Sid Guttridge, Welcome back for another "kick at the proverbial cat" ! Lots of research done this time too. Excellent.
The first and main objection to the operation is that, if compromised, it would alert US forces everywhere and very possibly modify the outcome at Pearl Harbour. The Japanese would first have to decide whether such a speculative risk to their primary objective – the annihilation of the US Pacific Fleet – was worth it. - Sure but the OTL Japanese attack was already the biggest risk of that discovery. If somehow intercepted or spotted then my ATL
Chitose is "hiding in plain sight". Until late on the afternoon of Dec.6'41 she wouldn't be doing anything except her previously publicized voyage towards Argentina. Her numerous single engined floatplane scout aircraft should be able to report any threats to her long before those threats could catch a glimpse of an "off course"
Chitose. Even if somehow spotted after dark in Galapagos waters she could claim "engine trouble" or "a burst crewman's appendix emergency" etc.etc. until she determined the threat level. If great then she says "sorry" and turns around to go back home, with no harm, no foul being done. If minor then she and her 3 SS escorts might very well decide to use force to deal with the threat. Long distance communication with 1941 radio gear was not nearly as reliable as the satelite phones of today make it.
As the voyage of the Chitose would be flagged up publicly in advance, the US might choose to alert its defences in Panama. After all, it had already stopped the passage of Japanese merchant ships through the canal in July 1941 through fear of sabotage, so it was clearly sensitive to the Japanese threat. - Possibly but with my ATL
Chitose scheduled to pass by so far away from Panama, why would they do so ? Sure, American RDF posts might track her position based on her regular daily radio broadcast but they would have no way to know that at some point those broadcasts were taken over by an IJN submarine now carrying the
Chitose's regular radio operator, on her originally published course. "Hiding in plain sight" using the same radio deception methods used by the OTL KB prior to their attack on Pearl Harbor.
Argentina first had to be persuaded to buy the Mavis. In December 1941 it was still high on the list of countries allocated Lend Lease by the USA. Indeed, after Brazil, it had the second highest allocation in Latin America and, amongst many other requirements, wanted eight US PBY-5 Catalinas to replace the US P2Y-3As it had in service. Lend-Lease offered aircraft at about one third the normal price. To undercut that, the Japanese would have to offer a suspiciously sweet deal that would probably have to cover numerous other items on Argentina’s wish-list as well. _ IIRC the source that I listed mentioned that a barter trading deal had been set-up between Japan and Argentina in 1940 so no cash need have changed hands at all. And what better way for Argentia to extract a lower priced deal from the eager Americans than to show them that there was another "player" available that was wiling to provide modern military equipment ?
You obviouslt intend to take this to a level of detail that I had not anticipated nor researched but such is my own responsibility for raising the point in the first place. I am grateful for the challenge however so please, carry on ...
Why would the Mavises plausibly be delivered by sea? They were presumably being marketed as long range maritime reconnaissance types. The US, the Italians, the French and Germans all had scheduled air services to Latin America, the latter three across the Atlantic. The US had scheduled trans-Pacific flyingboat flights. The US had apparently not banned overflights by Japanese aircraft as the proposed record-breaking Tokyo-New York-Buenos Aires flight by the Tachikawa Ki-77 indicates. The US P2Y-3As had been delivered to Argentina by air in the mid 1930s. Would not the delivery of the Mavises by sea be inherently suspicious, besides calling into question their performance? - Perhaps my logic at the time is best illustrated by analogy ? If you were to go out tomorrow and purchase a new Volkswagon "Beetle" automobile, would you prefer that it be driven to you all the way from it's factory, in Mexico, on it's own 4 rubber tires or would you prefer that it arrive in brand new and unworn condition on the back of a car transport truck, after a long railwaycar ride ? In my own case, I would choose the later delivery method but "your mileage may vary". Would such an arrival by transport truck cause you to doubt the ability of that car to carry both you and your family members safely "down the road" or would you think a wise choice instead ?
The Mavis was also apparently exceptionally vulnerable to fighters, as it lacked self-sealing fuel tanks or armour protection for the crews. They would therefore have been absolutely dependent on secrecy. They could probably not “fight through”. - Yes. As I believe that I previously explained in another posting here, the 3 Japanese Mavis pilots would be expressly trained and ordered to NOT try to "fight their way through" if discovered, at least until the last possible seconds. The secrecy of the Pearl Harbor attacks might very well DEPEND on any one of those 3 aircrews maintaining their Pan-Am bluff for as long as was humanly possible. They would be told that even the humiliation of capture and surrender would earn the gratitude of the Empire and indeed, of the Emperor himself.
I think you may be confusing the large Japanese population in Peru with the small one in Ecuador. The Galapagos Islands were, as you post, Ecuadoran. Ecuador was apparently hostile to Japan at this time: “Japan, indeed, had long been a bug-bear on the Pacific coast and was especially obnoxious in Ecuador because Japanese textiles undercut Ecuadorean. Besides anti-Japanese demonstrations in June, 1940, there had been press campaigns against Japanese competition in both August, 1940, and in April, 1941” (p.121, Latin America and the Second World War, 1939-1942. by R. A. Humphreys.) Thus Ecuadoran hostility was very likely. - I can't claim to have yet put as much research time into this issue as you obviously have but I also don't recall ever claiming that the Ecuadorians would be inviting my ATL Chitose into their Galapagos waters ? "The Galapagos Archipelago consists of 7,880 square km (3,042 sq. miles) of land spread over 45,000 square km (28,000 miles) of ocean ... The group consists of 13 main islands, 6 smaller islands, and 107 rocks and islets." comes from
http://en.wikipedia.org/wiki/Galapagos_Islands and indicates my belief that it would not have been too difficult for a Japanese seaplane tender to locate a suitably sheltered and hidden anchorage (in case of stormy weather) within that scattered group from which to refuel and launch her 3 Mavis, unmolested. While watched over by a tanker and at least two IJN submarines and her own flock of single engined floatplanes.
Nor were the islands unpopulated. Albermarle Island had a population of 600 and at least three more had populations in the 100s. Their main occupation was fishing, making clandestine maritime activities difficult. There was also a small Ecuadoran naval garrison that was normally sustained by the aviso Eloy Alfaro on monthly visits. Her schedule would have to be ascertained. - As would her usual night time route thru the island group which as I have already posted consisted of "13 main islands, 6 smaller islands, and 107 rocks and islets" that were spread out over some 28,000 sq. miles of ocean. With that large of an area for just one monthly ship to search, I'm not too worried about Ecuadorian discovery just yet.
Attention had also recently been drawn to the islands by the activities of the German raider HSK7 Komet, which had sunk or captured two or three Allied merchantmen near them in mid August 1941. - Do you have proof of any Allied searchers still remaining in the area as late as Decemeber 6'41 or do you attempt to foster doubt thru suggestion alone ?
And then, of course, there is the imponderable weather. “A calm open water takeoff” was by no means guaranteed. - Which is why my initial posting of this thread contained the sentence, "On the evening of Dec.6'41 she (and her 3 IJN submarine escort) would quietly anchor instead in a deserted lee bay somewhere in the numerous Galapagos Islands, which were owned by Ecuador." Just in case the weather demanded a calm lee shore for Mavis takeoffs.
But, if the weather was a factor in the Galapagos, why take the risk of using them anyway? What is wrong with the open sea? Greater secrecy could be traded off for greater dependency on weather conditions. - Uhmm, the possiblity of big winds and bigger waves. Without accurate weather forcasts that far out from Panama, the risk of a sudden unexpected storm would be too great a risk to the entire mission.
The planned 1945 attacks on the canal was to be by submarine-borne aircraft launched from the open sea. - IIRC the I-400 class IJN submarines were intended to use their foredeck mounted catapult to launch their 3 single engined floatplane bombers, one-by-one. Not the open ocean surface beside those surfaced submarines.
Due to the time difference with Hawaii, the approach would have to be in broad daylight. - As did the Pan-Am China Clippers that they would attempt to impersonate. I'd imagine that with mechanical issues, storms and headwinds those Pan-Am flights would not be anything near to always being "on schedule".
With its thin, detached body, the Mavis does not look much like the Pan-American Clippers, even if marked like them. - Considering the persistant rumor that the Mavis's design was based on the Sikorsky S-42 "China Clipper" design I find your assertion to be surprising. My initial posting for this thread contained two photo URLs for comparison by my readers. I think that the two do indeed look much alike. Pan-Am's minimalist marking can be seen there also.
(When were these markings to be applied?) - The main paint job would be factory applied before departure from Japan but the round painted on side windows and small Pan-Am specific markings would only go on once near the Galapagos.
Furthermore, if the Clippers did not normally fly in at the same time as the attack, the very timing would be suspicious. Splitting up into three independent flights triples the likelihood of being spotted because it increases the numbers of observers, so more might be lost than gained by this. It also makes coordination over the target problematical. An early arrival by one might compromise the others. - Au contraire, since China Clippers flew their routes alone, a flock of three flying together would be sure to attract notice. A 2 Clipper rendezvous over an island at the far end of Gatun Lake could be explained to any curious control tower radioman as a meeting to exchange fragile engine repair parts, with the torpedo attack to begin instead as soon as the 3rd arrived.
In fact I still debate with myself on the idea of having each Mavis also carry a rubber raft or two to be filled with waterproof explosives and an IJA demolitions team trained to further disable the water holding abilites of the Panama Canal's water storage lakes. Each fake "China Clipper" could land in an isolated bay and discharge it's "commando team" before taking off again to complete it's twin spillway torpedo run(s). The 3 biggest problems being that AFAIK the early war OTL Japanese didn't use small unit commando tactics below paratrooper battalion size, the risk of damaging a flyingboat on unseen debris (or an alligator/crocodile of which there were plenty of both) and my review of the design drawings of most of the Panama Canal's dikes. None so far seem to be vulnerable to the quantites of explosives that could be placed without very bukly and heavy (& noisey) drilling equipments.
The US defences of the Canal were vulnerable in many areas, but had improved markedly since 1939. For example, the number of anti-aircraft battalions (manned by the coastal artillery, if I remember correctly) had been doubled. The fact that neither you nor I know exactly where they were deployed cannot be taken to mean that the spillway gates were not covered. If you can conceive of attacking them, it is entirely possible that the US command could conceive of defending them. Although not comprehensive, there were naval patrols by SEPAC, regular aerial reconnaissances by Army and Naval aircraft, some radar cover, some fighter defence and some anti-aircraft artillery defence. Certainly they were not fully effective, but any attack could have been tripped up on any one of them. - No doubt. But then I have already presented the official written opinions of the US military on the qualities of the Dec. 1941 defence capabilty in Panama. And summed it up in my first posting for this thread with:
"THUS IT IS REVEALED THAT THE PRIMARY US PACIFIC DEFENSE OF THE PANAMA CANAL IN DECEMBER 1941 RELIED SOLELY ON THEIR MERE HOPE THAT THE JAPANESE WOULD NOT ATTACK THEM ANYTIME SOON !!!"
I see no proof from you yet that this American military opinion is/was incorrect. If their own commanders wrote this then just imagine the real state of those American defenses.
Just as any one of probably a hundred events might have tripped up the OTL Japanese attack on Pearl Harbor. Yet those OTL Japanese attempted it anyway, to spectacular success. They were adaptable, bold, confident and resourceful, not to mention aggressive. My ATL Panama Japanese would embody the same "we'll do it for the Emperor" attitude.
In this instance, I don’t think the shortage of 37mm AA ammunition would have been very significant. Your scenario foresees only one attack by three rather large, lumbering aircraft, presumably in quick succession. 37mm AA would have been lucky to have a target for a minute. - Other than your unsupported opinion, what proof do you offer that any US AA gunners at all, let alone their AA guns, were deployed in their seats with ammo loaded and ready to fire for that 1 minute, anywhere within range of the Gatun Spillway or of the probable torpedo release points out over Gatun Lake ?
What would possibly cause US Army gunners to shoot down what apppeared to be peacetime civilian Pan-Am China Clipper flyingboats out over Gatun Lake ? Especially when those Americans have no knowledge that Japan had developed, tested and deployed a shallow water launched torpedo modification ?
Other than a distressing incident involving an Iranian civilian airliner a few years ago out over the Persian Gulf, I was not aware that such deliberate civilian butchery was US military policy either now or back in 1941 ??
And what about all the other calibers? - Since none were mentioned in a derogatory fashion in the American reports that I have already presented then I would imagine them to have workable quantiies of ammunition. Were they alert and ready to fire instantly on civilian targets in peacetime, is not mentioned so I can only guess, no.
In the final analysis, what probably scuppers this operation, besides a complexity that leaves numereous hostages to fortune and the threat its exposure posed to the far more important Pearl Harbour attack, is that it could be foiled by a very cheap, low-tech device – a torpedo net. - In your final analysis that is. As previously mentioned, why would the 1941 Americans install anti-torpedo netting to prevent a torpedo attack in such shallow water ? If they didn't deploy atn to protect their own Pacific Fleet from a devastating attack in it's own home port, several thousnad miles closer to Japan than Panama was, then why would they deploy it at the Gatun Dam ? Other than your own fore-knowledge of my ATL Panama attack proposal that is ? Mention is made of anti-torpedo netting being deployed pre-PH to defend all 4 of the Canal entry lock gates at both the Caribean and Pacific ends of the Canal but there is no mention of similar at Gatun.
I would suggest that the Japanese would have been foolish to risk compromising their attack on the US Pacific Fleet in Pearl Harbour in the hope that the USA had not spent a pittance on such a widely used defensive device as a torpedo net at Gatun spillway. This operation is only a starter if (1) there were no torpedo net and (2) the Japanese knew this for a fact. Do we know either ? - Not at this time but I can easily refer you to the method available to the 1941 Japanese for providing both. A look at
http://www.ibiblio.org/pha/pha/magic/x12-0022.html will show the Panama origin MAGIC intercepts by American intelligence. I do not know if this URL lists all or just some of the intercepts nor what percentage of all such OTL Japanese transmissions from Panama were intercepted. Even without that knowledge however it is quickly apparent that the Japanese operatives on the ground in Panama were very good at their intell gathering tasks and could have easily collected and forwarded to Japan almost any information required. A simple fishing trip to Gatun Lake just a couple of days prior to Dec.7'41 would have revealed the presence of US anti-torpedo netting at the Gatun Dam spillway to Tokyo as well as the locations and readiness status of any American AA defences installed around it.
And remember – absence of evidence for a torpedo net is not evidence of the absence of a torpedo net. The same goes for AAA defences, etc. - I disagree. While you are entitled to your own opinion, you require a ridiculous standard of proof which no ATL could ever hope to satisfy. How can one prove what never happened ? An ATL can only delve into the plausibility or probable likelyhood of an imaginary event.
For confirmation something more reliable and in depth than an internet search is probably necessary. - Why don't you let us all know when you have completed that research ?
So far I've single handed thru the Canal 3 times and have visited many (but certainly not yet all) of it's surviving WW2 facilities. Hot & humid "boots on the ground" and all that. Two research trips to the NARA archives at College Park, Maryland have turned up all sorts of interesting details but such informations are very difficult for my readers here to confirm so I seldom refer to them. URL's can be checked nearly instantly by any and all that can read my discussion board posted scenario on their screen so for their educational speed, that is what I try to use as sources. With acceptance that not all that one reads in print (whether in a book or on a compter monitor), is really true. Many of the more popular books such as Prange's "At Dawn We Slept" on the subject of PH are easily library accessible for many readers, if not already owned. Probably since it was never attacked, such detailed written works on the WW2 defenses of the Panama Canal seem to be more rare but I have found the (CDSG) Coast Defence Study Goup's in-house magazine to be an excellent source of good, hard to find WW2 Panama data. Still, not easy for non-members to confirm though.
P.S. According to the book I-400, - Written by ?
The Japanese apparently decided to dive bomb rather than torpedo the Gatun Gates in 1945 because training for accurate torpedo delivery would take too long. - Since you have refered to it more than once, what connections do you see between my 1941 flyingboats attack proposal and a 1945 submarine launched effort ? Four years of war later, with the wastage of Japanese pilots & skills that occured in the OTL, I don't see many resemblances at all. Wouldn't nerve gas bomb attacks on 3 American Atlantic coast cities have been more of an attention grabber for the Japanese at that late date ? A "no nucs for no nerve gas" stand-off might have been suggested ?? Unlikely, I know.
As a matter of interest, is there any record of a successful torpedo strike by a Mavis? - I can't say that I have ever tried to find one. This seems an odd question from a gent that only just asserted, "And remember – absence of evidence for a torpedo net is not evidence of the absence of a torpedo net. The same goes for AAA defences, etc", don't you think ? In your own words, little or no OTL evidence doesn't prove that a Mavis couldn't get the torpedo job done.
P.P.S. What is your purpose in soliciting information on this subject? Are you planning to publish or produce a wargaming scenario? - I can't claim to have devoted much thought to this aspect of ATLs. Glenn239 is known to be working on a wargame expansion version of his "Invasion of Oahu" AH though. If he is successful in that endeavour I would eventually add my ATL Panama scenario as a further expansion of his expansion but I have no board wargaming design or development experience to draw upon in that direction.
At this point in time I post to a subject because this is the way that I best enjoy history & learning. I find that a well researched and thought out challenge to my existing beliefs motivates me to really "dig into" any subject in a way that simply reading a book can never seem to do.