What does the IJN look like if war delayed six months?

[Admiral Beez]

If the attack on Pearl Harbor does not occur until June 1942, what does the IJN look like? With both oil becoming short and new vessel construction completions, what ships and aircraft are active? Also, by June 1942 what do defences in Malaya, Burma, Philippines, DEI and Pearl Harbor look like?

The situation for Germany in both North Africa and Russia by June 1942 isn't looking good. Japan's embassies in Berlin and Moscow can clearly see.

 

[Thumpalumpacus]

PH and PI will have more airplanes. PH will base more ships, and perhaps Cavite will as well. Wake and Midway will likely have stronger defenses too. PI will have more time to train the local troops, though to what effectiveness may still be very doubtful. They will have more airplanes, and hopefully better planes too.

DEI is still going to be weak -- lack of replacements, spare parts, etc. They will get the fighters being sent, and have time to train up in them.

Malaya and Burma will probably have better air defenses, but for ground troops, it's hard to say. Force Z, if it's sent at all, probably stays at Ceylon to be the nucleus of a reinvigorated Eastern Fleet? If Australia doesn't feel threatened, do they demand the divisions from the desert back at all?

 

[Zmauky]

Probably the only way to delay Pearl Harbor is for Japan to have access to oil.
I am almost certain that Japan would not make a "Molotov - Ribbentrop" variant of the agreement with the USSR so that the oil from DEI and Southeast Asia remains only option. Now this is where things get interesting. If Japan were to enter the Dutch East Indies as in French Indochina (possibly with the consent of the Dutch government under the tutelage of Germany without war), it is a reasonable assumption that the US Congress would not vote for a declaration of war (probably even if Japan attacked the UK in same time ). Admittedly, a war between the USA and Japan (and Germany) is inevitable sooner or later. But how it would develop is the question. With a little less American enthusiasm (at least according to Gallup polls) and perhaps without Yamamoto's sabotage of the general Japanese war plan. (ie decisive naval battles with the help of aviation in their own waters).
How would the US media react if FDR (through the senate, of course) declared war on Japan, and then lost the fleet near the Philippines? And without a fleet, all US reinforcements of bases and the Philippines do not mean much.

 

[Shortround6]

If Japan were to enter the Dutch East Indies as in French Indochina (possibly with the consent of the Dutch government under the tutelage of Germany without war

Trouble is that Queen Wilhelmina had set up a government in exile in England in May of 1940. There was no equivalent to the French Vichy government to give permission or agreement
to a Japanese occupation of the DEI.

We also have to believe that the Japanese are going to bypass the Philippines and the hundreds of aircraft and dozens of US ships stationed right astride the Japanese supply/trade lines and depend on the US isolationists to save the Japanese from attack for several years to come.

 

[Shortround6]

The situation for Germany in both North Africa and Russia by June 1942 isn't looking good. Japan's embassies in Berlin and Moscow can clearly see.

Japan may give up? No war?

Now the US entry in WW II was not 100% dependent on the Japanese. The War in the North Atlantic was heating up. Unless the US pulled back there were going more incidents between US escorts and German U-boats. German U-boats depth charged. American Destroyers/escorts torpedoed. American merchant ships sunk.

The Japanese can also see the US fleet build up. The US Pacific fleet is not going to get weaker in 1942.

From Dec 7th 1941 to June 30th 1942 the US commissioned 15 Gleaves class destoyers several escort carriers and 3 South Dakota class battleships, I haven't checked the cruisers yet.
Now it took a while to go from commissioning to fully operational but the US fleet was getting stronger by the month.

As far as aircraft go, in fighter the US had around 160 P-38s on Dec 7th, they had built 74 in Nov so if we allow for 70 a month for 6 months that is 420 ( they actually built at least 100 a month in the first 6 months 1942). Conservative estimates of other fighter production would be around 480 P-39s in 6 months, around 1700 P-40s and at least 240 F4Fs.
All of these are hundreds lower than real production.
No idea of the bomber build up.

Edit> laid down but not completed, 19 Cleveland class light cruisers until June of 1942. Some converted to light carriers. All public record.

 

[Admiral Beez]

No one wants to posit on the IJN of June 1942? For example, we have two Hiyō-class aircraft carriers entering service by this date.

List of Japanese Navy ships and war vessels in World War II - Wikipedia

en.wikipedia.org

 

[Thumpalumpacus]

No one wants to posit on the IJN of June 1942? For example, we have two Hiyō-class aircraft carriers entering service by this date.

List of Japanese Navy ships and war vessels in World War II - Wikipedia

en.wikipedia.org

Fuel to run the IJN has gone down by six months', leaving ~12 months or so for ops. Yamato's fully worked up, but even a bigger fuel hog.

I think the Japanese struck when they did because they felt the sands of time running out.

 

[Shortround6]

No one wants to posit on the IJN of June 1942? For example, we have two Hiyō-class aircraft carriers entering service by this date.

The Hiyo's are converted ocean liners. They are slow, poorly compartmented below decks, and can hold 50+ aircraft each. Better than 30 plane carriers but in this scenario the US has no losses from Coral Sea or Midway or torpedo damage to the Saratoga.
5 big fleet carriers and the two small ones in the Atlantic?
And 3 to 5 Essex class laid down in 1941 or very early 1942. The avalanche is coming.

 

[EwenS]

The Japanese were not so stupid as not to know very well that the avalanche is coming. They knew they could not outbuild the US in ships, hence the shadow carrier programme to convert auxiliary and merchant hulls to carriers, the largest of which were the Junyos.

But looking at historical build times for larger USN ships gives a completely false impression of what was being planned in late 1941.

The reality on 7 Dec 1941 was that with peacetime build rates no Essex was due in service before 1944, the USN was resisting FDR's call for CVL conversions of light cruiser hulls (finally approved Jan 1942), and production of CVEs (The only CVE under construction in US yards to join the Long Island originated from British orders, with Britain giving up Charger for the USN training role, including that of FAA pilots. The 20 Bogues, half for the RN, were only ordered after PH with only 1 in service by the end of June 1942 . A British request for more had been turned down in mid-1941 due to a lack of suitable hulls).

Somewhere I have the BuShips monthly reports to FDR for Nov/Dec 1941 showing the planned build programme which I will try to find and post. It covers everything coming out of the big 1940 expansion.

As for British reinforcement of Malaya, forget the historical. So much changed with the Japanese invasion. For example the 18th Div was destined for the Middle East until diverted. The Hurricanes that ended up in the DEI and India/Ceylon from Jan 1942 were intended for Middle East. Australia only requested the withdrawal of its 3 Divs from the ME in late Dec / early Jan (Churchill persuaded them to leave the 9th). Britain had decided the ME should have priority over the FE. That wouldn't change without some monumental change of relations with Japan.

The USN will not be moving much forward from PH to the PI. Maybe the odd cruiser. Nothing larger. Why? Because they can't support it, without access to Singapore, something they had rejected in early 1941 as that would be seen as aiding the imperial European nations (largest dry dock in PI was cruiser sized). Also they lacked oilers capable of RAS (Pacific Fleet had 4 in Dec 1941).

I have details somewhere of Admiralty plans for FE deployments by April 1942, which I'll dig out.

 

[EwenS]

No one wants to posit on the IJN of June 1942? For example, we have two Hiyō-class aircraft carriers entering service by this date.

List of Japanese Navy ships and war vessels in World War II - Wikipedia

en.wikipedia.org

The completion, or completion of conversion, of IJN ships would run pretty much as historical due to pressure on Japanese industry. However, when in Nov 1941 the decision was taken to go to war, some ships under construction were halted to later be broken up on the slips. So delay war for 6 months and they are a bit further along, but not enough to change anything in 1942. For example

4th Katori class training cruiser Kashihara laid down Aug 1941est completion spring 1943. Suspended Nov 1941.
2 Ibuki class cruisers ordered Nov 1941, laid down April & June 1942. But completion as cruisers or oilers or carriers is still a long way down the road.

May be a few of the merchant hulls planned for conversion to CVE survive long enough for that to happen, joining Taiyo and Unyo. But again probably 1943.

 

[mack8]

Also generally more modern planes in carrier and landbased units, replacing older A5M, G3M, older floatplanes etc. Shoho and Junyo have full airgroups of modern planes.

As for ships, if the war starts later would the 1941 emergency program be adopted in the first place? Maybe, but later, as that was a consequence of the decision to start the war. So possibly Niyodo is laid down as planned first. Shinano and No.111 might be further along. Maybe without the pressure of the OTL war preparations and the war Akagi would have received the 12,7cm AA guns before mid-1942. And the first radars are mounted oon IJN ships, maybe on carriers rather than BBs?

Same goes for IJAAF re planes, more modern types in frontline units like Ki-43, Ki-44, Ki-48 etc.

 

[mack8]

Interestingly, come to think of it the IJN carrier situation re the USN might actually be better by mid-1942, with Shoho and Junyo operational, Hiyo and Ryuho joining soon, and modern planes aboard. And couple of CVEs, though not sure what the USN situation would be re CVEs. Hornet is also operational, but imo the US carriers will still fly TBDs by mid-1942, since without war pressure production/replacements arrive a bit slower?

Plus the american CVLs might be ordered later hence the IJN situation would be better than OTL until late 1943/early 1944, since not only the first Essexes arrive a bit slower, but the CVLs are delayed say 6 months or more as well.

 

[EwenS]

Now found that BuShips report. It is attached below. It includes everything down to PT boat level. Page 3 of the .pdf has a summary of the expected completions year by year ro 1946. Some points to note:

1. Note this report uses their originally allocated names. Particularly noticeable with the Essex class. CV 16 Cabot became Lexington with the original name allocated to a CVL in 1942.
2. Despite the huge orders in 1940, note how many hulls had still to be laid down at 1 Dec 1941.
3. They managed to cut 3-6 months off the expected completion dates of the South Dakota class AFTER PH
4. Note that the Montanas weren't going to be laid down before late 1942 (see contract completion date & build time). They had to await completion of the dry docks they were to be built in.
5. The only carriers on order are the first 11 Essex due to complete 1944/45. 2 more were ordered immediately after PH as a reaction thereto with 10 more in Aug 1942 post Midway.
6. Only 8 CL due to complete from Oct 1941 - Dec 1942 (4 Atlanta & 4 Cleveland all laid down in 1940). Historically they only managed to complete 9.
7. The planned 14 CL completions in 1943 was sacrificed by converting 9 hulls to CVL from early 1942.

If the war with Japan gets delayed by 6 months, I see nothing to force a significant change to USN plans. So the speeding up of construction just moves to the right. The USN will continue to resist FDR over CVL & CVE programmes (note there are none included in the attached report) as I noted above.

As the big gun is still king, note how the battleship and cruiser programmes have a higher priority than the carriers. The USN was particularly short of modern cruisers (18x8" and 9x6" Treaty ships plus 10 old Omahas good only in lesser theatres) to cover its worldwide, and expanding, commitments.

With regard to carrier availibility, the Lexington & Saratoga had been scheduled for a long list of modernisation items (it ran to 24 different groups of items) that had constantly been postponed since Sept 1939, and were only to be carried out when the ships were available during routine yard periods. Saratoga spent most of 1941 under modernisation & refit but it was only after she was torpedoed in Jan 1942 that the most significant items were carried out (adding bulge, removing the 8" turrets etc). Lexington was due her next yard period starting in May 1942. How long she would be out of service for would very much depend on exactly what work it was decided to carry out on her.

It also should be remembered that while the US did not wish to be seen openly assisting imperial powers in the Far East, they were prepared during 1941 to expand their activities in the Atlantic, thereby releasing RN ships for the Far East. One sign of this was the escorting of convoys to the Mid Ocean Meeting Point south of Iceland. And that involved vessels up to battleship size. So it is by no means certain that new completions would go straight to the Pacific. It was only after PH that Yorktown was sent to the Pacific, leaving Ranger, Wasp and the working up Hornet in the Atlantic. That alone made it more likely that the US would be dragged into a European war in 1942 as incidents with US boats were bound to increase.

For the RN mid-1941 saw it looking to build up a Far East Fleet, courtesy of the US assistance noted above, by April 1942 that would have been based around Nelson, Rodney, 4 R class, Repulse & a carrier (probably a refitted Ark Royal). Of course a lot conspired against that plan. Nelson was torpedoed in Sept 1941 and was out of action until April 1942. Ark was sunk in Nov 1941. The decision to send Repulse & the 4 Rs predates the decision to send PoW. Repulse left Britain at the end of Aug 1941 and the Rs followed as they completed refits.

The decision to send PoW, and to use it and Repulse to form Force Z, dates to the end of Oct 1941. That was of course after an increase in the threat level following the occupation of southern French Indochina at the end of July 1941. So in any scenario, when does Japan make that move?

 

[Admiral Beez]

Due to new ships entering service, would some of the IJN's older vessels go into reserve or training status? For example, Hōshō's CAG goes to the Hiyos?

As for British reinforcement of Malaya, forget the historical. So much changed with the Japanese invasion. For example the 18th Div was destined for the Middle East until diverted. The Hurricanes that ended up in the DEI and India/Ceylon from Jan 1942 were intended for Middle East. Australia only requested the withdrawal of its 3 Divs from the ME in late Dec / early Jan (Churchill persuaded them to leave the 9th). Britain had decided the ME should have priority over the FE.

If much of what was historically sent instead goes to the Middle East and North Africa, it sounds like Britain's land and air forces in Malaya might be worse off, not better with the six month reprieve. The RN has gained HMS Indomitable, Anson and Howe, though the final KGV class commissions just as the PacWar kicks off in June 1942, so she'll need another few months of working up. Does the RN gain any submarines to make up for losses to date? A half dozen placed off FIC with effective ROE would be useful.

Back to Japan. On Dec 5, 1941, the Red Army launched their counteroffensive along the entire front near Moscow, pushing the Germans back 150-300 km from the capital. The battle for Moscow is considered one of the turning points in the Second World War. Do reports that Germany is struggling against an increasingly strengthening USSR force Togo's government to challenge its assumptions and consider alternative directions? Not that Japan had many options. Negotiate with Mao and the communists against the KWT, but to what end? Declare a break from Germany (and Italy) and offer to send destroyers to help Britain - with no Germany DoW against the US, might Britain welcome the help? But then again, perhaps Japan doesn't really care what happens in Europe as long as everyone is distracted.

 

[Thumpalumpacus]

Back to Japan. On Dec 5, 1941, the Red Army launched their counteroffensive along the entire front near Moscow, pushing the Germans back 150-300 km from the capital. The battle for Moscow is considered one of the turning points in the Second World War. Do reports that Germany is struggling against an increasingly strengthening USSR force Togo's government to challenge its assumptions and consider alternative directions? Not that Japan had many options. Negotiate with Mao and the communists against the KWT, but to what end? Declare a break from Germany (and Italy) and offer to send destroyers to help Britain - with no Germany DoW against the US, might Britain welcome the help?

The southern resources still need to be seized for Japan to attain its national goals of economic independence and domination of East Asia. There's no oil in China, and none was known in Siberia at the time. The national stocks are declining all the time due to the American embargo. The only thing that will overturn that would be a withdrawal from China and SEA (per Hull's last offer), and any Japanese politician ordering that is a dead man.

The oil clock is ticking, and that's why the Navy got its way and won a late 1941 start directed south.

 

[EwenS]

Due to new ships entering service, would some of the IJN's older vessels go into reserve or training status? For example, Hōshō's CAG goes to the Hiyos?

In Dec 1940 trials it was found that Hosho couldn't operate Zeros, Vals or Kates (Warship 2008 article). Combined Fleet has her CAG in Sept 1941 as 11 A5M Claude fighters & 6 biplane B4Y1 Jean torpedo bombers. By Midway is was the Jeans for ASW work only.

If much of what was historically sent instead goes to the Middle East and North Africa, it sounds like Britain's land and air forces in Malaya might be worse off, not better with the six month reprieve.

They will certainly not be better off but probably no worse off than historical on 8 Dec 1941 in material terms. 18th Div for example historically wasn't diverted to Singapore until it reached South Africa on 9 Dec 1941 and it was into Jan before it arrived in Singapore. Indomitable lifted the first Hurricanes to Java at the end of Jan 1942.

Six months however does give more time for training both Army units (if jungle training along the lines of the Argyll & Sutherland Highlanders was undertaken, which might be questionable) and RAF units (some of the Buffalo squadrons had not been formed long e.g. 488 formed 1 Sept and arrived in Singapore in Nov 1941 with most pilots fresh from training schools). More time also to extend the radar reporting network, although geographic issues mean it still wouldn't be up to 1940 Fighter Command levels. It also gives more time to try to persuade the civilian authorities of the necessity of improving the defences of the territory.

The RN has gained HMS Indomitable, Anson and Howe, though the final KGV class commissions just as the PacWar kicks off in June 1942, so she'll need another few months of working up. Does the RN gain any submarines to make up for losses to date? A half dozen placed off FIC with effective ROE would be useful.

Anson didn't complete her work up until the beginning of Sept 1942 and Howe until Feb 1943 (although she was considered ready to deploy to intercept any attempted German breakout from Nov 1942).

Indomitable was scheduled to be at Gibraltar by the end of Nov 1941. As we have discussed before, Ark Royal was by late 1941 badly in need of a refit, with her machinery in need of overhaul. Had she not been sunk on 14 Nov she was scheduled to do another Hurricane delivery run to Malta before the end of the month (the aircraft were already at Gibraltar). Indomitable's arrival would have allowed her release to refit. Historically, Argus acted as a stop gap until Eagle arrived in Feb, having had her refit cut short and still with problems (hence the RN need for Wasp in April / May).

Until the outbreak of war in the Far East, the Illustrious & Formidable were headed for the eastern Med to reinforce the Med Fleet. A six month delay would have seen them fully worked up. Depending on what happens in the Med in those 6 months maybe they can be moved through the Suez Canal to the IO on the outbrak of war with Japan.

Better still more of that first batch of 90 folding wing Martlet II (cash purchases arising from options in the French contract) might have been available for them to fill their decks out with. But that last would depend on overall production levels and how the USN was willing to share production priorities. F4F/Martlet production in 1941 totalled 323 aircraft. That level of production was achieved in the first 4 months of 1942 but didn't exceed 100 airframes until May. But without the US at war just how quickly does it ramp up? Will the US allow the follow up Lend Lease Martlet IV deliveries to start sooner? Remembering that the USN itself badly needed to modernise its carrier aircraft fleet (it was the latter part of 1941 before the last biplane fighters were retired).

As for submarines, the only class suitable for Far East deployment at the time were the T boats. (This was before extra oil capacity was being added to the S class boats to allow their use east of Suez). Only 1 T boat completed in the first 6 months of 1942. In the same 6 months they lost 2 T boats.

As discussed before on ther threads, the RN did not release any submarines from the Med for the Far East until late Dec 1941 / early Jan 1942. Then it was but 2 T boats.

Britain had decided that the Middle East should have priority over the Far East. There has to be a monumental shift of policy as a result of some external event before that is going to change. Historically that event was the Japanese invasion of Malaya. What event do you foresee happening in this 6 month grace period that might provide that kick start?

 

[SaparotRob]

If there is cash available, might Grumman be persuaded to keep Bethpage running? I could see the USN appreciating that.

 

[EwenS]

If there is cash available, might Grumman be persuaded to keep Bethpage running? I could see the USN appreciating that.

I don't follow you. Bethpage switched from F4F to F6F production between Sept 1942 & May 1943. TBF production went on until the end of 1943.

The deal with Eastern Aircraft Division of GM is interesting. The order to stop car production in the USA was issued on 12 Dec 1941 in the aftermath of PH. With a few twists and turns, it was agreed that they should build the TBF (as the TBM. Production started Nov 1942) and the F4F-4 (as the FM-1. production started Sept 1942). Contracts were signed early Feb. I found this but have still to read more than the first few pages of Part I.

A History of Eastern Aircraft During World War Two

A collection of broadcast equipment manuals, catalogs, radio station pictures and broadcast information.

www.steampoweredradio.com

But with no PH, there is no stoppage of car production so using that industry moves to the right. Perhaps it means that when it does start it is with the FM-2 (an Eastern Aircraft version of the F6F)

Grumman production of the F4F peaked at 190 in the month of Nov 1942 but it wwas Nov 1943 before Eastern reached that production level. In Nov 1943 Grumman knocked out 400 F6F.

 

[SaparotRob]

Thanks for the clarification, EwenS. I kinda' think of Bethpage as synonymous of Grumman. It's about 10 miles from here. (That and I completely spaced on the F6F switchover.)
What I did mean was if the demand was there wouldn't some facility be found? If Pearl wasn't attacked, even though the U.S. was ramping up aircraft production, the demand might be less if the 'States wasn't actually at war.

 

[Shortround6]

US production of all kinds of things would be delayed by the Japanese waiting 6 months. The question is how much and even if Japan was out building the US in those 6 months.
Was Japan getting stronger or weaker in relative strength?

And the Numbers do not look good for the Japanese. For example

The Japanese built 325 Ki-43s from Dec 1/41through June 30th/42
The Japanese built 573 A6Ms from Dec 1/41through June 30th/42

US P-40 production was averaging just over 270 planes per month in the fall of 1941. In 4 months of 'peace' time production the Curtiss alone built more single seat fighters than Japan did in 7 months after the start of the war.

The Avengers would have been a bit later, but since the production contract for 285 of them was signed Dec 30th 1940, it would be a matter of a few weeks.
June of 1941 had seen the contracts for the two Prototype F6Fs signed the same day that Chance Vought got a contract for 584 F4Us. Six-seven months of peace might have caused them to be later but.......Brewster was signed up to be 2nd source on Nov 1st 1941. Goodyear was signed up in Dec, before or after PH?

Doesn't look good for tanks, or artillery or other army supplies/equipment.
ACF was building over 210 M3 light tanks a month from July 1941 on.
The M3 Medium was being tooled up the fall of 1941 with both different engines and different hull construction (riveted, welded, cast) PH may have speeded thing up a bit but all of the production planning was done and different engines types tested and so on.

What took longer to fix was US tactics/doctrine/training.
But in sheer numbers the Japanese were never going to be stronger than they were on Dec 7th compared to the US.