakia falls to Nazism as Hitler at least appeared like he'd honor treaties before then

The Great Depression lasted much less time in Britain than the US. It was effectively over by 1935 at latest. Opposition to war was predicated on the idea that war could be avoided by treaty and negotiation and that no one really wanted a war. ITTL Germany is working feverishly on a weapon that can only be designed for a repeat of a situation that affected the lives of everyone in Britain. IOTL the French were very worried about the Germans breaking the TOV. ITTL they are much less likely to be restrained by Britain and much more likely to get active British support. ITTL either the AGNT does not exist and Britain does not think Hitler is a basically decent fellow that they can work with, or he is immediately and massively breaking it.

I got my numbers from Johnathan Dimblebys battle of the Atlantic. Can't find the page it was in though, unfortunately. Great boon on the battle of the Atlantic imo and I'd highly recommend.

But the Commonwealth would have had to deploy there forces all over the world while Germany can just focus everything on a since front navally

I will have to take a look at some point as the numbers don't add up:
Hunt class Escort Destroyers
70 ordered 1939-1940, Average time to build is around 18 months. 12 months if they are in a hurry.
Black Swan Class Sloops
37 completed,1938-46(some were delayed or ordered later) around 15 months to build
Flower Class Corvettes
294 completed,225 ordered 1939-40, Can be built in merchant yards
River Class Frigates
141 launched 1941-1944
Loch Class Frigate
28 Completed 1944-1945
Castle Class Corvette
44 completed, 41 completed 1943-1944 (3 completed post war)

These were all designed for ASW in the Atlantic. This ignores the other destroyers and cruisers that would also be available due to the reduced surface threat.

Submarines during this time were thought of something like destroyers as technology off the time limited them to supporting fleet roles and commerce warfare was thought to be obsolete by convoys and sensor technology. Tactically too, the German idea of the wolf pack rather then solo gunning it also allowed greater ability to raid commerce and attack ships then the British were prepared for as they were used to either solo subs or using them in Port attacks

Most of that is true of WW1, not WW2. Those were possible uses for submarines but the British did not focus on them to the point of ignoring their threat to shipping. The wolf pack idea had actually first been tried in WW1 and was a disaster for the Germans. WW2 communication technology made it possible but this can be seen as the Germans entry fee to be able to sink escorted shipping at all.

 

[sparky42]

As mentioned in the other threads and here already, ramp up sub building then the RN will respond, the British general rearmament will respond so the general British military will be in a better position, and the Treaty Ports in Ireland will be retained giving the RN a much better position for the convoys.

 

[TDM]

I partially agree with your point here, if Germany needs the resources to build that many submarines, they're gonna have to cut a few corners somewhere. Maybe Goering pisses off Hitler and the luftwaffe loses one of her key supporters or Hitler orders less trucks for the army?

Both would be big problems for taking France in 1940, and if that doesn't go according to OTL all this is moot.

Though the German naval plan imo was screwed up and they didn't really need so many battleships/panzerschiffs, and instead should have focused on a smaller force for coastal defense as the regular German navy had zero hope of defeating the Royal Navy.

Right but like I said it's not just a few less Battleships. If the KM gives up it offensive surface fleet outside of coastal defence. How are they going to do Norway / how well does Norway go against the RN. It will also allow the RN and Fleet air arm to concentrate on ASB

By the time Germany actually had the ability/political will really needed build up her fleet the 1935 naval treaty was in effect and allowed Germany to build a sizable submarine fleet with the possibility to increase the number of subs by cutting down on other things. Besides, Germany could just get ignore treaty limitations like IOTL to get just a few more subs in before the war.

1935 is not going to be early enough (especially as they weren't planning to be at war with Britain and France in 1939 anyway), plus the naval treaty required balanced fleet with proportional number thresholds (i.e. you couldn't just go all in U-boats)

They can of course ignore treaties but doing so is a red flag to Britain

The British navy didn't really think all that much of submarines, instead focusing on capping the development of other capital ship Navy's compared to her own and focusing R&D on radar tech. Besides, the regular British convoy defense fleet was laughably tiny compared to WWI from 449 ships in WWI to just 135 in WWII at the height of the U-Boat era. If Germany had 100 ships they really could have put Britain in a rough spot and extended the war by a year or so.

The British are well aware of the risk of U-boats as this is exactly the same tactics used in WW1 and Britain hasn't stopped being an Island reliant on imports. Also as pointed out I'm not sure you have the right figures (certainly in terms of available ships overall). Plus again you are looking at an ATL of hundreds more U-boats. If Britain think's there are a lot more U-boats about then they will put out more ASB/Convey craft. Also the RN in WW1 and WW2 is different you can just compare abstract numbers like that

True, the British won't pussyfoot around, but like iotl I expect them to be caught off guard as the British worried more about capitals then subs.

But if there are no capitals than they don't need to worry about them right?

You'd need to changed the entire British Navy's opinion on submarines to have them take the threat more seriously then just chucking radars at it because even if the British had radars they wouldn't have enough convoy ships to take advantage of it effectively. Coupled with this program also probably fixing the German torpedo issue things could get messy real quick for Britain

Again I disagree with your basic assumption on the RN's attitude to U-boats

As was stated in the last thread, 300 U-boats only makes sense if German strategists preternaturally know that Britain will be the main enemy as early as 1935. This just wasn't the case.

Good point, Hitler's hoping to avoid war with Britain in the mid 30's it's unlikely he going to sign off on a big increase in KM spending that's only really aimed at Britain and not much help for beating France

 

[Vabasion]

Things never happen in a vacuum, the German decision to build submarines is impossible to hide. You can’t just hide 300 ships and their crews and the training of crews. You can’t hide the fact that you’re building submarines nor who they are directed against. You can’t play it off as anti Soviet measure or security from the Czechs. Britain would know. And for each submarine built they can build 8 or so Flower corvettes as escorts. Heavy assets of the royal navy would be free to act and participate in operations since there is no need to bottle up any large German assets. And escorts are easier to make than submarines

 

[steamboy]

Things never happen in a vacuum,

When it comes to "If the Nazi's had X and Y" it often does. You'd be surprised at how many threads about Nazi's having X Y or Z rely on goalpost moving, the nazi's doing everything in a vaccum or handwavium that amounts to 'Because'.

 

[The Tai-Pan]

The United Kingdom would love for any coming war to be fought on naval terrain. That's right in their wheelhouse.

 

[sparky42]

When it comes to "If the Nazi's had X and Y" it often does. You'd be surprised at how many threads about Nazi's having X Y or Z rely on goalpost moving, the nazi's doing everything in a vaccum or handwavium that amounts to 'Because'.

You forgot the Allies, particularly the Admiralty taking daily doses of lead paint instead of tea.

 

[EWHM]

A more significant and achievable POD would be having fully operational torpedoes at the start of the war. Amusingly, most countries had bigtime torpedo issues at the beginning of WW2, including the US and Germany.

 

[cardcarrier]

A program could start fairly early

Germany disclosed as early as 1934 that they where starting to build Uboats and would no longer follow the Treaty of Versailles

A program like that is supremely impractical for prewar Germany, if only due to lack of suitable bases to sortie the subs to their patrol zones; forgetting that in early 1938 they entered a permanent raw materials crisis, so the production quality of the boats actually started going down

Trying to starve the Britain out with subs; when all of their ports are within moderate range of much cheaper, dual purpose, and more effective land based bombers is as dumb as it sounds

The reichmarks invested into the Uboats where arguably more wasteful, given the era in which they where spent than even the V weapons programs. The uboat arm in the second war on a tonnage/money invested basis was not even half as effective as they where in the first war. Much less paranoid people than Hitler would have had Doenitz shot, rather than name them as their successor

 

[Crowbar Six]

Both would be big problems for taking France in 1940, and if that doesn't go according to OTL all this is moot.




Right but like I said it's not just a few less Battleships. If the KM gives up it offensive surface fleet outside of coastal defence. How are they going to do Norway / how well does Norway go against the RN. It will also allow the RN and Fleet air arm to concentrate on ASB



1935 is not going to be early enough (especially as they weren't planning to be at war with Britain and France in 1939 anyway), plus the naval treaty required balanced fleet with proportional number thresholds (i.e. you couldn't just go all in U-boats)

They can of course ignore treaties but doing so is a red flag to Britain





The British are well aware of the risk of U-boats as this is exactly the same tactics used in WW1 and Britain hasn't stopped being an Island reliant on imports. Also as pointed out I'm not sure you have the right figures (certainly in terms of available ships overall). Plus again you are looking at an ATL of hundreds more U-boats. If Britain think's there are a lot more U-boats about then they will put out more ASB/Convey craft. Also the RN in WW1 and WW2 is different you can just compare abstract numbers like that



But if there are no capitals than they don't need to worry about them right?



Again I disagree with your basic assumption on the RN's attitude to U-boats



Good point, Hitler's hoping to avoid war with Britain in the mid 30's it's unlikely he going to sign off on a big increase in KM spending that's only really aimed at Britain and not much help for beating France

You are also likely to see the Canadians being encouraged to start domestic production of corvette's pre 1939, if the Germans are building a lot of U Boats.

 

[Theoretical_TJ]

There’s two ways in this era to make sure Britain has NO interest in appeasement and wants to crush Germany.

Open preparation for and building vessels for the Sea Mammal and building an armada of subs, both of which are existential threats to Britain in particular.

An interesting ASB timeline might be where Germany gets a gradual increase of extra subs as they build but that the ASB brainwashes both the British and Germans to not notice them beyond increasing ASW training and efforts for the Brits and additional crews and logistics for the Germans.

 

[cardcarrier]

There’s two ways in this era to make sure Britain has NO interest in appeasement and wants to crush Germany.

Open preparation for and building vessels for the Sea Mammal and building an armada of subs, both of which are existential threats to Britain in particular.

An interesting ASB timeline might be where Germany gets a gradual increase of extra subs as they build but that the ASB brainwashes both the British and Germans to not notice them beyond increasing ASW training and efforts for the Brits and additional crews and logistics for the Germans.

Germany's fleet was expressly built for commerce raiding, and Britain gave them treaty authority to build more subs than they had the capacity to even try to build anyway. The ww2 German fleet strategic mindset and it's ships where a joke and gigantic net negative to the axis war effort

Britain could afford to be 10000% percent more complacent about the German fleet than they where historically; now the German airforce and the Japanese armed forces on the other hand... people dropped the ball on that one, badly

 

[Garrison]

When it comes to "If the Nazi's had X and Y" it often does. You'd be surprised at how many threads about Nazi's having X Y or Z rely on goalpost moving, the nazi's doing everything in a vaccum or handwavium that amounts to 'Because'.

Basically a good TL starts with 'change A and reason out how that affects B,C,D etc'. A bad TL starts 'I want Z to happen, how do I alter A,B,C, etc. to make that happen?' And invariably the British doing nothing in response to some piece of Nazi clairvoyance is practically mandatory to get to 'Z'.

 

[Julian]

One problem with focusing solely on submarines that I don't often see discussed is that it means willfully abandoning the North Sea to the UK and the Baltic to the USSR in the interwar period. German naval strategists in the late 1920s and 1930s had 3 basic tasks in a war with the USSR, UK/France, or some combination of the three:

1. Protect Germany's coasts.

2. Secure or contest Germany's immediate area of operations (North and Baltic Seas).

3. Cut off supplies to the UK.

The first two require some sort of modern fleet of heavier warships. Without any kind of modernized surface fleet, even merely in existence as a "fleet in being", Germany has very limited means by which to prevent British/Soviet vessels from ranging freely throughout the region without worrying about any German BBs or heavy cruisers popping up. Aircraft alone aren't suitable for picking up the slack. This allows the UK to maintain a much closer blockade than the Channel + the GIUK gap while preventing Germany from having any means by which to secure its iron ore supplies from Norway. The USSR can range in the Baltic aggressively.

A 300 U-Boat strategy is very helpful if you have bases extending from Nantes to Norway and the UK is your only opponent. Less so if you're confined to the SE angle of the North Sea and the Royal Navy can pen you in without even the slightest ability to respond. In 1933-1939 the Kriegsmarine was planning for the latter conflict, not the former.

 

[Jellico]

Germany's fleet was expressly built for commerce raiding, and Britain gave them treaty authority to build more subs than they had the capacity to even try to build anyway. The ww2 German fleet strategic mindset and it's ships where a joke and gigantic net negative to the axis war effort

The commerce raiders had a hard counter in the three battle cruisers even before cruiser pile-ons were considered.

The trick is not to deny German a navy. It is to divide their interest into manageable blocks.

 

[McPherson]

One problem with focusing solely on submarines that I don't often see discussed is that it means willfully abandoning the North Sea to the UK and the Baltic to the USSR in the interwar period. German naval strategists in the late 1920s and 1930s had 3 basic tasks in a war with the USSR, UK/France, or some combination of the three:

1. Protect Germany's coasts.

2. Secure or contest Germany's immediate area of operations (North and Baltic Seas).

3. Cut off supplies to the UK.

The first two require some sort of modern fleet of heavier warships. Without any kind of modernized surface fleet, even merely in existence as a "fleet in being", Germany has very limited means by which to prevent British/Soviet vessels from ranging freely throughout the region without worrying about any German BBs or heavy cruisers popping up. Aircraft alone aren't suitable for picking up the slack. This allows the UK to maintain a much closer blockade than the Channel + the GIUK gap while preventing Germany from having any means by which to secure its iron ore supplies from Norway. The USSR can range in the Baltic aggressively.

A 300 U-Boat strategy is very helpful if you have bases extending from Nantes to Norway and the UK is your only opponent. Less so if you're confined to the SE angle of the North Sea and the Royal Navy can pen you in without even the slightest ability to respond. In 1933-1939 the Kriegsmarine was planning for the latter conflict, not the former.

It is that blindness to airpower that cost the UK the Norway campaign and protected the Swedish iron ore traffic from the Red fleet. Also if one looks at chokepoints to the Baltic

These 8 narrow chokepoints are critical to the world's oil trade

Over half of the world's oil supply moves through these eight chokepoints.

www.businessinsider.com

one will see that neither the British or the Russians have "free access" if the Germans have as much as a fast attack craft presence in the Skagerrak or the Bay of Riga.

"Shoreline determines the use of the sea." --Mahan

 

[Finbarr the Fair]

It is that blindness to airpower that cost the UK the Norway campaign and protected the Swedish iron ore traffic from the Red fleet. Also if one looks at chokepoints to the Baltic

These 8 narrow chokepoints are critical to the world's oil trade

Over half of the world's oil supply moves through these eight chokepoints.

www.businessinsider.com

one will see that neither the British or the Russians have "free access" if the Germans have as much as a fast attack craft presence in the Skagerrak or the Bay of Riga.

"Shoreline determines the use of the sea." --Mahan

I blame the early establishment of the RAF as an independent service for this. Plus its Bomber Baron fantasies.

 

[Vabasion]

A program could start fairly early

Germany disclosed as early as 1934 that they where starting to build Uboats and would no longer follow the Treaty of Versailles

A program like that is supremely impractical for prewar Germany, if only due to lack of suitable bases to sortie the subs to their patrol zones; forgetting that in early 1938 they entered a permanent raw materials crisis, so the production quality of the boats actually started going down

Trying to starve the Britain out with subs; when all of their ports are within moderate range of much cheaper, dual purpose, and more effective land based bombers is as dumb as it sounds

The reichmarks invested into the Uboats where arguably more wasteful, given the era in which they where spent than even the V weapons programs. The uboat arm in the second war on a tonnage/money invested basis was not even half as effective as they where in the first war. Much less paranoid people than Hitler would have had Doenitz shot, rather than name them as their successor

I keep seeing the Donitz was incompetent argument recently could I know for the reason and where to read more about it.

 

[cardcarrier]

I keep seeing the Donitz was incompetent argument recently could I know for the reason and where to read more about it.

his entire command of the submarine arm and later the navy; the entire war

his command took in excess of 80 percent casualties, and over 200 boats where lost on their first patrol, because he cared more about teaching them nazi political theory during their basic training than how to drive the submarines

if youd like to see a case study in what command looked like under Doenitz... operation tanne ost, regimental level sea lion

 

[McPherson]

You would have read me discuss this opinion. Doenitz was clueless as to what he had as a tool.

Discussion.

My two farthings.

The best submarine admirals to lead such services were Ralph Christie on the technology side and Charles Lockwood for the operational art in WWII. Hiram Rickover during the Cold War was undoubtedly the greatest admiral of his era.

The naval staffs who supported such men innovated
a. chokepoint blockade
b. the submarine as sea denial, control access and blockade weapon.
c. the submarine as the premier ship-killer, either as blockader or as a weapon platform in a major fleet action.
d. underwater dogfighting (submarine versus submarine).
e. the KILLBOX.
f. naval espionage.
g. the flow strategy.
h. the submarine as the decisive strategic platform. (Sorry bomber barons, but runways can be knocked out. Submarines are hard to find and kill.)
i. mission guidance package (sealed patrol orders.)

I would suggest i. , was possibly the WWII most important. "Keep off the !@# !@#$ed radio." which is the true origin of "THE SILENT SERVICE", was the likeliest best lesson learned from the inept Karl Doenitz which the USN digested from British operations against that amateur. Most British kills against the U-boats was generated by radio direction finding the yakking U-boats as they reported back home on weather, fuel states, or even idiotic items as required inventory or supplies expended bureaucratic "Here I am, please come and kill me now, Royal Navy hunters." nonsense. One does not have to break German naval codes to RDF a yakking radio source in the middle of the Atlantic. One just has to put a bomber over the loudmouth and sink him.

Then we have the failure of BdU and the German naval staff to do basic obvious stuff...

a. --like map the Gulf Stream and Great Pacific Current to learn how to FIGHT using the thermo-cline and what underwater weather does to sound refraction.
b. --the Americans and British did not have multi-channel sonar in WWII (single channel only). The Germans did (GsF), but never understood how to use acoustic interferometry properly to detect and plot a track intercept to loud allied convoys. One does not need wolfpack tactics if one can listen out to 1000 km and make the convergence zone corrections to get a bearing solution on such a loud slow moving target array set. Americans, for example, could at least hear out to the first convergence zone underwater with their single channel sound gear and had practiced sprint and drift experimentally before WWII. The British may have experimented with it as well, but I do not find it open sourced.
c. --Doenitz liked to use gimmicks instead of techniques when he was bollixed. True he pushed for pattern running torpedoes and acoustic torpedoes which is correct "solve it in the weapon, not the launcher" military engineering, but the solutions he pushed were easily countered by noise makers and open space anti-torpedo counter-maneuver convoy formation arrays. The Americans when faced with the same problem, against the wily Japanese, decided that wake-homing was the solution. They could not solve it, but they knew from op-art analysis what had to be solved. Flak-boats was a gimmick to counter Leigh Light, ASV, and LRMP attacks. The radar warning receiver was a stab at the right answer but Doenitz rejected the advice of FRENCH radar specialists who suggested that the British might be using centimetric wavelength radar. How about the snort? Used as a survival tool by the KM, it was not used the DUTCH way, to dive awash, get into the shallows, and ambush from close inshore (alligator tactics.). I write a lot about that one in "Those Marvelous Tin Fish". Funny thing is that one other set of submarine operators used alligator tactics without the snort, especially in the island cluttered Southwest Pacific Ocean Area. This worked well against sonar-equipped Japanese subchasers, who died at American hands by the score.

==============================================

But the kicker and the one which shows that Doenitz was not qualified to command a dinghy, was his persistent use of the tonnage gimmick instead of proper economic warfare analysis and the flow strategy against the British.

What does that mean? Doenitz thought if he could sink enough freighters he could starve the British out. That is tonnage. What frightened the British, really frightened them, was that Doenitz would go after OIL TANKERS-especially Venezuelan or American oil tankers which were their major source of AVIATION light sweet crude gasoline. Picking a key resource category target and killing it, is called FLOW STRATEGY or bottleneck blockade.

Hence; I regard Doenitz as an amateur. I call him Luddite because he would not listen to his technology experts, op-art specialists or even his own staff. He was narrow-minded, nonadoptive of new ideas, inflexible, and incredibly stupid about naval warfare in general and submarines specifically. His insistence on the Type VII crew killer in preference to the Type IX, despite data which showed more freighters killed per U-boat lost with the Type IX is indicative of such stupidity. Reserve Buoyancy actually matters for submarines as much as large escape hatches do for tanks for crew safety, survival, and fighting efficacy in a U-boat.