U-boat base in the S. Atlantik

Here's an idea I've been kicking around for a while now.

When Britain & France declared war on Germany towards the end of 1939, the Kriegsmarine should have known from their WW1 experience that while they'd get the best bang for their U-boat buck in the N. Atlantik, that's also where the Allies would institute convoys & concentrate their ASW assets. They also should have known that while surface warships are nice for showing the flag, U-boats make much better commerce raiders. OK-- so Hitler liked big surface warships, & he promised there wouldn't be a war 'til they had time to build up the fleet, & all that nonsense. So the KM is stuck with its 3 'Deutschlands', its 2 'Gneisenaus', the 2 'Bismarcks' being built, & its 'Hipper'-class heavy cruisers.

...but Germany also had 4 ex-Lufthansa catapult ships-- the 'Schwabenland', 'Westfalen', 'Ostmark' , & 'Friesland'. These ships had been used in the late '30s to operate a mail service carried by flying boats to N. & S. America. At the outbreak of war, under Goering's idiotic doctrine that 'everything that flies is mine', they were taken over by the freakin' Luftwaffe & used for basically nothing.

Well, I've never liked Goering much anyway. Let's have one of his hunting buddies shoot & kill him during a stag hunt in the summer of '39, before the outbreak of war. (I know there aren't any deer seasons in the summer, but then Goering never had to abide by the rules.) Bereft of his political influence, the LW can't take over the ships, which end up in the KM where they belong.

Now we have the basis, not for a core strategy, but for a nice little secondary strategy, peripheral to the main war effort. Not a war-winner, but still interesting.

The KM takes those 4 catapult ships & equips them with the same sort of self-disguising capability that it gave to commerce raiders like the 'Atlantis', the 'Orion', & so forth. Folding aircraft cranes, telescoping funnels, extra funnels, & plenty of different-colored paint. In place of their previous 2/Ha-139 float planes (38,600 lb. takeoff weight, 200mph, 3300-mile range) we give each ship about 5 to 8/Ar-196 float planes (7300 lb. takeoff weight, 200mph, 500-mile range) with extra fuel tanks (~750 mile range?). 3 operational & the rest in crates. Or maybe 3 BV-138 flying boats (32,000 lb. takeoff weight, 175mph, 2800-mile range). 2 operational & 1 in a crate. No guns, though. Instead, the catapult ships are refitted as U-boat tenders with repair shops, refueling capability, & torpedo reload facilities, & they're false-flagged as neutral Scandinavian merchant ships. Scientific research ships, even. (The 'Python' carried fuel & spare torpedos for U-boats, so equip the catapult ships with that capability too.)

Let's say the refit takes 3 to 6 months. Now, beginning around Jan. 1940, by rotating our catapult ships into the S. Atlantik, we'll have the basis for a remote U-boat base with float plane reconnaissance. If we want, then we can now operate even short-legged Type-VII U-boats in the S. Atlantik. But let's say we more urgently need 'em in the N. Atlantik, which is where most of the merchant shipping is & where their faster dive time makes 'em more survivable. So we end up with 4 to 6 Type-IX U-boats on extended patrol in the S. Atlantik, where they no longer have to waste half their time getting back & forth to their patrol areas & their effectiveness is now enhanced by float plane recon. The catapult ship just anchors at some remote islet like Trindade & Martin Vaz, St. Peter & St. Paul, Rocas Atoll, or Fernando de Noronha; or in good weather it just drifts on the open ocean. (The 'Atlantis' did this several times.) Your float planes & your U-boats should provide the catapult ship with enough advance warning of an Allied warship to get out of its way.

In fact, let's operate the catapult ships in pairs. That way, by the time the Allies suspect what we're doing, we can allow a suspected catapult ship to be seen in some area far away from where we're really operating & draw the enemy off in the wrong direction. Or we can hold one in reserve in the Antarctic in case we lose the other one. And if we do lose one, then in either case we can resume operations almost immediately with no loss of tempo.

Commerce raiders can also have their effectiveness enhanced by float plane recon, so let's say that we pair a couple of commerce raiders with each catapult ship. Commerce raiders were designed as long-range platforms-- the 'Atlantis' logged 622 continuous days at sea-- so they're unlikely to need to refuel, but they do provide a limited self-defense capability vs AMCs & they also benefit from the float plane recon. The catapult ship can also serve as a nucleus & command ship for a prize fleet. In OTL the 'Atlantis', the 'Orion', the 'Pinguin', & other commerce raiders did maintain prize fleets at sea for limited periods of time. Our 2 commerce raiders can rotate between the Indian Ocean & the S. Atlantik.

In OTL the 'Deutschland'-class raider 'Admiral Scheer' made a cruise to the Indian Ocean, & of course the 'Graf Spee' was active in the S. Atlantik until it got sunk. Had the 'Graf Spee' had a nearby cruiser, or even a U-boat or two, then it might well have survived, so putting a catapult ship down there to maintain U-boats on-station is good news for the pocket battleships too. So also keep a 'Deutschland'-class raider in the area. (And before you beat me up about underway refueling, both the 'Atlantis' & the 'Admiral Scheer' refueled at sea from the captured tanker 'Ketty Brovig'.)

The 'Gneisenaus' were kept out of the S. Atlantik by limited fuel tankage, but with a refueling capability down there we've now removed that problem. We can now rotate the 'Gneisenaus' with the 'Deutschlands' to protect the catapult ship.

The KM also had auxiliary ships to support the 'Deutschlands' & the Type-IX U-boats-- ships like the 'Altmark' & the 'Python'. Since we're using so much fuel to maintain not just our U-boats, but also our 'Deutschlands' & especially our short-legged 'Gneisenaus', maybe we want to pair up an 'Altmark' or a 'Python' with the catapult ship(s) too. They were essentially combination fuel tankers & stores ships anyway.

...so this leaves us with an active & a reserve catapult ship, 6 to 16 aircraft, an auxiliary stores ship, 4 to 6 (or more) Type-IX U-boats, a couple of commerce raiders, potentially a prize fleet, & either a 'Deutschland'-class raider or a 'Gneisenau'-class battleship-- or occasionally both.

Yeah-- you're right. The RN could have hunted 'em down & killed 'em all. In fact, it'd have to. A KM force like we're describing here could have practically shut off all commercial ship traffic thru the S. Atlantik & Indian Oceans, & possibly from the Caribbean too. (Thru the end of 1940 the UK imported most of its petroleum products from the Persian Gulf thru the S. Atlantik, although by early 1941 they got most of it from the Caribbean region.) But allocating resources to hunt down & kill these ships in the S. Atlantik would have diverted resources away from the N. Atlantik campaign, where the UK was fighting for its very survival.

Making the best use of very limited KM resources to spread the RN thinner & thinner was the KM's best chance-- if you don't think they can possibly win, then of prolonging the war.
Thegn.
 

Cook

Banned
When Britain & France declared war on Germany towards the end of 1939, the Kriegsmarine should have known from their WW1 experience that...
It's important to remember that the Germans were not planning a general war against the western democracies for another four years, by which time the Kriegsmarine would have been substantually stronger.
 
It's important to remember that the Germans were not planning a general war against the western democracies for another four years, by which time the Kriegsmarine would have been substantually stronger.
Yeah, I get that, which is why my POD is '39. Prior to that there was no serious advance planning for an immediate war, which is why when Bernhard Rogge reported to KM hdqtrs. to find out about the 'Atlantis' he found that he'd have to basically figure out everything for himself as he went. They'd basically found him a ship-- everything else was his problem.
Thegn.
 

BlondieBC

Banned
Well it helps. What you propose is basically a big part of what I used for my TL, where I called it a Diamond and a Freighter in WW1. It is a sound concept, and will help win the war, but you have a series of problems that has to be dealt with, and will limit effectiveness.

1) The U-boats have to keep enough fuel to always be able to make it to the nearest naval base. The AMC you propose will eventually die. I went with progressively longer range U-boats until I ended up with U-boats with 25,000 nm range. I think you have to use the longest range U-boats, you just keep them topped off with fuel.

1B) I had bases in both West and East Africa, so the run is not as far. If you were doing this plan, I would think real hard about having merchant ships in ports in French West Africa as backup in case something has happened to the AMC.

2) Using the radio will give away your position. Eventually, the RN gets triangulation units in the South Atlantic. The AMC is much slower than RN navy ships, so once found, it normally dies unless you can have the U-boat sink the RN warship or maybe the plane off the ship. So you either are forced into limited life or having the the AMC not use the radio but in an emergency but have a set schedule on stops, which the U-boats also have..

3) You would put some guns on for self defense. Probably 1-2 15cm guns for surface ships, some AA guns, and a few light machine guns.

4) You might well also want to keep extra sailors and extra guns in the hold. Any surface ship caught without it using the radio can be convert into an AMC. One 15cm gun and a crew make an AMC. You have a lot more issues since you don't have bases nearby. I think you really want to cheat and use some French ports or anchorages if you go this strategy. For me, it was much easier because I sailed them to Douala and refit and a dry dock if needed. And I had unlimited crews, plenty of guns, and ample ammo.

5) You float planes do provide warning, but they also give away that you have a ship in the area. If you are sending out airplanes, you might was well treat as a CVL escorted by U-boat and create a zone of exclusion a few hundred miles across. This will be highly effective, but will also mean the RN sends down a real CVL to sink you. Short but glorious life. Since you are on a shoe string budget far from resupply, you have many risky tradeoffs.

6) I do like the idea of trying to have U-boats escort the surface warships such as Graf Spee. You have issues with speed, but the combination of surface ship + possible U-boat creates a tougher tactical problem for the UK to solve.

7) I do think you can shut the South Atlantic, I don't think the Caribbean. First it will anger the USA. Second, you don't want your AMC within easy airpower of the RN bases in the Caribbean. You get a big enough gain by having the Italians shut the Med, and you plan shutting the South Atlantic for a few months. You are basically running a very light budgeted war on how to beat the UK. Shut Med Sea, then shut South Atlantic. Then deal with North Atlantic issues.

Now if you were writing a TL, there is huge variability of outcomes. These ships might die pretty quick, or will luck/skill by the Germans might go on for a year or better.


Now there are huge benefits of more time on station, forcing the UK to spread its naval forces, forcing them to reroute traffic, and forcing them to consider convoying, attacking less defended ships, and deterring some neutral ships from trading. And in the big scheme of things, a few hundred sailor and a few ships is a small cost in a WW2 budget.
 
What you propose is basically a big part of what I used for my TL...
I thought about trying this in WW1, but aircraft were too limited, reducing the benefit to be gained; & there were no dedicated catapult ships to use back then.

1) The U-boats have to keep enough fuel to always be able to make it to the nearest naval base.
No problem there. I totally agree.

The AMC you propose will eventually die.
By "AMC" are you using a British term to refer to a German ship? The commerce raider? Because if you are, then almost all of the commerce raiders eventually got sunk. That doesn't invalidate the concept. Military forces are there to be used. Expended, if you will.

I went with progressively longer range U-boats until I ended up with U-boats with 25,000 nm range.
The Type-151 U-cruiser (7 boats in class) had a 25,000 mile range. So did the WW2 Type-IX/D, although it came out too late for my POD. Anyway, I think that torpedo availability was as big a deal as fuel. U-boats & US subs often had to go home just for more torpedos.

1B) I had bases in both West and East Africa, so the run is not as far.
That's a diplomatic issue, & if any country in those regions declares for the Axis then it'll be blockaded & suffer economic & diplomatic sanctions. What's in it for them?

1B) I would think real hard about having merchant ships in ports in French West Africa as backup in case something has happened to the AMC.
OK-- I thought about it. Same problem as above. Only here you're talking about "the AMC" as if you mean the catapult ship. In my proposal I have a catapult ship to handle the float planes & act as primary sub tender, an auxiliary stores ship to carry extra fuel, spare parts, groceries, & stuff; a couple of commerce raiders to benefit from the float planes & provide a limited self defense capability, & a 'Deutschland' or a 'Gneisenau' for more heavy firepower. Plus the U-boats, of course.

2) Using the radio will give away your position.
The KM was real bad at signals discipline. That's hard for me to deal with, because I'm ex-military & signals discipline was drummed into me for 18+ years. I even helped drum it into other people. Fixing this introduces a new element that violates the minimum-change rule. Still, I think you have to.

The slow elements-- catapult ship, auxiliary, & commerce raiders-- are all on radio silence. Only the aircraft, the warships, & maybe rarely the U-boats are allowed to transmit from positions at least 300nm away from wherever the slow elements are. You've got a rendezvous schedule so if the slow elements aren't where you left 'em then you know where to find 'em. The rendezvous schedule doesn't rely on the slow elements being at any particular place, but on them being within range to launch a float plane to drop a written message.

3) You would put some guns on for self defense.
Flak, yeah, but nothing heavier. No point. The catapult ship & the auxiliary can't defend themselves anyway. And if you do, then next you'll need magazines & ammo hoists that'll take more time to install & take up space that's better used for torpedos, fuel, spare parts, repair shops, groceries, & everything else you need. Part of a sub tender's job was also to provide medical & recreational facilities & showers for guys who were on long, grueling patrols. Also, the 15cm you suggest would require extensive bracing & reinforcing of the decks. The 'Atlantis' actually had hers below decks, behind 18th Century-style gunports, because the decks wouldn't support 'em.

5) Your float planes do provide warning, but they also give away that you have a ship in the area.
Hopefully the enemy will assume that any float plane they sight is from the 'Deutschland' or the 'Gneisenau', which they know is in the area.

You have issues with speed, but the combination of surface ship + possible U-boat creates a tougher tactical problem for the UK to solve.
No serious issue with speed as long as the primary mission of the U-boat is escorting the warship. If it's commerce raiding then it could be anywhere, but if it's on an escort mission then it'll be submerged somewhere in the vicinity, & the warship can draw the enemy right across its torpedo solution. The 'Graf Spee' wasn't fast enough to outrun the 'Exeter', but she was fast enough that the 'Exeter' would have taken 4 hours to close from 20 miles away. Longer than that IRL because of time lost compensating for target course changes, zig-zagging to complicate the target solution, & so forth. It could have taken 8 to 12 hours.

7) I do think you can shut the South Atlantic...
Briefly & temporarily, but with 4 catapult ships you can keep this up for at least 3 to 6 months.

I don't think the Caribbean.
You're right again. The Caribbean thing is a stretch, & it only becomes a hi-payoff target in '41 anyway because of the oil shipments. Prior to that it's mainly the Indian Ocean trade, the effect on neutrals, & the inefficiency of getting the UK to set up a convoy system in the S. Atlantik that you're after.
Thegn.
 

BlondieBC

Banned
By "AMC" are you using a British term to refer to a German ship? The commerce raider? Because if you are, then almost all of the commerce raiders eventually got sunk. That doesn't invalidate the concept. Military forces are there to be used. Expended, if you will.

The Type-151 U-cruiser (7 boats in class) had a 25,000 mile range. So did the WW2 Type-IX/D, although it came out too late for my POD. Anyway, I think that torpedo availability was as big a deal as fuel. U-boats & US subs often had to go home just for more torpedos.


That's a diplomatic issue, & if any country in those regions declares for the Axis then it'll be blockaded & suffer economic & diplomatic sanctions. What's in it for them?

The slow elements-- catapult ship, auxiliary, & commerce raiders-- are all on radio silence. Only the aircraft, the warships, & maybe rarely the U-boats are allowed to transmit from positions at least 300nm away from wherever the slow elements are. You've got a rendezvous schedule so if the slow elements aren't where you left 'em then you know where to find 'em. The rendezvous schedule doesn't rely on the slow elements being at any particular place, but on them being within range to launch a float plane to drop a written message.

No serious issue with speed as long as the primary mission of the U-boat is escorting the warship. If it's commerce raiding then it could be anywhere, but if it's on an escort mission then it'll be submerged somewhere in the vicinity, & the warship can draw the enemy right across its torpedo solution. The 'Graf Spee' wasn't fast enough to outrun the 'Exeter', but she was fast enough that the 'Exeter' would have taken 4 hours to close from 20 miles away. Longer than that IRL because of time lost compensating for target course changes, zig-zagging to complicate the target solution, & so forth. It could have taken 8 to 12 hours.


Briefly & temporarily, but with 4 catapult ships you can keep this up for at least 3 to 6 months.


You're right again. The Caribbean thing is a stretch, & it only becomes a hi-payoff target in '41 anyway because of the oil shipments. Prior to that it's mainly the Indian Ocean trade, the effect on neutrals, & the inefficiency of getting the UK to set up a convoy system in the S. Atlantik that you're after.
Thegn.

AMC - Armed Merchant Cruiser. I use it for any surface ship not built as a warship converted to a warship. I 100% agree about losing forces is required in a war. The Germans always worried too much about losing a few sailors in second rate ships. The Germans benefit with a more callous attitude toward the lives of sailor. In a war where 10K lost in a battle was common, the Germans were very sensitive about 1K dead sailors. Too much emotion, too little cold logic.

None of my U-boat are exactly the WW1 version, but yes I did end up with a modified U-151 type U-boat being used in the distant oceans. And on the supplies, also don't forget food, spare crews, medical, and R&R. I always figured that they kept about 50% of a spare crew on each AMC, so the men did not literally spend years in a U-boat.

Yes, the diplomatic issues are harder in WW2. I think French West Africa is doable with plausible denialibility. You don't keep the ship in some main french port, but have it in some anchorage somewhere.

Your radio ideas make sense.

On the using the surface ship as bait for the U-boat, I came to the same conclusion. Chasing either an AMC or warship with multiple U-boats setting up for a shot normally ends up with a U-boat killing the surface ship. You can't zig/zag and chase at full speed.
 
I'm seeing this as an RN nightmare.:eek::eek::eek: To begin with, just adding a fuel/torpedo resupply capability opens the entire East Coast of North America almost from Day One, plus the SAtlantic, in ways the Germans couldn't dream of OTL.:eek::eek: The strain on ASW patrol aircraft, let alone convoy escort, is going to be enormous.:eek::eek: (The total effect is more like:eek::eek::eek::eek::eek::eek::eek::eek::eek:)

See, this reduces turnaround time, which is a big impact on effectiveness: faster turnaround means less time in transit means more time (& more boats) on patrol station means more shipping sunk...means more Allied:eek::eek::eek: As for "longer-ranged U-boats", you've just wiped out the need for them: the supply ships act as forward bases.

Doing this drastically increases demand for corvettes & VLRs in Iceland & Newfoundland...& the Bahamas, & Bermuda, & the Azores, & the Canaries, & Brazil, &...:eek::eek::eek:

Add to that the increased flexibility you give to raiders like Spee & the Twins, & to AMCs (merchant cruisers) like Atlantis....:eek::eek:

I'm sensing you want them operating in company, tho. Bad idea. This exposes the catapult (supply) ships & their charges to destruction in detail all at once. Even rdv is a hazard; that's how a lot of the Type XIV boats were destroyed: the Allies broke the rdv cypher. Yes, you need better comm discipline, & for that, you need to get rid of Dönitz. (It was his idiot requirements that kept U-boats on the air with so much f*cking trivia so much of the f*cking time.:mad:) Either that, or you have to have a Brit POW reveal they were DFing his boats because they were on the air so damn much;:eek: the Germans didn't understand the Brits could do it. (They didn't dream the Brits could do it with shipboard DF:eek:...which the Brits had.:cool:)

For the supply ships, you really want "squirt" transmitters so they can send position & info reports to HQ, & let HQ re-radiate them.

Your proposed "depot ship" idea sounds good, but to make that work, you really do need friendly harbors; doing refits at sea is pretty ridiculous.

Impact on the war? Stunning.:eek::eek: You could shut off supplies to SU & Malta.:eek::eek: Cripple convoy routes around the Horn into North Africa.:eek: Massacre tanker convoys.:eek: (Which could cripple Bomber Command ops, for a start.:eek:) And increased Brit shipping losses anywhere means potentially very serious political consequences: the '42 losses forced Britain to shift from supplying Bengal to supplying Britain, which produced famine in Bengal/India. (Don't recall which.) If this happens sooner, or more than once, it risks a political crisis.

Germany doing better also means better chance of other countries joining her. Iraq? Iran? Japan moving against Southern Indochina sooner?

More U-boats off Canada also means more chance of U.S. involvement, as USN DDs are shot at, & sunk, & shoot back.:eek: (If you keep a roughly OTL schedule, when Hitler does declare on the U.S., *Paukenschlag is liable to be a massacre of Biblical proportions, since it's likely to be 30-40 Type VIIs, & not just 9 lousy Type IXs.:rolleyes: Call it Unternehmen Donnerkeil?)

If the Brits are half smart, they immediately put 4-5 sqns of ex-Bomber Command Stirlings each in Newfoundland, Iceland, Bermuda, & the Bahamas. This forces U-boats to scramble out in deeper water, where convoys are harder to find. (Newfoundland especially: keep U-boats from finding them as they form & sail, you keep them away from the patrol lines. With RCAF crews, & ASV radar, they could make a huge dent in the ability of U-boats to intercept convoys.) The Brits can, should, also immediately adopt the MAC ship, converting oilers & bulk carriers to operate 3-4 TSRs or 1-2 TSRs & 1-2 Martlets. They should also immediately give ASV radar (up to H2S standard) to Coastal Command. Circumstances forcing the Canadian government, or Britain, or Newfoundland, or all 3, to set up a major refit/repair base in St John's would be damn smart, too. (Losses in the all-RCN-escorted slow convoys are still going to be horrendous, & I see no hope of getting RN to turn over DDs & crews to RCN command, so improved protection is unlikely; RCN inability to operate more DDs {for lack of crews} means giving fast convoys to RCN is impossible.)

If the response is the same as OTL...:eek::eek::eek::eek: In that case, the increased losses are bound to lengthen the war. They make Torch unlikely until at least '43. They make Avalanche lunatic. They make *Overlord in '44 improbable, if not impossible. They dramatically increase the chances of the Bomb being used in Europe.:eek: And they create very, very good chances of the Brits doing something stunningly stupid (considered in summer '43 OTL, after U-boats had essentially been defeated:eek::confused:): abandon convoy.:eek::eek::eek::eek: Do that, IMO, all bets are off.:eek:
 
Top