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.........AT L
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 ?