Pre-WW1 Cruise Liners

[ArmchairSamurai]

Hello all,

Curiously, while I was tracking down all the cruise liners of the interwar in Germany, including those earmarked for carrier conversion, I came across a good number of pre-Great War cruise liners that were either seized in American waters in 1917 or taken as war booty by the Entente in 1918. Then a thought occurred to me: if Germany was allowed to keep said cruise liners, would then the surplus of ships, if given the incentive in the buildup prior to war in 1939, allow the Germans to command at least a handful of light aircraft carriers by 1940? Realistically the production would be rushed, and leave half of the line unfinished by the time war breaks out.

I will point out that it's entirely possible that many of the ships I have in mind might not be capable of conversion given that SS Europa was considered too weak for transatlantic voyages as an aircraft carrier if converted.

So far I know that the SS Scharnhorst became the IJN Shin'Yo, while SS Potsdam and SS Gneisenau were to become Elbe and Jade. The other interwar ships that I hold in consideration are SS General von Steuben, SS Vaterland, SS Deutschland, SS Cap Arcona, MS St. Louis, SS Bremen, MS Milwaukee, and SS Hansa. I figure I probably missed a few.

I am still tracking down the pe-WW1 cruise liners.

What do you all think?

[Peter89]

Hello all,

Curiously, while I was tracking down all the cruise liners of the interwar in Germany, including those earmarked for carrier conversion, I came across a good number of pre-Great War cruise liners that were either seized in American waters in 1917 or taken as war booty by the Entente in 1918. Then a thought occurred to me: if Germany was allowed to keep said cruise liners, would then the surplus of ships, if given the incentive in the buildup prior to war in 1939, allow the Germans to command at least a handful of light aircraft carriers by 1940? Realistically the production would be rushed, and leave half of the line unfinished by the time war breaks out.

I will point out that it's entirely possible that many of the ships I have in mind might not be capable of conversion given that SS Europa was considered too weak for transatlantic voyages as an aircraft carrier if converted.

So far I know that the SS Scharnhorst became the IJN Shin'Yo, while SS Potsdam and SS Gneisenau were to become Elbe and Jade. The other interwar ships that I hold in consideration are SS General von Steuben, SS Vaterland, SS Deutschland, SS Cap Arcona, MS St. Louis, SS Bremen, MS Milwaukee, and SS Hansa. I figure I probably missed a few.

I am still tracking down the pe-WW1 cruise liners.

What do you all think?

SS Gnisenau (18,160 GRT) is not a pre-WW1 ship, it was built in 1935. SS Potsdam (1899, 12,835 GRT) is different than SS Potsdam (1935, 19,121 GRT). The SS Scharnhorst, Gnisenau and Potsdam (of the 1935 year) are sister ships btw.

The Japanese rebuilt the Scharnhorst as an escort carrier and probably that's what it could do. The fundamental problems would be the lack of speed and escorts. Just think about a Royal Navy squadron made of light cruisers and destroyers closing in on a light carrier of this sort with 50% more speed. If they could close 150 nm during one night, by the time the Germans wake up, they are in the crosshairs of fast maneuvering, easily replaceable ships with no escorts to provide them any kind of cover and no speed to shake off the chasers.

It is no coincidence that all German commerce raider ships - including the Graf Zeppelin - were built to be able to steam at 28-32 knots.

[Takao]

1. The only way Germany keeps her ocean liners is if she wins. Which is it's own deeper rabbit hole

2. Realistically, the liners were already getting old, most were completed by the turn of the century. So, they would have already been scrapped, or were rusting away waiting to be scrapped.
Further, it would cost far more to bring them up to modern standards, as they would have to be gutted and everything replaced.

3. None of the German liners you have mentioned are pre-WW1 ships...All are post-WW1 new construction.

4. Giving the Luftwaffe-Kriegsmarine infighting, nothing would be done regardless of pre- or post-WW1 liners. For instance, name one German aircraft carrier that was operational during WW2.

[ArmchairSamurai]

SS Gnisenau (18,160 GRT) is not a pre-WW1 ship, it was built in 1935. SS Potsdam (1899, 12,835 GRT) is different than SS Potsdam (1935, 19,121 GRT). The SS Scharnhorst, Gnisenau and Potsdam (of the 1935 year) are sister ships btw.

3. None of the German liners you have mentioned are pre-WW1 ships...All are post-WW1 new construction.

Hey Peter89 and Takao! My honest mistake, I should have clarified better when I stated that the **interwar** ships I knew were the following (...), so there wasn't any confusion. I did say I was still tracking down pre-WW1 ships, but that was probably taken out of context given everything else I said. Oops! I know the interwar ships (most of them, I have since found more), not the pre-WW1 ships. Let's put that aside.

Good points all around regardless:

The Japanese rebuilt the Scharnhorst as an escort carrier and probably that's what it could do. The fundamental problems would be the lack of speed and escorts. Just think about a Royal Navy squadron made of light cruisers and destroyers closing in on a light carrier of this sort with 50% more speed. If they could close 150 nm during one night, by the time the Germans wake up, they are in the crosshairs of fast maneuvering, easily replaceable ships with no escorts to provide them any kind of cover and no speed to shake off the chasers.

Very true, so this eventual reality would likely see them bottled up in the North Sea or in the Mediterranean once the Bismarck, Tirpitz, and Scharnhorst / Gneisenau are sunk or damaged for extended periods if the carriers themselves haven't suffered the same fate. I am under the impression that any carriers fielded by the Kriegsmarine would be accompanied by said battleships, no? Now regarding this scenario, I am simply drawing up a "Happy Time" period of success like the U-boats enjoyed early on, only for the surface ships. I am not looking for anything war-winning by any means. Consider it a discussion.

2. Realistically, the liners were already getting old, most were completed by the turn of the century. So, they would have already been scrapped, or were rusting away waiting to be scrapped.

Ignore the Versailles Treaty for a moment, why not then have said cruise liners be the basis for a Weimar study into the feasibility of aircraft carriers? There was no mention of aircraft carriers being prohibited in the treaty to my knowledge but considering the limitations put on aircraft production, then perhaps once the Military Inter-Allied Commission of Control ceases to exist in 1927, things might move ahead. Correct me if I am wrong here. The Weimar did rearm, albeit secretly, in the years up to the 1933 election, just not to the extent the Nazis did. All that being said, this could be the groundwork the Kriegsmarine needed for future development, if anything else, similar to the experience Japan gained from Hosho in the 20s. Not much, but enough to prove feasibility and utility of the concept.

4. Giving the Luftwaffe-Kriegsmarine infighting, nothing would be done regardless of pre- or post-WW1 liners. For instance, name one German aircraft carrier that was operational during WW2.

That is why I said if given the incentive in the buildup prior to the war. What that incentive is, I have no clue. This is AH, after all, and this discussion is open to speculation. You are correct about the infighting. Then perhaps experience gained from the Great War would suffice, say if the aircraft carrier conversion of Ausonia actually commenced, and let's take this a little further to say a second Battle of Jutland in the latter half of 1918, gave said ship an opportunity to see action. Something of the sort is not too hard to fathom. Combine that with what I mentioned earlier about a late Weimar test-bed platform ala Hosho, and that could be more than enough to catch attention and convince Hitler (or whoever) of its importance.

Again, this is speculation, but interesting nonetheless. I am sure my ideas will be shot down, but eh, I like to see how people poke holes in my ideas.

[Takao]

Aircraft Carriers were warships and prohibited as per...
ARTICLE 190.

Germany is forbidden to construct or acquire any warships other than those intended to replace the units in commission provided for in Article l81 of the present Treaty

[Peter89]

Well if I stretch my imagination, the Germans could put through even far slower vessels through the Denmark Straits with fairly good chance, and of course they could send these theoretical carriers out into the Atlantic before the war began. I'd skip the latter possibility because between 1939 September and 1940 July the French navy also patrolled the seas and the Italians were neutral so that's exactly zero bases and 150% or more enemy patrols.

Up until the US joined the war there might have been a window of opportunity to cause some damage. But the problem is that still one destroyer could sink a carrier and recon flights could alert the enemy. The Admirality was great at cornering escaping commerce raiders, although their reputation was overrated after the lucky sinking of the Bismarck. After 1941 May the fleet became pinned down because it could not get new, proper bases and / or air cover. If the Bismarck didn't sink or there was extra carriers, they could only operate from either Norway / Germany, risking an unsafe passage through the Denmark Straits or from the French Atlantic coast, subjected to RAF attacks. All told the Germans could utilize anti-shipping units from land bases much, much more than from aircraft carriers.

[Takao]

Very true, so this eventual reality would likely see them bottled up in the North Sea or in the Mediterranean once the Bismarck, Tirpitz, and Scharnhorst / Gneisenau are sunk or damaged for extended periods if the carriers themselves haven't suffered the same fate. I am under the impression that any carriers fielded by the Kriegsmarine would be accompanied by said battleships, no? Now regarding this scenario, I am simply drawing up a "Happy Time" period of success like the U-boats enjoyed early on, only for the surface ships. I am not looking for anything war-winning by any means. Consider it a discussion.

Yes, the carriers were to have operated in conjunction with the Battleships to form the 2 battle groups Raeder wanted.
However, AFAIK, these conversions would be too slow to operate with the fleet(although I have not looked at all liner speeds). Even the Japanese Hiyo & Junyo were considered too slow to operate with the fleet until the devastating loss at Midway forced the Japanese to use them as fleet carriers. Better to have purpose built carriers that are meant to withstand the rigors of being "run hard."

Ignore the Versailles Treaty for a moment, why not then have said cruise liners be the basis for a Weimar study into the feasibility of aircraft carriers? There was no mention of aircraft carriers being prohibited in the treaty to my knowledge but considering the limitations put on aircraft production, then perhaps once the Military Inter-Allied Commission of Control ceases to exist in 1927, things might move ahead. Correct me if I am wrong here. The Weimar did rearm, albeit secretly, in the years up to the 1933 election, just not to the extent the Nazis did. All that being said, this could be the groundwork the Kriegsmarine needed for future development, if anything else, similar to the experience Japan gained from Hosho in the 20s. Not much, but enough to prove feasibility and utility of the concept.

As stated, warship construction was prohibited.

To do otherwise, you really have to twist history...
The WW1 carrier conversion was completed.
However unlikely, the Germans were allowed to keep it in the treaty.(Very doubtful considering the growing interest in carriers).

That is why I said if given the incentive in the buildup prior to the war. What that incentive is, I have no clue. This is AH, after all, and this discussion is open to speculation. You are correct about the infighting. Then perhaps experience gained from the Great War would suffice, say if the aircraft carrier conversion of Ausonia actually commenced, and let's take this a little further to say a second Battle of Jutland in the latter half of 1918, gave said ship an opportunity to see action. Something of the sort is not too hard to fathom. Combine that with what I mentioned earlier about a late Weimar test-bed platform ala Hosho, and that could be more than enough to catch attention and convince Hitler (or whoever) of its importance.

A second battle of Jutland would have been a death ride for the Germans...And what if the Ausonia was sunk or performed poorly? So, it really is a crap shoot as to the outcome.

Further arguing against this...Only the design was complete. Work still has to be done converting the ship. Then, the carrier has to be "worked up" and the crew trained. After that, you have to work up and train the air group(how many German aircrew ever operated from a carrier before). So, you are probably looking at late 1919 or early 1920 for the carrier to participate in a 2nd Jutland...Can Germany hold that long?

[ArmchairSamurai]

Aircraft Carriers were warships and prohibited as per...
ARTICLE 190.

Germany is forbidden to construct or acquire any warships other than those intended to replace the units in commission provided for in Article l81 of the present Treaty

Aha! Good point, I did not consider Article 190 in that context given that carriers were so new, yes. I was thinking more in the vein of loopholes, but you are right. So, what of the Weimar then post 1927? Would it still be feasible to start the conversion of a liner, say as an example the SS Vaterland (given she is not seized in American waters)? Better yet, why not then convert a civilian liner built by HAPAG or NDL during the Weimar era? The groundwork could be built without raising alarm, without aircraft, as merely a test lab for construction methods. It's a stretch sure, but something, given the Weimar's secret rearmament in the latter 20s. Furthermore, why not test the carrier (in Soviet waters) per the Treaty of Rapallo (1922) as done with early panzers? I am sure the USSR would be interested in learning from such experiments, and although it would come back to bite the Nazis after they come to power, its no different than the experience gained by the Soviets IRL in the Treaty of Rapallo anyway, only now it's expanded to include ships.

Well if I stretch my imagination, the Germans could put through even far slower vessels through the Denmark Straits with fairly good chance, and of course they could send these theoretical carriers out into the Atlantic before the war began. I'd skip the latter possibility because between 1939 September and 1940 July the French navy also patrolled the seas and the Italians were neutral so that's exactly zero bases and 150% or more enemy patrols.

As I said in my OG post, I imagined that a Kriegsmarine carrier line, even if only two, being completed just as France falls in 1940 and right before the BoB, would be much more likely, no? Given the already stretched military-industrial complex and that a full war economy had not yet been implemented by Germany, I can see the work stretching out for several years, from the mid-30s possibly up into 1940, especially given the infighting that Takao mentioned earlier and with U-boat manufacture taking priority. If that is the case, the French navy would be essentially a nonissue no? Between the Attack on Mers-el-Kébir and whatever ships are seized by the Germans, or flee to Canada, the RN alone would have to take up the mantle by the time these ships become a factor.

However, AFAIK, these conversions would be too slow to operate with the fleet(although I have not looked at all liner speeds). Even the Japanese Hiyo & Junyo were considered too slow to operate with the fleet until the devastating loss at Midway forced the Japanese to use them as fleet carriers. Better to have purpose built carriers that are meant to withstand the rigors of being "run hard."

Another good point. But remember Germany is strapped, and I do not think any scenario without serious timeline meddling as you said, would change her having the ability to field purpose-built carriers in the beginning. You also have to consider that the experience in building / operating carriers would have to come from somewhere too. They would have to field underwhelming carriers if this scenario is to work for 1940. That leads me back to the Ausonia and the Weimar post-war:

A second battle of Jutland would have been a death ride for the Germans...And what if the Ausonia was sunk or performed poorly? So, it really is a crap shoot as to the outcome.

Further arguing against this...Only the design was complete. Work still has to be done converting the ship. Then, the carrier has to be "worked up" and the crew trained. After that, you have to work up and train the air group(how many German aircrew ever operated from a carrier before). So, you are probably looking at late 1919 or early 1920 for the carrier to participate in a 2nd Jutland...Can Germany hold that long?

I understand where you are coming from. A second battle of Jutland did not necessarily have to be a victory though, nor do I not think the Ausonia being sunk (or even her poor performance sea-wise) would be proof against interest in the concept back then. I see it more as merely wetting the feet of the military-minded in the potential of the carrier against the battleship fleet. Consider this in the sense of the naval arms race between Great Britain and Germany leading up to WW1, then the blockade of Germany, and finally Jutland. The concept of carriers could (and I will stress *in their mind*) render that all obsolete and give Germany an edge once more. Even under post-war restrictions, this mindset will still exist all the same as the desire for tank doctrine did; there was much to learn from Germany's experiences with tanks in WW1 and how the Entente fielded their own. Do you see what I mean?

You are right that Ausonia, if she was completed and lived to see the treaty, she would be confiscated by the Entente, save she is not scuttled in Scapa Flow by her crew. You are also right about the training required to make her feasible as a cohesive unit. Stretching the war to 1919 is not impossible, but not in the OTL. So there is some tweaking to be made there! I will add that the HMS Ark Royal, HMS Argus, and HMS Furious are exactly what I am describing when it comes to the Ausonia and lessons to be learned by the Kaiserlichemarine. Those lessons, passed down to the Weimar and with her own secret testing, combined with what is learned from Japan, might be enough to make this scenario work, even if the results are lackluster.

Up until the US joined the war there might have been a window of opportunity to cause some damage. But the problem is that still one destroyer could sink a carrier and recon flights could alert the enemy. The Admirality was great at cornering escaping commerce raiders, although their reputation was overrated after the lucky sinking of the Bismarck. After 1941 May the fleet became pinned down because it could not get new, proper bases and / or air cover. If the Bismarck didn't sink or there was extra carriers, they could only operate from either Norway / Germany, risking an unsafe passage through the Denmark Straits or from the French Atlantic coast, subjected to RAF attacks. All told the Germans could utilize anti-shipping units from land bases much, much more than from aircraft carriers.

I do not see this as a problem. It's a reality, which is fine. No one could have expected the war to turn out one way or another, and the RN ultimately being victorious is realistic. Again, I am not looking to make a war-winning scenario. This only adds up to a much greater AH timeline.

[Takao]

Aha! Good point, I did not consider Article 190 in that context given that carriers were so new, yes. I was thinking more in the vein of loopholes, but you are right. So, what of the Weimar then post 1927? Would it still be feasible to start the conversion of a liner, say as an example the SS Vaterland (given she is not seized in American waters)? Better yet, why not then convert a civilian liner built by HAPAG or NDL during the Weimar era? The groundwork could be built without raising alarm, without aircraft, as merely a test lab for construction methods. It's a stretch sure, but something, given the Weimar's secret rearmament in the latter 20s. Furthermore, why not test the carrier (in Soviet waters) per the Treaty of Rapallo (1922) as done with early panzers? I am sure the USSR would be interested in learning from such experiments, and although it would come back to bite the Nazis after they come to power, its no different than the experience gained by the Soviets IRL in the Treaty of Rapallo anyway, only now it's expanded to include ships.

Probably not the liners...As they will be revenue generators in the early 20's when Germany needs cash. Not to mention the prestige associated with the large liners. People will notice the Vaterland being taken out of service, especially the Naval folks.

Test lab for construction methods‽ the Germans already did that in WW1. They need to test with Aircraft to develop operational and tactical doctrine for aircraft carriers.

The Soviet Union flirted with the carrier in the early 1920's, going so far as to draw up plans to convert the training ship Komsolets(sp?) Into an aircraft carrier. However, the Soviets were not yet enamored with a blue ocean navy, and decided to restrict themselves to littoral naval forces. Land-based aircraft were to be the power in this arena. As such, the carrier, with it's small air group was seen as unnecessary. So, it would be unlikely that the Soviets agree to "training" a german carrier.

Another good point. But remember Germany is strapped, and I do not think any scenario without serious timeline meddling as you said, would change her having the ability to field purpose-built carriers in the beginning. You also have to consider that the experience in building / operating carriers would have to come from somewhere too. They would have to field underwhelming carriers if this scenario is to work for 1940. That leads me back to the Ausonia and the Weimar post-war:

I disagree...But, I think you are focused on large aircraft carriers.

Japan and Great Britain had no real experience building/operating purpose built carriers. Yet, Japan built the Hosho & Great Britain built the Hermes(both small purpose built carriers)...That is how they acquired their experience. Unfortunately the Treaty prevented Germany from constructing new warships.

I understand where you are coming from. A second battle of Jutland did not necessarily have to be a victory though, nor do I not think the Ausonia being sunk (or even her poor performance sea-wise) would be proof against interest in the concept back then. I see it more as merely wetting the feet of the military-minded in the potential of the carrier against the battleship fleet. Consider this in the sense of the naval arms race between Great Britain and Germany leading up to WW1, then the blockade of Germany, and finally Jutland. The concept of carriers could (and I will stress *in their mind*) render that all obsolete and give Germany an edge once more. Even under post-war restrictions, this mindset will still exist all the same as the desire for tank doctrine did; there was much to learn from Germany's experiences with tanks in WW1 and how the Entente fielded their own. Do you see what I mean?

It could be taken many ways...Germany could see it as necessitating more U-Boats to attack carriers or more long-range bombers to stop the British fleet. This goes to asymmetric warfare.

Further, the small aircraft that would be put aboard carriers at the time, were not seen as "game changers" capable of rendering Battleships obsolete.

There is a reason carriers were still fitted with large guns at the time.

You are right that Ausonia, if she was completed and lived to see the treaty, she would be confiscated by the Entente, save she is not scuttled in Scapa Flow by her crew. You are also right about the training required to make her feasible as a cohesive unit. Stretching the war to 1919 is not impossible, but not in the OTL. So there is some tweaking to be made there! I will add that the HMS Ark Royal, HMS Argus, and HMS Furious are exactly what I am describing when it comes to the Ausonia and lessons to be learned by the Kaiserlichemarine. Those lessons, passed down to the Weimar and with her own secret testing, combined with what is learned from Japan, might be enough to make this scenario work, even if the results are lackluster.

I would strike HMS Ark Royal from the list...The Germans already had seaplane carriers, even converting the cruiser Stuttgart into a seaplane carrier. Not to mention, Germany had her own civilian seaplane catapult ships.

As to lessons learned from Japan, they were the wrong lessons. Japan showed the Germans the "old" aircraft carrier, and not the one they were modernizing.

I do not see this as a problem. It's a reality, which is fine. No one could have expected the war to turn out one way or another, and the RN ultimately being victorious is realistic. Again, I am not looking to make a war-winning scenario. This only adds up to a much greater AH timeline.

The reality was meant for completion of much of the Z Plan. 2 battleship & carrier task groups were to operate and create openings for the U-Boats and/or surface raiders to attack convoys by drawing off the larger escorts. The German task groups were really not meant to take on the British fleet unless a favorable opportunity presented itself.

[T. A. Gardner]

The problems with converting ocean liners / fast merchants into carriers was one of an increasing separation between what those ships were capable of in terms of speed, along with their size, and suitability in terms of how much remodeling would be necessary.

Thus, in the 1920's converting an 18 to 25 knot merchant into a carrier launching biplanes wasn't much of a stretch. By the late 30's anything under around 25 knots was simply too slow to launch heavier, larger monoplanes. The same goes for hull size. Merchants didn't grow as fast as carriers in size.
Then there was the simple problem that merchant ship machinery was largely unsuited for military use as a carrier. A carrier's machinery was pushed harder. There was a need for greater amounts of electrical power for things like catapults and elevators, then electronics.
Throw in that you could no longer just raze the merchant to the main deck and plop a carrier on top because of the need for ordinance magazines, larger crew--you just got rid of most of the passenger space--elevator wells, etc., and the conversion becomes more one of gutting much of the hull along with the superstructure.
Seaplane "carriers"--more like tenders-- weren't nearly so complicated to convert, but then they couldn't be launching and landing masses of aircraft while underway in open ocean in many circumstances.

The liner / merchant conversion for a fleet carrier is really a bust by 1940. Such conversions from cheaper merchant hulls as CVE carrying say a 12 to 24 lower performance aircraft for secondary missions like ASW or amphibious support were a good buy, but they were no substitute for properly designed and built fleet carriers.

[ArmchairSamurai]

[...] I think you are focused on large aircraft carriers.

I never said that per se. I just thought converting cruise liners was an interesting hypothetical idea for the late Weimar, but I have come to realize otherwise.

Probably not the liners...As they will be revenue generators in the early 20's when Germany needs cash. Not to mention the prestige associated with the large liners. People will notice the Vaterland being taken out of service, especially the Naval folks.

Fair.

The Soviet Union flirted with the carrier in the early 1920's, going so far as to draw up plans to convert the training ship Komsolets(sp?) Into an aircraft carrier. However, the Soviets were not yet enamored with a blue ocean navy, and decided to restrict themselves to littoral naval forces. Land-based aircraft were to be the power in this arena. As such, the carrier, with it's small air group was seen as unnecessary. So, it would be unlikely that the Soviets agree to "training" a german carrier.

Fair. Would not be the most unrealistic thing, but for now, let's drop that.

Test lab for construction methods‽ the Germans already did that in WW1. They need to test with Aircraft to develop operational and tactical doctrine for aircraft carriers.

Good point, however, the construction design was not sound, which would warrent changes, no? That is what I meant. What I meant was a further development, a test lab for different ideas shipwise (as you touch upon later)... What could need improvement, what needs to be redesigned, what are other nations experimenting with, etc., based on what little experiences they did get. The Ausonia is a conversion after all, not purpose-built, so maybe that is the nudge that moves them to reconsider previous carrier notions and start from scratch rather than to look for a suitable civilian ship. Or follow the US example of Lexington and Saratoga perhaps? Having the aircraft available is a must of course, with things like arresting gear and elevators not being developed without them, nor can takeoff and landing exercises be conducted. I get that. I am simply going about the Weimar building (just) a ship secretly, which I have already stated.

Japan and Great Britain had no real experience building/operating purpose built carriers. Yet, Japan built the Hosho & Great Britain built the Hermes(both small purpose-built carriers)...That is how they acquired their experience. Unfortunately the Treaty prevented Germany from constructing new warships.

That's what I was getting at... I did not say Japan and Great Britain had any worthwhile experience in building/operating carriers in the early days. What I was trying to get across is that they were doing *something*, and something is an incentive for action, as to why I pointed out the comparison with the naval arms race. Know your enemy. Learning curves are important, even if they are not realized yet and that is what Great Britain and Japan can offer (not literally offer of course). And yes, I know, as we have already confirmed, that the treaty denounced the construction of new warships (including carriers). I will state again, this is secret. Yet this seems to be an issue I cannot as of now figure out, which is why such discussions are important to world-building in AH scenarios. The Nazis can do secret projects under the nose of the other nations through secretive means, but hiding a ship is another thing pre-1935, as Emden was laid down in 1921, and her design was heavily influenced by the treaty. Unless the Weimar, before the Nazis take power, follow the same approach, in open defiance of the treaty as they were already doing secretly with other projects. That's a big stretch because when is the big what if, as is leadership. What year is best for the former Entente to not react to such a brazen act of provocation--is it even possible pre-Nazi takeover or was appeasement exclusively to satiate the new power in Germany? If nothing else, why not just design work? Why not design a new carrier, nothing spectacular by any means, but a purpose-built carrier based on what knowledge and experience are available?

It could be taken many ways...Germany could see it as necessitating more U-Boats to attack carriers or more long-range bombers to stop the British fleet. This goes to asymmetric warfare.

That's up for debate, very true. I will argue that more submarines would not be the lesson taken from Ausonia. Submarines can harass a fleet yes, deny merchant shipping, yes, however you never put all your eggs in one basket, from a stragetic point of view. Submarines played a big role for Germany in WW1, as commerce raiders and blockade runners, yet while very successful, the enemy developed countermeasures that prevented total supremacy. Once aircraft carriers were introduced as a concept, every nation with a fleet experimented and invested (aside from the USSR as you pointed out), same as tanks and even semi-auto rifles (though concepts like the latter took much longer to come to service, which I will elaborate more on later). Weapon diversification and development are key to war. OTL WW1 experiences saw rapid development in submarine design in addition to their strategy/tactics just how I suggest the introduction of an early carrier would do. They go hand in hand.

Long-range bombers are another matter (an altogether different rabbit hole OTL given Goering, Udet (others), and without Weaver or Wimmer) as I doubt more Condors would be a priority before 1940 given Luftwaffe production numbers, nor would any heavy bombers come to exist to fill such a role as noted with who is calling the shots; in addition, Fliegerführer Atlantik did not exist prior to late 1940 anyway, as its origin, to my knowledge, owes its existence to new bases available only after the fall of France and Norway. That being said, if such planes did come to exist in the build-up to WW2, they would likely be coupled with the surface fleet all the same as the zeppelins were for scouting in WW1. So, you make a good point, but that only complicates matters further.

Besides, a few carriers are not matching blow for blow with the RN anyway. The Kriegsmarine understood that, carriers or no carriers. They had no capacity to build a fleet to match the RN for some time, time they could ill afford.

Further, the small aircraft that would be put aboard carriers at the time, were not seen as "game changers" capable of rendering Battleships obsolete.

You are missing the point. Those particular aircraft at that moment were not game changers, you are absolutely correct, but the idea had the potential to be. Do you think anyone immediately thought after the invention of the airplane: we can drop bombs from this? Universally, (a) military does not adopt a weapon or system because literally everyone suddenly realizes how valuable it is, no, it takes an individual, or sometimes more, to convince brass to invest. No one entered WW1 with tanks, nor fighter/bomber aircraft, and both concepts (including others) were initially overlooked by the same conservative brass who still clung to the idea of the calvary will always break through. It took decades of development for most nations to adopt semi-auto rifles, even if they existed for use in WW1. Even using airplanes as reconnaissance was not initially recognized, but its value was validated in that role following the Italo-Turkish War a few years prior. It took some pioneering men to push concepts, demonstrate them, sometimes pay for them out of pocket and even configure them in the field for use before they caught on and became official. Thus such concepts were further developed. It does not take much to imagine something, but it takes a lot to make that something a reality, more to be adopted by a major military power. War is always changing just as the weapons with which it is waged.

There is a reason carriers were still fitted with large guns at the time.

And? That's just a hallmark of early carrier design indicative of heavier defensive armaments; that has nothing to do with the planes or any perceived lack of trust in their effectiveness. No side can guarantee their carrier will not meet enemy warships within range, especially if they are expected to operate under a screen, under inclement weather, or at night. So, early carrier design reflected that. Just to demonstrate, during Fleet Problem IX (an exercise devoted to fleet carrier action around Panama), Saratoga was "sunk", while Lexington was ruled to be "heavily damaged" (if only to keep her in the exercise), with both attacks being made by battleships. And as weapons evolution goes, the downsides of such arrangements on carriers became apparent, and eventually, they were removed in favor of longer runways, more space, and more AA (among other design choices).

The reality was meant for completion of much of the Z Plan. 2 battleship & carrier task groups were to operate and create openings for the U-Boats and/or surface raiders to attack convoys by drawing off the larger escorts. The German task groups were really not meant to take on the British fleet unless a favorable opportunity presented itself.

I am aware of the long-term plan, yes. Ideally, that would be more interesting to see, but I am repeating myself ad nauseam if I say again that I am not aiming to defeat the RN, and since you brought it up, nor to see Z plan come to fruition. The timetable for both is not possible, as I have already touched on. I merely want to give the Kriegsmarine a few operational carriers by 1940, given what the OTL can afford me. Bismarck and Prinz Eugen traveled together in a pair, so let's add a carrier or two to the operation. Does that add unforeseen factors? Of course. But without completely rewriting everything, I do not have much else to work with.

I will reframe from trying to suggest more ideas, but instead, I will ask you what ideas you have. Thoughts?

[ArmchairSamurai]

The problems with converting ocean liners / fast merchants into carriers was one of an increasing separation between what those ships were capable of in terms of speed, along with their size, and suitability in terms of how much remodeling would be necessary.

Thus, in the 1920's converting an 18 to 25 knot merchant into a carrier launching biplanes wasn't much of a stretch. By the late 30's anything under around 25 knots was simply too slow to launch heavier, larger monoplanes. The same goes for hull size. Merchants didn't grow as fast as carriers in size.
Then there was the simple problem that merchant ship machinery was largely unsuited for military use as a carrier. A carrier's machinery was pushed harder. There was a need for greater amounts of electrical power for things like catapults and elevators, then electronics.
Throw in that you could no longer just raze the merchant to the main deck and plop a carrier on top because of the need for ordinance magazines, larger crew--you just got rid of most of the passenger space--elevator wells, etc., and the conversion becomes more one of gutting much of the hull along with the superstructure.
Seaplane "carriers"--more like tenders-- weren't nearly so complicated to convert, but then they couldn't be launching and landing masses of aircraft while underway in open ocean in many circumstances.

The liner / merchant conversion for a fleet carrier is really a bust by 1940. Such conversions from cheaper merchant hulls as CVE carrying say a 12 to 24 lower performance aircraft for secondary missions like ASW or amphibious support were a good buy, but they were no substitute for properly designed and built fleet carriers.

Very good points Gardner! Thank you for pointing that out.

[Carl Schwamberger]

Aircraft Carriers were warships and prohibited as per...
ARTICLE 190.

Germany is forbidden to construct or acquire any warships other than those intended to replace the units in commission provided for in Article l81 of the present Treaty

What about a fast commercial 'airport ship'. Set up the service fast mail transports crossing the north and south Atlantic & Zepplin type aircraft? Luxury cabins for folks laying over waiting for connecting flights? Not warship here folks, just a ultra modern commercial seagoing ship

[Takao]

Aircraft Carriers were warships and prohibited as per...
ARTICLE 190.

Germany is forbidden to construct or acquire any warships other than those intended to replace the units in commission provided for in Article l81 of the present Treaty

What about a fast commercial 'airport ship'. Set up the service fast mail transports crossing the north and south Atlantic & Zepplin type aircraft? Luxury cabins for folks laying over waiting for connecting flights? Not warship here folks, just a ultra modern commercial seagoing ship

Germany already did that with her 4 civilian seaplane catapult ships during the 1930's. Although, they were not "fast", about 16 knots or so.

Zeppelin did not need the airport ship, as they had plenty of range to go the entire distance.

[Carl Schwamberger]

I was joking there...

Zeppelin did not need the airport ship, as they had plenty of range to go the entire distance.

In that case I was thinking of a layover site for passengers to change flights.