What IF: The Dec.7'41 Pearl Harbor Attacks Included a Blockship ?

Sorry, but I must disagree. My readings indicate that the IJN minisubs used at PH only contained enough air to be good for about 4 hours of submerged operation UNLESS the compressed air bottles inside were slowly opened. These however could NOT be refilled by the minisub itself and so were for "one time" use during an actual attack.

I think it lilkely that the OTL minisub following the USS Antares in the darkness had NOT accidentally breached at all but rather was running with her sail exposed and hatch open to replenish her internal air supply, just prior to entering the PH entrance channel fully submerged.

Granted, another minisub DID indeed broach when she fired not just one but rather BOTH of her bow carried torpedos in rapid succession while deep within PH so I think them only difficult to control when firing torpedos, NOT during regular navigation.

Sure there was. The three PBY inshore air patrol was a regular as clockwork 7 day a week air search flown counter-clockwise around Oahu from a Kaneohe NAS take-off at 0630 hours. By the time that my ATL blockship arrived off of Honolulu Harbor and the USS Ward was torpedoed by the IJN minisubs, that three plane patrol would already be 30-60 miles to the south of Honolulu checking the Pacific Fleet's usual exercise areas for any potential enemy submarines, before returning to Kaneohe NAS.

Visible everyday from Japan's Honoilulu Consulate where Yoshikawa was based.

Except that the 3 of them would already have left the Mamala Bay area, as they did everyday, about an hour before the Ward would be torpedoed and my ATL TatutA Maru would turn away from Honolulu Harbor in order to begin her intended scuttling run on the Pearl Harbor entrance channel.

 

What does blocking the ship channel accomplish for your "ATL" is it just to prevent US ships from exiting the Harbor?

 

My ATL Japanese would indeed be intending to keep those US Pacific Fleet warships locked up within Pearl Harbor.

With the added benefit of yet another massive demonstration of Japanese power being delivered straight to the American public. "With just ONE Japanese ship (and not even a warship at that), we can disable your ENTIRE Pacific Fleet ! Just IMAGINE what our BATTLESHIPS can do !" Be afraid, be very, very afraid.

My ATL Japanese couldn't know it ahead of time but the placement of such a blockship on THAT morning would have the benefit of almost certainly dooming the returning USS Enterprise taskforce. They were so low on fuel historically after returning from Wake Island that an entrance was made into a still burning Pearl Harbor on the late afternoon (1600) of Dec.8'41. Had my Tatuta Maru been scuttled in the entrance channel (with 5 IJN minisubs for company) I think that OTL refueling would have been aborted. Enterprise was of too deep a draft to enter Honolulu Harbor at the time so her nearest "gas station" was the old and slow US fleet oiler USS Neches, inbound with a load of bunker "C" ship's fuel but still some 1,200 miles east of Oahu.

Enterprise and her escorts would all be drifting in waters concealing 30 IJN I-boats, long before the Neches could arrive at her top speed of 9-11 knots.

As an interesting (I think anyway) side-note, the Neches at the time was TOWING an old American destroyer from San Francisco to Oahu. To be permanently moored inside Pearl Harbor and used in the teaching of damage control and fire-fighting techniques to new USN recruits. In the OTL it was scutttled before the Neches continued on westwards, totally alone. Fortunately for the OTL, she made it into PH without running across any of those 30 prowling I-boats.

Such a PH blockship would also have effectively hobbled the USS Lexington carrier group as well. Although not nearly so low on fuel as was the Enterprise TF, the "Lady Lex" and her flock of escorts would still be far from any friendly "gas station" available.

 

Who's quote is that?

You have 5 Midget subs, with 2 torpedos and two men each surving for 36 hours..........not going to happen in my opinion. The minsubs were just not that effective to begin with.

The other problem I see is with your intelligence gathering/ discemination ability you give the Japanese consulate. If they were tansmitting ship movements and locations to a covert attacking force I hardly think it would go unnoticed.

All radio transmissions, on both sides, would be interrupted as soon as your Bolckship began it's radio jamming operations. How would these continue once the ship was scuttled (bottom blown out) ?

I think you have added an overly elaborate plan that would have added little gain to the outcome of the attack.

 

My own imagining.

Where did "2 men each surving for 36 hours" come from ? It's not from any of my postings so, is your own imagination inventing things too ?

Which is one of the reasons that I have proposed what I think would be a much better mission for them, sinking the PH gateguard DD by surprise and helping to cork the PH entrance channel.

Historically the Japanese aviators were worried that the OTL submarine mission into PH itself might be discovered early and thus blow the whole air raid's surprise. My ATL mimisub mission DOESN'T send them up that channel until AFTER the Kido Butai's bombs/torpedos have started falling on Pearl Harbor so there is much less chance of an early warning being received by the US Pacific Fleet.

I believe you to be missing a key piece of the OTL Pearl Harbor puzzle.

Several authors have cofirmed that such was exactly what Yoshikawa historically did in the OTL. He sent daily PH ship movement reports via coded commercial telegragh messages from Honolulu to Tokyo. Those messages were then re-broadcast by Tokyo, out to Nagumo's Kido Butai strike force. His last telegram left Honolulu at 1801 on Dec.6'41 and was in Nagumo's hands by 0200 on Dec.7'41. Certainly not an instant report but still very timely. Try Prange's "At Dawn We Slept" to get up to speed.

I'd imagine that a gasoline or diesel powered generator could be installed as a part of the radio jamming suite but it really doesn't matter. The jamming is only intended to forstall a warning being sent out to the Pacific Fleet or to the American CAC defenses, by the USS Ward, right after she is torpedoed at about 0730. By that time it is probably too late for an Oahu wide alert to be acted apon by the American defenders, anyway. I imagine my ATL Tatuta Maru being scutttled at about 0745 -0750. Her jamming only needs to be even partially effective untill the KB's bombs and torpedos begin to fall on PH at 0755.

Being that the channel was only 40' deep and the Tatuta Maru was 84'+ from keel to main deck, that blockship's upper works aren't even going to get wet, anyway.

Sigh.

An unimaginative opinion voiced before you have considered what other benefits a blockship might give to the Kido Butai's flyers.



On an interesting (to me anyway) sideline point, I have just read that Captain Outerbridge, the just 2 days in command new skipper of the USS Ward when she sank that IJN minisub at Pearl Harbor, was destined to meet up with the Ward again several years later, at Okinawa. He was then in command of another USN destroyer ordered to rescue the survivors of a just kamikaze hit USS Ward, before sending her to the bottom with gun and torpedo fire.

How awful it must have been for him to have to sink his own faithful first command. Better in combat than under the breaker's torches, I guess ...

 

I can only point out that in the OTL, the Kido Butai sailed some 3,400 miles from Japan to Oahu, in complete secrecy, and attacked Pearl Harbor at 0755, just 5 minutes earlier than it's scheduled 0800 time.

Just 5 minutes early, over a re-fueling route of 3,400 stormy north Pacific winter miles. Nice work, wouldn't you agree ?

In addition, the mere presence of my ATL Washington approved Tatuta Maru (blockship) repatriation liner gives Nagumo a radio communication and timing co-ordination ability that he did NOT have in the OTL. If running late or early my TM could send a coded radio message to Tokyo (that would be picked up by Nagumo's skulking carrier group) without blowing the raid's secrecy.

For communication in the other direction, in the OTL Nagumo launched 2 cruiser floatpalne scouts early on the morning of Dec.7'41 in order to check for American warships anchored within Pearl Harbor and at Lahania Roads. Both of those floatplanes radioed in their plain language reports from over American territory, not from the KB's location to the north so as to NOT give away that strike group's position. Were the KB's strikes to be early or late, those 2 floatplanes could have radioed new instructions to my ATL blockship as it rounded Barber's Point, headed for the Port of Honolulu, and the USS Ward. Her speed could then be altered accordingly.

I don't feel that to be the case at all.

If you would re-read my initial scenario posting, you would note that I intend my blockship to begin it's rush of the Pearl harbor entrance channel starting at about 0730, when the USS Ward is torpedoed by an IJN minisub. Some 3 miles from the PH entrance nets and with NO clear direct line of sight between the net location and the USS Ward's "patrol box". Some 30 minutes BEFORE the first scheduled drop of Japanese bombs and torpedos on PH. Not AFTER the KB's air attacks had begun at 0755.

Considering the distance from those nets to Pearl Harbor and that there were no OTL initial air attacks in the area of those nets, how would the net tender's crewmen know that the warplanes were Japanese ? Binoculars from that distance, and half an hour before the air raiders got there, aren't going to help those Americans much, are they ?

Also, I'd expect the net tender's crewmen to follow their orders, not to just "wing it" and do whatever the hell they felt like doing. Until those orders were officially changed by their chain of command. Historically that was NOT done until 0840.

How were they to know that what they were seeing, even after 0800, wasn't just some elaborate drill or training exercise, as many of the OTL witnesses first believed of the KB's warplane attacks ?

Also, you probably don't realize that the twin nets blocking the PH entrance channel (during the hours of darkness only) were NOT high strength anti-submarine nets at all but mere merely 1918 vintage steel anti-torpedo netting that formerly hung off the sides of US battleships. After 1941- 1918 = 23 years in salt water, how much strength do you think that they would really have in stopping a charging 17,000 ton cargo-liner doing 20+ knots ? One with concealed 6' deck guns that would be trying to sink that net tender before it could close the gap.

They were in fact only intended by the American defenders to catch torpedos that might be fired straight up the entrance channel by a submarine attempting to bag a USN warship entering or leaving on a dead straight course some 3,450 yards long.

 

I am curious here, I admit I haven't read the entire thread so if this was covered I apologize. What was the proposed route of the Tatsuta Maru? Would it have crossed the path of Halsey’s task force as it made its way toward Wake after November 28th? I ask this because I wonder if Halsey’s understanding of his departure order wouldn’t put the "block ship" in jeopardy if Halsely’s task force encountered it going toward Hawaii. He was flying patrol craft well outside of his task-force’s path to make sure he himself wasn’t "ambushed" by any Japanese forces.

"Admiral Halsey said that when he left to go to Wake Island, he asked Admiral Kimmel how far Admiral Kimmel wanted him to go and Admiral Kimmel said, "Use your common sense." (p. 298)

"Admiral Smith said that before Admiral Halsey left in the ENTERPRISE to deliver Marine fighters to Wake, he asked Admiral Kimmel what he should do in case he met Japanese forces. Admiral Kimmel said that in that case he was to use his own discretion. And, Admiral Halsey replied, that those were the best orders he had received, to keep his movements secret and that if he found even a Japanese sampan he would sink it. (p. 43)

goto:

XIX. REINFORCEMENT OF MIDWAY AND WAKE

Also it was sometime earlier that FDR had made the "shoot on sight" order applicable in the Atlantic in relation to German U-Boats (wasn't it), perhaps that coupled with Kimmel's "use your common sense" remark lead Halsey to that conclusion as both men knew of the deteriorating relations between the US and Japan. I wonder if even a passenger ship flying the Japanese ensign would have been immune to continue on a path toward Hawaii.

As I say, just curious as to how that alteration might have changed things as well. Would Halsey have "sunk it", or only boarded it and turned it back, or simply detached an escort for the passenger ship? America was already denying Japanese ships access to and transit through the Panama Canal, under the pretense that we were "overhauling" the canal. The Japanese protested that only their ships were denied passage from west to east, and European Axis ships denied access east to west. I wonder if Halsey would have allowed the TM free, unescorted passage.

 

brndirt1:

A two part answer:

In the OTL, neither the Tatuta Maru nor the Kido Butai were spotted by anybody.

In my ATL, the Tatuta Maru (blockship) would be leading the Kido Butai across the northern Pacific by about 60 or so miles to act as yet another tripwire scouting vessel for that task force. And so wouldn't have been spotted by anybody either.

As to your question about Halsey being a crazed and bloodthirsty warmonger, I don't think that even he would be nuts enough to ignore Washington's official approval of a 4th repatriation liner's scheduled trip between Yokahama/Honolulu/Balboa/San Francisco carrying home AMERICAN civilians from Japan.

FDR had made it perfectly CLEAR that he wanted NO "causus belli" affronts presented to the Japanese Empire as war approached. No easy excuses for them to declare to the world that 'America had started it' were to be provided. A deliberate peacetime attack on a (theoretically) un-armed Washington approved Japanese cargo-liner, still in international waters, carrying American civilians home from Japan, would be well BEYOND the bounds of civilized behaviour expected from any United States Navy officer.

Such would be grounds for hundreds of 1st degree peacetime murder charges and even if ordered by Halsey, I'd hope his junior officers to be bright enough to have immediately removed him from command on medical/mental grounds BEFORE aircraft were launched or warships detached.

 

Well, I didn't actually suggest Halsey would "sink" the ship if he encounted it as his only option. He could have boarded it, or escorted it without endangering the ship or its passengers and crew, could he not?

And I didn't mean to imply that Halsey was a "crazed and bloodthirsty warmonger", only that he was, at that moment in time very intolerant of the Japanese. I don't see him allowing a Japanese vessel to proceed toward Hawaii without warning both the ship and Pearl Harbor of its existence and sailing direction. But, that was only being said as I didn't realize the route proposed by your two ships. If they were far enough north they may have gone undetected, but I still fail to see them making a "blocking" move in the channel leading out of Pearl.

The harbor wasn't allowing civilian ships in for months before Dec. 1941. A non-military ship, flying a foreign flag would arouse more than a bit of suspicion.

 

This is of course, another perfect case scenerio and you are again forgetting to invite Mr Murphy to your little party. Remember, in the OTL, the Japanese were counting on the US Aircraft Carriers to be in PH that morning, but Murphy dictated otherwise, spoiling a major part of their attack plan. Therefore, in your atl, I would imagine that the YTs' near the harbor entrance, not to mention the USS Antares, Condor and Destroyer Helm would pursue one of two courses of action after seeing the USS Ward blow up from torpedo hits. They could treat the Japanese maru as an enemy combatant, taking her under fire and ramming her, to keep it from blocking the ship channel, or they could simply push the Liner out of the shipping channel and onto the reef before it settled, just like what was done with the USS Nevada. This would keep the ship channel open for the ingress and egress of the Pacific Fleet.

Your midget submarines did not have the best navigation equipment either and three of the five subs got lost, broke down or sank, while taking no active role in the OTL. What makes you think that the same would not hold true for your ATL?

 

Not legally.

Do you not realize that the un-invited boarding of a vessel of another nation, in internatioanl waters, under threat of violence, is an Act of War ? Piracy at the least.

In light of FDR's instructions to the US Navy, an immediate career ending move for Halsey, if not a reason for much stockade time.

You're just not "getting it" are you ? The Tatuta Maru was already EXPECTED in Honolulu and had already been GRANTED Washington's pre-approval to carry AMERICAN CITIZENS back to the United States from Japan. She was sailing on a two nation APPROVED repatriation voyage intended by both nations to somewhat reduce rising international tensions at the time. But for drastically different OTL reasons.

Pearl Harbor was a USN fleet base and had not allowed civilian shipping in ever since it was declared such, several decades previously.

If you were to take a few moments to open the maps that I have previously souced within this thread's postings, you would immediately note that the entrances to BOTH Pearl harbor and Honolulu Harbor are but 6 short miles apart. As my ATL Tatuta Maru approached the Honolulu Harbor entrance from the southwest, she could not help passing only some 3 miles from the entrance to Pearl Harbor.

As an officially Washington approved repatriation liner (the 4th passing thru Honolulu in the last two months) SHE WOULD BE EXPECTED TO BE NOWHERE ELSE BUT RIGHT THERE.

She might have triggered boredom, but not suspicion.

Until the nearby USS Ward blew up. that is.

Even then, the historical reactions on Oahu during the OTL Dec.7'41 Japanese attacks suggest that at least a few minutes of confusion could be expected while steps were taken to determine if the Ward's disaster were accidental or deliberate.

My ATL Tatuta Maru blockship would use those minutes of confusion to begin her run on the Pearl Harbor entrance channel, locared some 3 miles away. At 20 knots, a distnce she could cover in only 9 minutes.

 

I got that impresion from your post here:

I read that as saying there are still 5 Japanese Mini subs waiting at the entrance at 1600 08 Dec.

And I suppose that the sinking of a US Naval vessel is going to raise no suspicions?

Here is an assesment of the IJN Mini Subs at Pearl Harbor it seems only one of them was able to launch it's torpedos.

( Problems with the Mini-Submarine at Pearl Harbor Theory )

If during the Historical Time line the Ward was able to sink the mini sub then what makes you think it would be able to do so in your "ATL" ?

That's 8 full hours when dealing with ships at sea 8 hours is huge

Really? is that how you want to do this?

 

How do you intend to keep the sound of the torpedoes blowing up the Ward from reaching American ears, not to mention the flash of the explosion and concussion wave? The PBY's will see that even if they are ten miles away. Remember, there are two US Army forts at the mouth of PH and they could easily see what was going on, even three miles away.

IF you take those US YT's and other ships around the harbor mouth under fire, the forts will break out their ready service 3" ammunition and take the Maru under return fire. You are forgetting that most US ships in PH opened fire on the Japanese aircraft within seconds of the first attack and without any orders from their officers, while using ammunition that was on hand, because it was SOP that half of a ship's AAA suite had to be manned 24/7 while in Pearl Harbor. There would be no need of a change of orders.

 

dabrob. Why is your information infallible while the information provided by others ignored?

You see, there is a reason why alternate history authors are viewed with such cynicism. The habitual loss of information which might deny the hoped for change.

Why cant we be more interested in what ACTUALLY happened instead of living in what MIGHT of happened?

 

Mr. Murphy is exactly the reason that I order ALL 5 IJN minisubs to track the USS Ward. How much more "insurance" overkill would you like ? Should I include also the additional 5 full sized I-boat mothersubs that still cruised Mamala Bay in the OTL too ?

This is where you diverge from the OTL. If you check, you'll find that none of those USN warships was anywhere near being in a position to see the events transpiring at the USS Ward's location at 0730. All were well within the PH entrance channel or had already reached Pearl Harbor itself.

Might I point out to you that the USS Nevada had NOT dropped either it's original compliment of anchors nor two extra ones that my original ATL scenario posting added to the Tatuta Maru as she was being modified into a blockship. Neither did the USS Nevada have her bottoms blown out by carefully considered and placed demolition charges designed to send her quickly down the only 12' between her bottoms and that channel base coral.

If you were to conduct a bit of research you would find that the guns carried by the Antares and the two minesweeepers (Condor and Crossbill ?) were but tiny popguns when compared to a 17,000 ton cargo-liner fitted with some 6" guns of her own. Neither were any of the minesweeers actually tugboats fitted with engines powerfull enough to push a resisting 17,000 ton opponent anywhere.

The USS Helm exited the PH entrance channel at 0817 in the OTL which indeed put her at the Tatuta Maru's best blockpoint at about 15 inutes after the Tatuta Maru would already have have been scuttled. Would her momentum be enough to overcome the inertia of an achoried and scuttled 17,000 ton block ship is the question. I don't think so and by ramming, the Helm risks adding her own shattered hull to the blockship pile within that channel. i don't think that her captain would even attempt to do so as the TM's 6' guns would be knocking big hoes in her too.

My ATL Tatuta Maru would only be at any risk of being knocked out of her proper blocking position if a US battleship should ram her on it's way out of the harbor, before she was properly settled the 12' down. Not a likely event on a peacetime Sunday morning according to Japan's Honolulu Consulate ship movement reports to Tokyo. Even if such were to happen, the combination of Kido Butai warplane inflicted damages and IJN minisub torpedos might succeed in sinking the battleship in the entrance channel anyway.

AFAIK only 1 minisub had a faulty gyro-compass and although the crew tried hard, didn't get into Pearl Harbor because of it.

All 5 of my ATL minisubs would not have to thread the PH entrance channel IN THE DARK for one thing. They would be tracking the American gateguard DD on it's well known regular "patrol box", in daylight. Much easier.

 

I do try to respond to every posting made here and to rebutt all points to which I have conflicting information with that posted by others. I usually post sources, page numbers and short quotes. They don't so I tend to take my hard information over their "recollections". 'Tis as simple as that.

I wasn't aware that I had done so here. Please site a concrete example. Consider also that I am but one time-limited man (with a career and family) trying to keep up with posting answers to about 8 opponents now.

Mostly because I feel that I have already thoroughly researched what happened in the OTL on Oahu. Only but composing an ATL can I test my knowledge and my own interpretive skills. Only by posting an ATL scenario can I submit my knowlegde and the conclusions that I have drawn to (hopefully) knowledgeable peer review. 'Tis much like the masters and Phd approach taken by modern universities. Only by exploring new ground can you prove your sure knowledge of the existing history.

If you really feel that way then why do you read/post in the "What IF" section of this discussion board ? You will surely only further upset yourself if you continue to do so.

 

Sorry for leaving out a step here. In my rush to answer everyone posting, I sometimes go too fast.

I would expect the US light cruiser St.Louis to exit Pearl harbor quickly in my ATL, just as she did in the OLT. That 10,000 ton bulk trying to slowly squeeze past my scuttled Tatuta Maru at about 0950 would be too tempting a target for the 5 lurking IJN minisubs to ignore. The sinking of that 2nd blockship would reveal the presence of the 5 minisubs and would eventually lead to their shallow water pounding by Americcn PBY dropped depth charges. Any minisub that survived would have to slip out to sea on the night of Dec.7-8'41.

So no, I wouldn't expect minisubs to be lurking there 36 hours later. More probably 9-10 hours, till dark, wolud be the maximum outer limit.

Of course it would. The question is, just how long would those suspicions take to be turned into real and effecive American counter-actions ? The OTL suggests that such would have taken quite awhile.

At least two minisubs as I recall. One unloaded two torpedos within Pearl Harbor and missed with both while another almost tagged the light cruiser St. Louis as it exited the channel at 25 knots.

I don't think that the USS Ward will be able to sink a minisub in my ATL scenario, at all. In fact I think that she will easily fall prey to my 5 ATL minisub assasins, instead.

Then it is fortunate for me that we deal with ships at anchor in port in this scenario rather than with ships at sea

Do what ? Please explain.

 

So now the mini subs are tasked with finding and destroying the Ward. I thought they were going to aid the Tatuta Maru in Blocking the Harbor exit?

The Mini Subs were not effective in the Historical Time Line at sinking boats tied to a pier and now you are going to assume they will be more successful against a ship at sea?

As soon as the Ward is engaged they will either send a radio message, signal light, semi phore message or be observed by one of the PBYs. Even a lazy pilot on a sunday morning is surely going to investigate a plume of smoke.

Doesn't sound too successful to me in either case they would not have been capable of firing the opening shots of the conflict unless all 5 fired their torpedos at the Ward. 40% of the torpedos were fired with a zero success rate.

Well the Ward and the Condor were not at anchor or moored to a pier

You need to show the same courtesy you have been shown, do not malign those with differing opinions.




Again you have over estimated the capabilities of the IJN and underestimated the resolve of the US Navy.

The goal of the Japanese, at Pearl Harbor, was to destroy the Carriers and inflict as much damage as posible to the US Fleet. Given those criteria the Japanese attack was only 50% successful.

If Japan had all of the intelligence resources and capabilities why didn't they wait to launch the attack when the carriers returned?

You propose an "ATL" that depends too much on everything going as planned and rest the success of it on the least successful attribute the Japanese had; the midget subs. You put 5 of anything in close proximity to one another , such as attacking the same target, without communication and they will either collide or be spotted.

You have posted an unplausible situation.

 

I don't.

In the OTL, the Ward fired it's guns and dropped numerous depth charges on that minisub, in the same area. No one on shore noticed nor cared. Even the Ward's TWO OTL radio messages failed to stir the USN or CAC into life before the Kido Butai's warplanes struck..

They will be 30-60 miles away to the south checking out the US fleet's regular exercise areas, not just 10 miles away.

I've covered this before in other of my postings but it seems that you don't read.

If they were manned and ready, watching for seaborne attacks rather than following General Short's orders to be wary of sabotage attacks only as in the OTL.

They weren't.

Even if alert, it still would take much time on a peacetime Sunday morniing to roust the guncrews and ready the guns and ammunition to firing status.

I've covered all of this in an earlier posting already.

So ?

What is some badly fused AA fire going to really do to a 17,000 blockship that her crew WANTS to sink in mid-channel nearby ?

I've not forgetting anything.

'Tis you that has forgotten to check and see that the buildings of Hospital Point, the remaining coal piles of the PH coaling dock and the western fuel storage tankfarm will block the line of sight/fire that you seek to use against my blockship THAT WANTS TO SINK.

You just can't seem to grasp that in this ATL scenario, the surprised and sleepy peacetime American defenders have only 9-12 minutes after the Ward is first torpedoed to knock the Tatuta Maru off of her course. Once she enters to PH entrance channel, it is essentilally too late to stop her mission.