What if...the Japanese had landed troops in Hawai'i immediately after bombing Pearl?

This BS doesn't hold up to any close scrutiny. The Japanese seldom made landings against defended beaches, and when they did they invariably got into trouble. The initial Malaya landings were against a beach defended by a half-trained Indian brigade armed with rifles and a few machine guns, yet they came within a hair of being repulsed. They succeeded only when the British commanders lost their nerve and ordered a retreat. The landings against the beaches on the Bataan peninsula were all annihilated to the last man, The landings against Corregidor were badly botched and proved extremely costly, they succeeded only because the defenders were badly demoralized by their situation. The initial landings on Wake were repulsed with heavy losses.

The Japanese may have been good at making assault landings against Chinese peasant conscripts, but when they had to face defenses like those on Oahu, they were in deep trouble. In the first six months of the war, with few exceptions, the Japanese were successful largely because they were, in effect, expanding into a military vacume.

Yeah? Well, how do you explain the fact that every time the Japanese came up against the US Marines on anything like an equal basis in 1942, they lost?

What the Japanese had going for them was years of intelligence that told them where to attack so that they wouldn't meet heavy opposition. When they had to improvise after their "First Phase" operations ended, they were pathetic.

 

formerjughead, you replied with,

I'll give you one thing; you are certainly well thought.

Many thanks for the kind word. I do try but certainly don't always get it right.

The one thing you are missing is that Japan attacked Pearl Harbor to sink the Aircraft carriers. The American Carriers are key to Japan holding any real estate in the Pacific.

I agree completely but the presence of the American Pacific Fleet carriers at Pearl Harbor is something that not even Yamamoto could control.

I have tried to write an ATL Japanese invasion operation scenario as much as is possible, in the Japanese "style" of the day, including all of the absurd complexities and reliance on the Bushido spirit that the 1941 Japanese military was so fond of. 'Tis often not the most sensible military plannning that might have been used instead but then my ATL scenario would be an American one, not a Japanese one, wouldn't it ?

The presence of the radio capable Tatuta Maru with my ATL Japanese invasion taskforce MIGHT give Yamamoto the ability to delay the Oahu strike by one day, so as to still gain some advantage from Oahu's too deep weekend relaxation BUT that does not seem possible in the case of the near simultaneous Kota Bharu etc. landing in Malaya and Thailand.

As soon as the Japanese even looked like they would try to occupy Hawaii, for even a short period, every US Naval resource would have been allocated to the defense of the Islands.

Also quite true which is exactly why both the OTL Japanese air attack plans and my own ATL invasin plans demand complete pre-war secrecy.

Sadly for the Dec.7'41 Americans, there wasn't much else of US military significance anywhere near the Hawaiian Islands that could have rushed in to help. Had the 2 widely seperated USN carriers attacked the KB at 1:6 odds each, both would have been quickly sent to Davey Jones's Locker.

The likelyhood of US reinforcement from the West Coast is yet another reason for my ATL Japanese invaders to get ashore on Oahu fast, rather than taking other of the Hawaiian Islands and building airfields there with which to soften up Oahu for later invasion. I feel that it needed to be done quickly, or not at all.

I have typed many times that a USN Atlantic Fleet counter-attack would be expected round about the end of January 1942.

You propose that Japan occupies Hawaii for a short time ans uses it as a bargaining chip..........wouldn't happen.

Any other ATL Japanese strategy that I can think of would eventually be suicidal. But pehaps you refer instead to the low likelyhood of the even more wounded American nation ever agreeing to "play ball" ?

Guam, Midway and Luzon would not wither on the vine they would be supplied through the Phillipines, Singapore and Australia. Japan could not hold Singapore without controlling the Phillipines.

If you would re-read my posts you will be reminded that I will more quickly invade Mindanao and by establishing Japanese LBA bomber and fighter units there in co-operation with the OTL LBA units on Formosa, establish an air blockade of the Philippines as the OTL Japanese operations continue southward.

All else "withers on the vine" since, as you yourself have just stated above, EVERYTHING American available anywhere will be sent instead to the relief of a Hawaii under invasion. Not to the Philippines nor Guam nor Wake etc.

You can't have it both ways, afterall.

 

While I had this massive response, it seems the system has eaten it. I will add that the following tidbits:

The IJN did not practice using floatplanes from their ships for gunnery spotting either against shore targets or at sea. These were intended for scouting. So, the battleships are firing off a map as they did at Guadalcanal. Gunfire support of naval landings was not something the IJN made a habit of practicing. So, the likehood is that their efforts in this area would be like they were elsewhere:
They would fire far too few shells to be effective.
They would largely leave the target(s) undestroyed.
They would grossly exaggerate the effect they had.
The result would be the landing troops would be hosed by the defenses.

As for the coast defenses:

You forgot the two 14" guns at Fort DeRussy, along with the 20 fixed and 12 rail mobile 12" mortars that were specifically sighted for repulsing landings. These in the Philippines proved devastating against the Japanese.
The coast defenses also have nearly 100 155mm guns and 32 240mm howitzers that can be moved to one of over 100 "Panama Mounts" around the island. The 16" batteries elevate to 50 degrees and fire to 49,000 yards. They have a 360 degree field of fire their magazines are invulnerable to return fire and anything short of a miracle direct hit on the gun is useless.
The terrain is far more a henderance to the Japanese in this scenario than the US who sited their batteries to be able to blanket the island and surrounding waters with fire. A landing anywhere on Ohau is subject to 12" mortar fire in varying amounts. This alone would be a major problem for a landing force.
There were also 8" guns and 12" mortars on railcars that could move anywhere on the island's rail system. This too would prove a problem as it gives even more mobile artillery to the US to smash an invasion.
There are also bunkers and pillboxes around the island built in the mid 30's an onward.
The US coast defense fire control system like the US Army artillery system allows any battery to be controlled from any station. There are stations on most of the major mountian tops under massive amounts of earth and concrete. These will call down ungodly amounts of fire on the landing Japanese troops. Just the mortars alone would severely disrupt any landing attempt.
I would like to see the Japanese firing off a map take out a 12" mortar battery like Battery Burkhammer on Diamond Head that is built into the side of the volcanic crater and completely masked from fire from seaward. This battery if in range (17,000 yards)would have devastated a landing with shell fire.

 

Devilsadvocate, you waded in with,

There are just a couple of problems with your suppositions.

Only a couple ? I'm getting off lightly then.

First, the Japanese didn't have anywhere near a million tons of spare shipping just sitting around waiting for something to happen, regardless of your claim to the contrary.

1,687,000 tons actually as per the breakdown that folllows below:

Postponed invasions:

Luzon: 111 transports for 619,161 tons
Guam: 8 transports for 36,969 tons
Wake: 2 transports for 17,934 tons
Gilberts: 4 transports for 31,029 tons

Total freed shipping: 125 ships for 705,093 tons.

Added to this total is the cancellation of Japan's Armed Merchant Cruiser Program, plus the employment of the following stranded German merchantmen

Scharnhorst of (18,184 tons).
Teizui Maru 8,428 brt (taken over by Japanese on Nov. 2nd 1942)
Havenstein (7,973 tons) sold to Japan 1942 as Teisho Maru
Quito (1.230 tons) sold later to Japan as Teifuku Maru
RC Rickmers (5,198 tons) sold later as Teishu Maru
Winnetou (5,113 tons) sold later as Teikon Maru


Total additional tonnage:

72,414 (cancelled auxiliary cruiser program)
46,126 (purchases of stranded German vessels)
Total: 118,540 tons

A few more ships are available from naval programs, if necessary:

Hospital ships (4) - for 33,491 tons
Submarine tenders: Rio de Janeiro of 9,627 tons and Nagoya of 6,071 tons were being employed as sub tenders at bases the Home Islands. Being in home ports, other arrangements could have been made at these locations without impairing combat efficiency.

After this, the last major source of transports for Hawaii was either China or the civilian pool of 2.66 million tons. But China had already been thinned out, and tapping the civilian fleet would have repercussions on the Japanese economy,

"The Cabinet Planning Board calculated before the war that the civilian economy required 3 million tons of merchant shipping to continue to functioning. Coal, transportation would occupy 1.8 million tons, while the movement of agricultural products and supplies (450,000 tons) and steelmaking materials (300,000 tons) would absorb most of the rest. Any drop below the 3 million ton minimum would threaten serious disruption of the economy. Government studies predicted that if Japanese industry could call on only 2.5 million tons, the availability of resources considered to be of secondary importance (coal, salt, fertilizers, soybeans, bricks, cotton and various ores) would fall by one-fifth, and many other items would become even scarcer. A further loss to 1,500,000 tons would mean a 20 percent curtailment of steel and rice production, a 60-percent drop in the second(ary) items, and a virtual cessation of most other imports."

The Japanese Merchant Fleet in World War II, 34-35

"Later studies predicted that the planned requisitioning (2.5 million tons) would mean a one-quarter drop in steel production and about a 15-percent fall-for other products. A month before Pearl Harbor, the Cabinet Planning Board confirmed these figures, but the board believed employment of sailing ships with auxiliary engines, greater utilization of iron foundries serviced by railroads, consumption of stockpiles, and collection of more scrap iron could compensate for lost shipping."

Ibid, pp76


In the event, the total military mobilization exceeded the 2.5 million tons envisioned by a considerable margin and the 2.66 million tons remaining under civilian control was short of the 3 million tons Japanese planners thought necessary to maintain the economy at an acceptable standard. In fact, of the 2.66 million tons left to civil sector, a full 1/3rd - 840,000 tons - were passenger vessels "ill-suited" for cargo transportation and therefore of little to no use in supplying raw materials. Studies suggest that the actual tonnage of useful vessels in the civilian pool was less these passenger ships - the real pool was about 1.6 million tons (as per USSBS, Vol 9). The rest (840,000 tons) were of next to no utility (Japanese Merchant Fleet, pp75).

These passenger ships are therefore available to the military as troop transports, useful for a Hawaii invasion.

Summary:

Grand total of shipping freed up from cancelled invasions: 705,093
Plus cancellation of aux. cruiser program: 72,414
Plus purchase of German ships: 46,126
Total: 823,633 tons
Plus 2 sub tenders and only 1 (of 4) hospital ship: about 24,000 tons.
Totals 847,633 tons

Plus civilian pool passenger ships of little use to economy available as troopships: 840,000 tons.

Total potential shipping available for my ATL Hawaii offensive: 847,000 tons + an additional 840,000 tons of passenger liners = 1,687,000 tons

Second an invasion of the Oahu would require the support of the major part of the Japanese Navy, which also was tasked with covering the Malaya operation, the Philippines operation and various other minor points such as Guam and Wake.. Yeah, I know, you plan on ignoring the Philippines, Guam, etc. but exactly what does that buy you in terms of spare naval units?


Summary of Dec.7'41 OTL vs. ATL allocation of major IJN units.

Carriers
Type.......Location..........Historical.........ATL
CV..........Hawaii..................6................6
CVL........Johnston...............0................1
CVL........Oahu (CF-CAP).......0................1
CVL........Mindanao..............1.................1
CVL........Japan...................2.................0
Total.................................9.................9

Seaplane Tender...............Hist...............ATL
Japan................................1..................1
Malaya..............................4..................3
Philippines..........................3..................3
Guam................................1..................0
Gilberts..............................1..................0
French Frigate Shoals...........0..................2
Johnston............................0..................1
Total................................10................10

Battleships

Area.................................Hist................ATL
Japan.................................7....................0
Malaya...............................2....................2
Hawaii................................2....................9
Total.................................11..................11

(includes Yamato serving in a limited combat capacity at Oahu, OTL commissioned Dec 15th, 1941),

I assume that her construction had been accelerated early in 1941 when the imminence of war in the Pacific became apparent....the accelerated construction resulted in no problems or operational difficulties. Her trials in October 1941 were a great success, and a speed of 27.4 knots was realized....
Battleships, Garzke, pp54)

Heavy Cruisers.

Area...................................Hist...............ATL
Malaya.................................7...................7
Hawaii..................................2...................5
Marshalls...............................0...................1
Johnston...............................0...................1
French Frigate Shoals..............0...................1
Philippines.............................5....................3
Guam...................................4....................0
Total...................................18..................18

Light Cruisers.

Area..................................Hist..................ATL
China...................................1.....................1
Hawaii..................................1.....................5
Johnston...............................0....................1
French Frigate Shoals..............0....................1
Japan...................................4....................3
Marshalls...............................1....................1
Malaya..................................4....................4
Philippines..............................5....................3
Wake....................................3....................0
Total...................................19...................19

Destroyers.

Area.............Hist.....................ATL
China.............3.........................3
Guam.............4.........................0
Hawaii............9........................27
Japan...........25........................13
Midway..........2..........................0
Philippines.....30........................20
Air Rescue......3..........................0
Malaya.........24.........................24
Borneo...........5..........................5
Marshall.........8...........................2
Johnston........0.........................10
FFS...............0..........................3
48th/16th.......0..........................6
Total............113.....................113

But the major problems don't really start with logistics although that issue was patently impossible for the Japanese to overcome;

I don't agree, as I believe that my data above clearly shows.

the real problems are the defenses of Oahu. You've said that the only way a Japanese invasion of Hawaii can succeed is if the invasion force achieves complete tactical surprise; therein lies the insurmountable problem.

Maybe but I have done my homework and I don't think so.

It is axiomatic in warfare that, when attacking a single objective, tactical surprise can only be achieved once.

Then it had better be a good one, hadn't it ?

Yet, in order to successfully invade Oahu, the Japanese had to do three things there, all of which were dependent on tactical surprise for their success and two of the three could not be done simultaneously.

In your opinion.

1. They had to destroy completely the American naval force at Pearl Harbor and in the surrounding waters. If they weren't able to do that, any attempt at a landing is purely academic.

One of the reasons that I have sent 8 (and possibly 9 if posters here can agree on an early Yamato appearance) of the Combined Fleet's 10 battleships along to help out the Kido Butai. You haven't forgotten about the 28 (+5 minisubs) OTL Japanese submarines surrounding Oahu have you ?

2. They had to destroy the American air power based on Oahu. It is a proven axiom that without air supremacy, no assault landing can prevail.

Considering that my CF battleships will add to the destruction wrought by 3 waves (not just the OTL 2 waves) of the Kido Butai's warplanes, I don't think this too difficult. IJA landing troops will also be assaulting the coastal Bellows Field and Kaneohe NAS just after dawn also , thus freeing up additional KB flights for other strike missions against American air power on Oahu.

3. They had to effect an assault landing against ground defenses as formidable as anywhere in the world.

Except that at dawn on the OTL morning of Dec.7'41, the US Army's two Divisions on Oahu, save for a few anti-sabotage sentries ordered out by General Short, were still tucked into their Schofield Barracks and Fort Shafter beds, well within the totally unexpected reach of ATL bombarding IJN battleship guns.

None at all were even deployed, let alone dug-in, at their assigned invasion beaches. Historically the first US Army battalion left Schofield Barracks for it's assigned beach at 0930 when the OTL Japanese air attacks had begun at 0755. Nearly 1.5 hours later while NOT under IJN battleship bombardment as they would be under in my ATL scenario

The real problem is that all three of these conditions can only be brought about by the Japanese through attacks enjoying tactical surprise, but while the first two conditions might be achieved with one series of air attacks during daylight hours, as historically almost happened at Pearl Harbor, an assault landing cannot succeed at tactical surprise unless it is launched during hours of darkness.

Which is why my ATL Japanese will first land at night. Seems obvious.

You can't have tactical surprise by both the landing forces and the carrier air forces; one or the other has to come first, which will deny the necessary condition to subsequent attacks.

I don't see the situation in that way at all.

Prange's book "ADWS" details that Genda had originally scheduled his air attacks for take-off in total darkness with a just after dawn arrival over Pearl Harbor to allow daylight attacks on the USN's warships found there.

This was delayed to a sunrise take-off time when it was realized that not all of the 5th Carrier Division's (the new Shokaku and Zuikaku) pilots were night flight certified. They had been trained in night operations but rigid KB training schedules for the OTL air strikes had prevented their actual certification testing. By the simple choise of reshuffling the warplanes of the 1st and 2nd waves, this delay could have been avoided and more daylight hours thus provided to allow a 3rd wave later in the day on Dec.7'41.

Yes, such a earlier air attack might have been detected earlier by the Opana Point US radar but since the OTL Japanese didn't know of it's capabilities, I cannot now allow my ATL Japanese to attempt to circumvent it.

I can only point out that in the OTL, that radar did pick up the inbound Japanese air strike and nothing effective was done to warn PH or the rest of Oahu. I also point out that the two Japanese cruiser scout planes dispatched by Nagumo were both picked up by 3 seperate American radars and once again, nothing was done to warn either PH or the rest of Oahu.

Even if an air attack warning were issued, kost American fighters on Oahu were parked wingtip-to-wingtip without fuel nor ammunition. None would have been able to get off of the ground before the 1st ATL Japanese airstrike wave arrived.

Thus in my ATL, the 1st wave of KB warplanes will be attacking Pearl Harbor at about 0615 rather than at the 0755 time of the OTL.

with the proper co-ordination, all three ATL Japanese attack types will thus be able to "arrive" at around 0615.
The IJN battleships off Oahu's eastern shore will open fire at 0615,
The 1st KB wave will begin to bomb at 0615.
The IJA and JSNLF troops that snuck ashore in the darkness will emerge from cover and begin to overrun their assigned targets, also at 0615.

Only a very few Japanese attacks will begin before 0615, most notably an 0600 covert attempt on the Mutual Telephone Company's downtown Honolulu switchboard office.

In any case, assault landings rarely are able to achieve tactical surprise; a seaborne invasion force is just too difficult to conceal on approach and requires too much time to prepare the landing force once it is positioned off the target beaches.

With the initial landing wave of IJA light infantry troops already loaded into their lifeboat davit mounted landing barges, I don't think so.

For example, The Japanese carrier force attacking Pearl Harbor remained undetected at 200 miles distance from Pearl Harbor, largely because it could run into it's launch position at 25 knots or better from over 500 miles out. An invasion convoy proceeding at a maximum of around 10 knots does not have any such luxury.

It appears to me like you haven't yet read that my 1LW will consist of only 3 cargo-liners and just 6 JSNLF "patrol boats" already converted with diahautsu landing barges and stern ramps from which to quickly launch them into the sea. All capable of 20+ knots, not just 10.

In order to be able to launch it's attack it has to be within 4-5 miles of the beach and has to be there, not a few minutes before it launches the attack, but at least two to three hours beforehand. That means it has to start it's run in from under 100 miles. In an area with as much routine air and sea traffic as Pearl Harbor the odds of being spotted at that distance are overwhelming.

Perhaps we can have a more fruitfull discussion AFTER you have read my previous invasion postings here for the first time ?

I can guarantee that neither the IJA, nor any other Army with any amphibious experience is going to allow their slow and vulnerable transports, packed to the gills with troops and valuable equipment, to steam within 100 miles of enemy air bases as existed on Oahu, nor for that matter an intact enemy naval base. They are going to insist that those bases be destroyed, or at least neutralized, by air or naval attack long before their precious transports come anywhere near the target. Of course, if that happens, there goes your tactical surprise.

Desperate times call for desperate measures.

Again, I might find your criticisms more valid if you had actually read any of my previous postings here. You are not even remotely discussing the ATL Japanese landing plans that I have presented.

Creating the absolute minimum conditions for a successful assault landing precludes the one other minimum condition for the success of that landing; tactical surprise.

I have been quite clear that my ATL Japanese will NOT be making any assault landings at all, if, by the term "assault landings" you refer to landings on defended Oahu beaches. My vision of the initial night time landings on Oahu's shores is one of barge loads of Japanese quietly coming ashore on deserted peacetime beaches often backed by the electric lighting of the still sleeping Hawaiians.

Since Genaral Short had issued ONLY anti-sabotage alert watch orders for important installations on Oahu, there were NO extensive beach patrols nor oceanfront sentries watching for landing barges out on the dark ocean, on that last peacetime liberty Saturday night. The only "beach patrol" on that Saturday night was a once every 4 hours truck mounted drive around Oahu's coastal highway. At night, the truck headlights could be seen approaching from miles away thus giving my Japanese landing troops ample time to hide from American sight.

Even the CAC observers who were usually posted to the 100+ ridgeline observation bunkers on Oahu had been given their usual weekend off. So sure was General Short that Admiral Kimmel's (actually non-existant) long ranged PBY patrols would provide him with adequite warning, that he sent home the very men that were supposed to be watching from above to defend Oahu from seabourne invasion.

Can you imagine the telephone calls made to the Oahu police just befor sunrise ? "Yes sir, and how many Saturday night beers DID you have before you saw the entire Japanese Fleet sailing by just off of the end of your boat dock ?"
"Sure sir, we'll be right over to check it out, sir."
"Yes indeed, right away sir". Click.

My ATL Japanese landing troops would carry a few silenced pistols within the lead elements of each landing party, with one or two English speaking troopers being in American uniforms so that any accidental encounters with real Oahu Americans might be resolved quickly, and quietly.

Once ashore most would be ordered to find cover while using their night infiiltration training to carefully move into their assigned dawn attack positions.

Two groups however would be met by Japanese agents from the Honolulu Consulate, driving closed box trucks rented privately for the weekend.

One group of JSNLF troops (with a few demolition trained combat engineers assigned) from Oahu's western shoreline would be thus driven some three miles thru the pre-dawn darkness to the edge of Fort Barrette which was the home of 2x16" American CAC guns watched over by only a few anti-sabotage sentries. The American guncrews were actually billeted some 12 miles away and were themselves trucked to man that battery after breakfast each morning. Today would be much different.

Another JSNLF group landing on the Kaneohe Plains would also be met and similarly trucked 1,800' up Highway #61 to the summit of the Pali Pass, the ONLY over the Koolau Mountains road connection between Kaneohe Bay and the still slumbering City of Honolulu at that time. Once there the JSNLF troopers would deploy in highway ambush positions, set up their heavy radio (and it's generator, fuel supply and batteries) and dispatch small patrols into the darkness, both north and south along the Koolau ridgeline. Once those reached the first weekend unmanned CAC observation bunkers, the buried 25 pair telephone cable that connected all of the CAC's observers with their coastal defense guns, deployed far below, would be quickly cut. All done well before the 0606 surise.

There are other objections to the feasibility of a successful Japanese invasion of Oahu on December 7th., but I'll let you figure this one out before I dump them on you.

Perhaps you might actually read my ATL plans before wasting any more time ?

 

Devilsadvocate responded with more,

This BS doesn't hold up to any close scrutiny. The Japanese seldom made landings against defended beaches,

Which is exactly why I specified undefended beaches.

and when they did they invariably got into trouble. The initial Malaya landings were against a beach defended by a half-trained Indian brigade armed with rifles and a few machine guns, yet they came within a hair of being repulsed. They succeeded only when the British commanders lost their nerve and ordered a retreat. The landings against the beaches on the Bataan peninsula were all annihilated to the last man, The landings against Corregidor were badly botched and proved extremely costly, they succeeded only because the defenders were badly demoralized by their situation.

Yet, they still won didn't they. There is always back and forth in almost every battle. Such is war. But the winner is the one who quits, last

The initial landings on Wake were repulsed with heavy losses.

There were no initial landing attempts even made during the Wake Island #1 fighting. The Japanese warships were driven off by coastal defense gunfire and some good bomb hits well before any Japanese troops even tried to board their landing barges.

The Japanese may have been good at making assault landings against Chinese peasant conscripts, but when they had to face defenses like those on Oahu, they were in deep trouble. In the first six months of the war, with few exceptions, the Japanese were successful largely because they were, in effect, expanding into a military vacume.

Smart of them wasn't it.

Yeah? Well, how do you explain the fact that every time the Japanese came up against the US Marines on anything like an equal basis in 1942, they lost?

AFAIK there weren't any equal basis battles against the Marines in 1942. The Japanee were almost always low on food, ammo, air support and radio sets. And of course, we all know that the US Marines were supermen too,

What the Japanese had going for them was years of intelligence that told them where to attack so that they wouldn't meet heavy opposition.

Exactly the ATL sceanrio that I have tried to design for an Oahu invasion

When they had to improvise after their "First Phase" operations ended, they were pathetic.

What better reason for the Japanese Empire to aim for a short war against the Americans, as I have been saying all along ?

 

Dabrob, I think you will fit in just right here

 

Your plan is "Island Hopping" in reverse.

So what beaches would the Japanese land on?

If the Marines at Wake repulsed an IJN landing force why wouldn't the Oahu defenders be able to do the same thing?

The Japanese were beaten at Midway and almost beaten at Wake why would you expect them to be any more successful attacking a larger target?

I think the Japanese knew that invading Hawaii would have been too costly and a "raid" on Pearl Harbor was the most effective way to accomplish neutralizing the American fleet.

 

T. A. Gardner typed,

While I had this massive response, it seems the system has eaten it.

The same thing just hapened to me. Damn.

The IJN did not practice using floatplanes from their ships for gunnery spotting either against shore targets or at sea. These were intended for scouting. So, the battleships are firing off a map as they did at Guadalcanal. Gunfire support of naval landings was not something the IJN made a habit of practicing. So, the likehood is that their efforts in this area would be like they were elsewhere:
They would fire far too few shells to be effective.
They would largely leave the target(s) undestroyed.
They would grossly exaggerate the effect they had.
The result would be the landing troops would be hosed by the defenses.

If you were to read on and around page #260 of the 1997 Peattie & Evans book titled "Kaigun: Strategy, Tactica and Technology in the IMPERIAL JAPANESE NAVY 1887 - 1941" you would find that you are completely mistaken in your just expressed PoV. At that time the IJN was probably the best in the world at very long ranged, aircraft adjusted, indirect, heavy calibre naval gunfire. Their "Decisive Battle" plan had depended on it for decades to help in bridging the gap in battleship numbers imposed by the Washington Naval Treaty.

As for the coast defenses:

I think that you'll much prefer my listing instead:

Weapons on hand, Oahu, Dec 6th (PHA Vol 23, 2017) with corrections

Type...................Authorized..............On hand
16" ..BA.......................4..........................4
14".DC.........................2..........................2
12" DC.........................0..........................2
12" BA.........................2..........................2
12" Mortar....................0.........................20
8" fixed........................2..........................2
8" rail..........................12........................12
6" DC..........................2...........................4
3" Coast, fixed.............0............................4
155mm.gun.................24.........................36
240mm..how................0..........................12
155mm...how..............24.........................24
20mmAA.....................12..........................0
3" AA(fixed)................26.........................26
3" AA(mobile).............60..........................60
75mm M1897 ............16...........................16
75mm M1917.............72...........................64
37mmAA...................74...........................20
37mmAT..................160..........................18
37mm M1916 INF........0............................54
81mm Mor................68............................68
3" trench Mor.............0............................32
60mm Mor................150.........................150
Cal 50 AA................166..........................107
Cal 50 MG................185...........................12
Cal 50 MG................52..............................0
Cal 50 MG.................17...........................17
Cal 45 SMG.............524............................21
Cal 30 MG...............375.........................1504 **
Browning Auto.........1929........................2448

Some smaller items are still missing such as the US Army's 4.2" chemical mortars not yet listed.

However, to get an idea of the real state of Oahu's defences back then,
two more columns need to be added, the number of guns that actually had trained crews available to fire them AND which guns were actually deployed in their firing positions on the morning of Dec.7'41.

For instance, of the 36 + 24 = 50 x 155mm on Oahu that morning there were only guncrews for 24 at any one time. And on that peacetime Sunday morning NONE at all were field deployed out on their circular concrete "panama mounts". Not a single blessed one since it was the weekend and live artillery was NOT left lying around unattended in the field where it might be sabotaged.

The 37mm AA guns are another example. 20 had arrived on Oahu but by Dec.7'41 none of their ammo had arrived and no Americans were yet trained in their use.

Of the old 3" AA guns, 26 were indeed permanently installed (in groups of 4 usually or 2 sometimes) in firing positions inside of US Army bases on Oahu but each only had one (1) locked ammunition box of 16 rounds at the gun. The rest of their ammoo was locked up in the Aliamanu Crater Ammunition Depot as per General Short's anti-sabotage orders.

NONE of the 60 mobile 3" AA guns were field deployed on that dreadful morning since Kimmel had not warned Short that an enemy was near to Hawaii.

It goes on and on and on ... the deeper you dig, the more crap that you find.

Much like an apple which can look good on the outside while still being rotten to the core.

Which brings me to the 12" mortar issue. My readings indicate that the American 12" seacoast mortars exclusively fired high trajectory AP rounds intended to pierce the thinner topdeck armor of any attacking warships.

On Corregidor at least, those AP rounds, when fired at Japanese ground troops, simply punched deep into the soil before exploding and did VERY LITTLE damage at all, as a result. Why then do you repeatedly insist that Oahu's seacoast mortars would do great damage to my ATL Japanese invasion troops ?

I'll provide an Oahu battery listing next week as I am now late for a heavy date with a fishing rod, several trout and some cold beer ...

 

Whats the betting someone may just have seen em coming at some stage....Its one thing to launch a surprise attack from the air...Its another to sneak in a massive amphibious landing and hope it works...Yes in Malaya round back of Singapore..and others...but I think Jugheads former comrades of years gone by, may just have said hold on a doggone darned minute....

 

Thanks but alas I fear, not.

I am a "one trick pony" knowing much about Oahu, some about the Pacific/China War and not much else about WW2.

A specialist posting to a discussion board populated by many posters who believe that they know everything ... LOL.

 

That is indeed the most usual reaction.

And I am sure that it was just the same inside of Pearl Harbor at 0756 on Dec.7'41.

AFAIK. the size of the incoming force changes not a historical thing when there were NO Americans looking for one at all.

The OTL history is full of instances when an early warning of the incoming Japanese air attacks on Pearl Harbor COULD have been sounded, yet NONE AT ALL were. I think because the American defenders of the day could just NOT bring themselves to believe that Oahu, the "Fortress of the Pacific" could be attacked at all, LET ALONE by the scrawny little Japanese, while the battleships of the Pacific Fleet were MOORED inside.

Yet the OTL Japanese did it all the same. Foolishly as it turned out 4 years later but in 1941, who could know what would come to pass ?

Save, I suggest, for Yamamoto ...

IMO, with the Allied oil embargo in place, the Japanese Empire was already dying and had little more to loose by going out fighting.

 

Not at all old chap....Not everything....If there is something I dont know, I'll gladly hand over to Wtid45....He will cover the gaps...

Most of us learn lots from this place, and gladly thank those that change our interpretations on some matters we think we knew about.

For instance, I never knew, Germany could so easily have overcome the British in 1940, or Gibralter fell to the enemy, or even that Germany never lost a battle whereby their units had a majority of Germanic accents and not Russian.

Pearl harbour was just a fly in the ointment of ww2. In fact the war never started till 1941.

Monty raced south through the Ardennes to save the surrounded US troops in 44 and if only he had himself put on a parachute and jumped out of a dakota then market garden would have been won.

We learn lots on here...We need more factual knowledge at times though...so stay on board old chap.

Wtid45 will fill in any knowledge you may lack on the Brecon theatre of operations. Thats a place in Wales the Welsh invented to make the English tough enough to win world war 2.

 

Urqh is well and truly back

 

formerjughead observed,

Your plan is "Island Hopping" in reverse.

I hadn't thought of it that way but yes, it is. Just as the OTL Japanese historically did themselves during the first 6 months of the Pacific War.

So what beaches would the Japanese land on?

One 17,000 ton cargo-liner anchors in the darkness just off of Bellows Field, another at the southern end of the barrier reef protected Kaneohe Bay. Both inside that Bay if the wind/waves/surf are bad off Bellows.

If the Marines at Wake repulsed an IJN landing force why wouldn't the Oahu defenders be able to do the same thing?

If my ATL surprise is accomplished, the 22,000 packed in US Army troops asleep in their Quadrangle bunks at Schofield Barracks will be hit by the aircraft adjusted 16" and 14" gunfire of two IJN battleships. With another two BBs in reserve should the HE ammunition run low. Thousands will die before even getting out of bed, let alone getting to their unprepared beachfront positions, which my IJA and JSNLF troops had already crossed in the darkness, several hours before.

Look at a 1941 highway map of Oahu. Aside from the coastal ring (2 lane only) highway there are VERY few roads over which American troops can move their heavy artillery from Schofield/Shafter to the many potential landing beaches. And even an IJN destroyer could interdict any American movement at all along the coastal highway, often built so close to the ocean that salt spray fell on the pavement on windy days.

There will be savage ongoing fighting to be sure but I MUST get my 1LW Japanese ashore to seize commanding terrrain positions while the peacetime American defenders are still stunned and reeling from the ongoing KB and CF attacks. A second IJA division will follow ashore on the next night, Dec.7-8'41.

The Japanese were beaten at Midway and almost beaten at Wake why would you expect them to be any more successful attacking a larger target?

No surprise in either case.

The Americans at Midway greatly benefited by their code breaking advantage at Midway AND by then had 6 long months of combat to "get the cobwebs out". 'Twouldn't be that way on a still peacetime Oahu on Dec.7'41.

Wake #1 was a fluke as happens in all wars. First, Wake #1 happened well AFTER Dec.7'41 so that the American defenders there at least KNEW that they were at war with the Japanese. A Japanese air raid some hours previous had alerted the Americans that "something was happening". The American CAC gunners hit the supporting light Japanese warships well and an aircraft bomb set off some Japanese torpedoes (or was it depth charges ?) on deck. The landings never even got started as the Japanese force sailed away to rethink the situation

I think the Japanese knew that invading Hawaii would have been too costly and a "raid" on Pearl Harbor was the most effective way to accomplish neutralizing the American fleet.

Clever of you to agee with the historical record but why do you then bother to post to a "what IF" board ? The historical record leads to the defeat of the Japanese Empire, as Yamamoto surely well knew even BEFORE the bullets started flying.

The point of my ATL Invasion Hawaii scenario is to discuss how the Japanese Empire MIGHT have just squeaked thru and survived a short war with America, instead.

 

The odds are extremely high that a two-division landing force, proceeding in convoy, would be spotted by aircraft or vessels before they could close to within 100 miles of Oahu. There may not have been any regular patrols far from Oahu, but there were numerous military training flights and commercial flights among and around the Hawaiian islands in 1941. In addition there were dozens of naval and commercial vessels plying those waters, any one of which could easily have spotted a convoy of that size. I'm not saying that it absolutely would have happened, but the risk was definitely very high that it could happen, and military planners don't accept high risk factors.

See; USN Pacific Fleet Ships Not At Pearl Harbor

There is no way that the Japanese IGHQ is going to invest so much time, and so many resources, and risk so much when the odds of some random event ruining everything is so high. Dabrob forgets that the Japanese Army ran things, not Yamamoto. Yamamoto may have been a gambler, but he wasn't insane, and neither was the Army General Staff nor the IGHQ. No way would they approve such a fantastical scheme.

Moreover, Dabrob heavily overestimates the capabilities of the Japanese military in making assault landings over defended beaches. The idea that that more than 10,000 troops could secretly be landed on such beaches in complete darkness is nonsense. My brother-in-law (my wife's eldest brother) witnessed, as a 12 year-old boy, the Japanese landings at Miri in December, 1941. At that time, he was living with his family just south of the town on a hill overlooking the landing beach. The Japanese landing force arrived in several ships at about 2:00 AM, and the noise of the anchor chains running out as they anchored awoke his family. They watched as the Japanese spent several hours launching boats, loading troops, yelling orders, shooting off red and green flares, and generally making a huge commotion among much confusion. Of course, the landing was mostly unopposed, but the Japanese, at that time, had no idea of Miri's defenses. The Japanese assault troops began landing at first light, and by then everyone in the town was aware of the invasion, and many people had fled into the jungle.

It is generally impossible to put a large number of troops on a beach without making a lot of noise. And that, given the situation on Oahu in December, 1941, would guarantee that with the dawn would come an intense air and naval attack on the Japanese landing forces. It's usually conceded that an assault landing cannot prevail under air and/or naval attack.

 

I'd go along with DA again here...I try not to make a habit of such things but he is infuratingly correct again in my view.

They would have had as much success if they had done a two pronged attack...with one heading for California and maybe in unison with Nazi's who could have arranged to land on British beaches at same time, and surprise the lot of us, our fathers and grandfathers all asleep at the end of the piers as the boats tied up.

 

urqh replied with

Monty raced south through the Ardennes to save the surrounded US troops in 44 and if only he had himself put on a parachute and jumped out of a dakota then market garden would have been won.

I knew THAT already. LOL !

...so stay on board old chap.

I certainly intend to but I'm just not sure of how much I'll be able to intelligently contribute to non-Oahu subjects.

Wtid45 will fill in any knowledge you may lack on the Brecon theatre of operations. Thats a place in Wales the Welsh invented to make the English tough enough to win world war 2.

My mother is English and I've been bodily THROWN out of two pubs in Haye-on-Wye so that should count for something, shouldn't it ?

 

Dabrob....You are definately most welcome....Hay On Wye...Put the canoes in and off to Monmouth...many a serviceman has done that route...and I saw my best mate thrown out of a pub in Hay once....we would have gone with him, but it was market day and beer was half price....priorities and all that...

Welcome aboard.

 

The 37mm ammuntiion had arrived. Unfortunately, it was still aboard ship in Pearl Harbor, awaiting unloading. Re: "the 12" mortar issue." Your readings are highly incorrect. Those 12" mortars fired both AP and HE mortar shells. Granted, there weren't nearly enough of the HE shells on Corregidor, but Seaward Defense Commander Paul Bunker devised a plan to convert the AP rounds into HE by removing the 0.5 second delay pellet from the shell, making it into an instantaneously bursting mortar shell. Those 670-lb shells worked all too effectively against the Japanese during the siege of Bataan's "Battle of the Points" and later, the siege of Corregidor. So you see, those seacoast mortars could and would do great damage to "your" ATL Japanese invasion troops.

Lastly, all of your horse drawn artillery would be without horses as all of them would either be seasick and incapacitated for several weeks, in the act of dying from shipboard fever or already dead from the long sea voyage. Horses die like flies after long periods of being pent up in a closed environment.

 

A 10 knot naval convoy covers 200 nm in 20 hours. This means the Japanese in order to land their main force will either have to do so many hours after the first attacks take place or, they will have to risk being spotted at sea long before they arrive.
Even a force sailing at 20 knots covers this distance in 10 hours and risks detection.

As for taking out the coast defenses:

First, the Japanese don't know were everything on Ohau as far as coast defense is located. They have the major fixed batteries and forts but know little of the mobile defense systems like the 155mm guns, 240mm howitzers, 8" rail guns, 12" rail mortars and many of the smaller positions. They also have only a sketchy knowledge of the fire control systems and their locations.
This the US found out later from captured maps and intelligence gathering during the war.
The US fire control system in 1941 included both remote and co-located fire direction towers and positions. There were central plotting locations at the major batteries that could direct the fire of both their own guns and those at other locations. The Harbor Defense of Honolulu Command Post was on Diamond Head in an underground facility inside Fort Ruger for example. The system also had radio as well as telephone communications available.

Then there are just numerous military bases and installations all over the island including:
Fort Weaver
Fort Kamehaheha
Fort Shafter
Fort Armstrong
Fort De Russey
Fort Ruger
Schoefield Barracks
Wheeler Field
Bellows Field
Haleiwa Field
NAS Kaneohe
NAS Barbers Point
Ewa Field (USMC)
Hickham Field
NAS Ford Island
Mokuleia Field
Among others.

These are scattered over the entire island. This too is a problem.

Then there is the issue of where to land. Much of the coast of Ohau is unsuitable for an amphibious assault. Were beaches are suitable the US did place some defenses to quite a bit of defense. Any attempt to land on the south (eg., Pearl Harbor) side would also have run into the standing destroyer picket in the "submarine exclusion zone" just as the Japanese midget subs did. Sinking of the Ward or other US ships moving in this area is possible but not without their almost certainly warning Hawaii it is under attack.

We also know from the amphibious assaults the Japanese did make that they were less than efficent in unloading and then running into the beaches. This too has been pointed out.

The overall picture is one that they may have been able to muster the forces to make such a landing but it was going to be a rough fight to take the island and very near impossible that they could manage a win out of it.