Indian Ocean 1942 - Somerville's trap works

On 26th of March 1942 a powerful force of six carriers and escorts under Admiral Nagumo left Celebes for the Indian Ocean to raid Colombo on Ceylon.

The British Admiral Somerville commanding the British Eastern Fleet intercepted the expected Japanese arrival (1st or 2nd of April) at Colombo and moved the fleet to Addu Atoll in the Maldives to from here launch a night air strike on the Japanese force and quickly withdraw before dawn. The British Eastern Fleet had three carriers Indomitable, Formidable and the small Hermes, but more importantly had radar equipped Albacore torpedobombers trained for night attack. A strike of some 30 torpedobombers would have been possible and against which the IJN would have been practically defenceless. The IJN had no clue of the British force waiting at Addu Atoll, but in OTL they had not arrived at Colombo by 2nd of April and this had Somerville withdraw to the west as the danger of detection grew for each hour. Caught at daytime the British Eastern Fleet would have been dead meat.

So far this is OTL, but now let the PoD be the IJN arriving at Colombo on 1st of April and the FAA strike is launched the following night, catching the IJN by surprise and sinking two carriers and damaging two more. The search parties sent out do not find the British main force already withdrawing at full speed but succeed to catch and sink the detached Hermes and two cruisers. After some retaliatory raids on Colombo the Japanese force withdraws at best speed which is 17 knots with the damaged carriers. The two damaged carriers will need major repair at a main base in Japan and will not be ready until very late 1942 at best.

How will this effect the coming Japanese operations. Will there be a Coral Sea or Midway at all?

What will the Americans do?

What will the British do?

Will Somerville be celebrated as the Nelson of 20th century or be blamed for not finishing the job?

Regards

Steffen Redbeard

Interesting. Somerville the 'New Nelson'? I don't think so. But it would certainly raise the visibility of British Pacific Forces (even if this is in the Indian Ocean) sixty years later. Definately a huge moral boost. Perhaps all the remaining 'Big Gun' Admirals back at the Admiralty will be put out to pasture sooner than later. I would think the Japanese would immediately go on the defensive and at least the thrust towards Australia is discarded.

Midway may still occur since the Japanese (ie. the Combined Fleet in particular) wants to smash the US fleet in order to advance and seize Hawaii.

It partially depends on the details.

If we assume that the British sink the Zuikaku and the Shokaku, which is the best result given the above (and not completely impossible, given that this is a radar directed attack, and these will be the most conspicous targets, and were part of the same divsion), then the Japanese will have lost two of their most modern fleet carriers, and will be down 168 aircraft. There would be very few survivors, and it will leave the IJN hurting for aircrew.

It would be a big morale boost for the British, and would also crimp the IJN's options. It would also validate the tactic for the RN, and they might attempt to develop this expertise.

If they sink two escorts, it would be less significant.

All the six carriers present with Nagumo were major types, but I agree that Zuikaku and Shokaku would be the worst to loose for the IJN. I haven't seen the actual orders Somerville made, but concerning the general experience by April 1942 with IJN naval aviation I think an order to concentrate on the (biggest) carriers would be plausible. Much would depend on how the initial spotting of the target goes. The schedule was radar locating the fleet and flares then being dropped on (behind) the main targets with the torpedobombers following in closely afterwards. This makes the biggest ships the most probable targets, but of course anything can go wrong - or well. The FAA performed these tactics with great success in the Med., also against moving targets (try reading Charles Lamb: War In A Stringbag).

Not to be overseen is that the ATL also includes two carriers damaged. Had it happened in Tokyo Bay, it might not have been a major problem, but the Bengal Bay is very far away from major IJN repair facilities in spring 1942. I considered to have an allied sub meet one of the damaged carriers, but I did not have information on deployment of allied subs in first half of 1942.

But anyway the IJN will be short of four out of six major carriers in most of 1942 - i.e. when Coral Sea, Aleutians, Midway and Guadalcanal happened in OTL. Left will only be two large carriers and the smaller and in some cases slower carriers (IIRC 4-5 by spring of 1942).

In contrast the RN in May had three fleet carriers in the IO (Illustrious class) and the USN would have 2-4 large fast carriers.

I guess the British would be very tempted to start the liberation of Malaya and Singapore right away, but the question is what land forces would be available. Madagascar involved a total of 5 brigades and would be superflous in this TL. 5 Brigades is hardly enough to liberate SEA, but perhaps to be landed as a flank threat to the Japanese army in Burma.

If Japanese (and not capable of seeking peace ASAP) I would focus on keeping Malaya, Singapore and the western parts of DEI. That deletes most of the OTL 1942 battles, but I guess we will see the RN operating in the SE part of the IO and the USN in the South China Sea and around PI (from Australia). The question is if the Americans are that keen on assisting the British in regaining their Asian empire, or just will focus on the PI. That could perhaps leave the Japanese with some tiny windows of opportunity for defeating the allies in detail - at least for some time.

Regards

Steffen Redbeard

If the jap's lost 4 carriers that early on, they would probably would have seeked their "decisive battle" in defense, not attacking an enemy target, like they tried in the Mariannas...
they would probably loose, and even if they won, they still couldn't undertake major offensive operations...

I was wondering if this was after MacArthur left the phillippines. With what I have learned on this site about him, I highly suspect there could be some interesting infighting if this happens, with MacArthur demanding that FDR talk to Churchill about using the excess British to liberate the Phillippies. I can *really* imagine it if he's still holed up there.

I wonder if he could be abrasive enough to get pulled back by FDR? Was "islans hopping" his idea?

I think that this also makes a "Europe First" strategy even more forceful in this TL, because it'll be said that "the British can handle the Japanese easily." Which might also aggravate MacArthur.

Coral Sea wouldn't happen, I thikn the Japanese might try to sentthe slower carrier for something like Midway, but int he end it will be more defensive. And, it may be the British will even end up co-operating with the Americans after all.

Alratan said:

It partially depends on the details.

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It definitely does. To begin with, before going on to the strategic implications, I'd want to know if Somerville lets it go or tries to maintain contact. If I were him, I'd try to, using my Fulmars as snoopers, & try & hit Nagumo again the next night or the night after (as possible). I'd also send word to my local HQ to send subs after Nagumo. I don't know what RN/RAN/RNN had in SWP/Ind Oc, but OTL Christie & Fife had about 20 boats in Oz, at least half on Nagumo's probable route home (Malacca Strait, Borneo, Cam Ranh Bay, Luzon Strait) at any given time, & English could put about as many into Luzon Strait (presuming arrangements to keep Christie's boats out, for fear of fratricide) & off Bungo Suido. They might get enough shots at the TF &/or its crips to sink 1-2 more carriers (unlike the "Wounded Bear" fiasco hunting Shokaku after Coral Sea).

This also potentially butterflies away the Doolittle Raid: Nimitz might send his own 4 CVs (E, Lady Lex, Hornet, Yorktown) to try & intercept Nagumo en route (Battle of the South China Sea?).

Alratan said:

If we assume that the British sink the Zuikaku and the Shokaku...

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This has big butterflies. They wouldn't be at Coral Sea. Would NGS insist on using fleet CVs, or would (say) Ryujo be substituted? I'd say that means Japan loses 2 (small) CVs, instead of one & damage to 2 fleet CVs, while USN possibly loses none, sees 2 damaged, & gets 1 (both?) back in action for Midway. I don't see Yamamoto calling it off...

DTF955Baseballfan said:

I was wondering if this was after MacArthur left the phillippines. With what I have learned on this site about him, I highly suspect there could be some interesting infighting if this happens, with MacArthur demanding that FDR talk to Churchill about using the excess British to liberate the Phillippies. I can *really* imagine it if he's still holed up there.

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An interesting possibility... I doubt Brooke would agree to it, nor Winston; both strike me more sensible, & Germany was the bigger threat. The Ozzies might feel a bit safer, & allow 7h, 8h, or 9h Inf to be deployed to NAf, especially if Coral Sea doesn't come off (which isn't a sure thing, IMO).

DTF955Baseballfan said:

I wonder if he could be abrasive enough to get pulled back by FDR?

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Back to DC? Never. FDR was afraid he'd try & run for President (with reason, despite Mac's disclaimers).

DTF955Baseballfan said:

Was "islans hopping" his idea?

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No. It originated in War Plan Orange.

DTF955Baseballfan said:

I think that this also makes a "Europe First" strategy even more forceful in this TL, because it'll be said that "the British can handle the Japanese easily."

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Never. Not after Pearl Harbor.

Was Kaga part of the group at this time, I thought she was repairing damage from a grounding near Palau?

pacifichistorian said:

It definitely does. To begin with, before going on to the strategic implications, I'd want to know if Somerville lets it go or tries to maintain contact. If I were him, I'd try to, using my Fulmars as snoopers, & try & hit Nagumo again the next night or the night after (as possible).

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That´s tricky. He needs to stay far, far away during the day because of the much superior range of IJN carrier aircraft and I´m quite sure Somerville did not know the actual range. In SEA the Zero´s were anywhere and gave the Allies the impression there were a lot of them, but it was actually the long range that allowed the plane to be in so many different places in such a short time.

Nevertheless, how long would it take Japan to repair a CV that took just one fish? I guess long enough to butterfly a few battles away.

By the way: Unlike in the Naval Battle of Wake, the Battle of the South China Sea saw no night torpedo attacks.

Looking back at the original PoD, if the Japanese sufferred a cataclsymic night defeat it could transform how carrier aviation develops for a decade or more, with much more empasise on radar and directed CAP and less on the alpha strikes.

I think it's a bit much to expect a maximum of 57 swordfish to sink 2 and cripple another 2 carriers at sea at night. But if it did happen it would be a pivotal battle of the war because the Japanese, as we know, couldn't replace their losses in major warships.

However such a loss may shake the Japanese out of their victory disease and stop them from over-reaching themselves, as most major actions have unforseen negative consequences.

PMN1 said:

Was Kaga part of the group at this time, I thought she was repairing damage from a grounding near Palau?

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You're right, Kido Butai had only 5 carriers for the Indian Ocean raid.

Markus said:

That´s tricky. He needs to stay far, far away during the day because of the much superior range of IJN carrier aircraft

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Yeah, I'd overlooked that. (As Murray Walker would say, "If I were Somerville, which of course I am not."...)

Markus said:

By the way: Unlike in the Naval Battle of Wake, the Battle of the South China Sea saw no night torpedo attacks.

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Yeah, I just finished reading that. Fairly epic. Have a look at my fairly epic comments on it.

Riain said:

I think it's a bit much to expect a maximum of 57 swordfish to sink 2 and cripple another 2 carriers at sea at night. But if it did happen it would be a pivotal battle of the war because the Japanese, as we know, couldn't replace their losses in major warships.

However such a loss may shake the Japanese out of their victory disease and stop them from over-reaching themselves, as most major actions have unforseen negative consequences.

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You really can't compare to (USN) massed daylight attacks in OTL Pacific as the FAA tactics focussed on radar directed night attacks with relatively few aircraft. Judging from results in the OTL Mediterranean they could count on quite impressive hitrates - if the target was found (a process in which radar was instrumental). One important factor probably being, that WWII navies had very little with which to defend itself against aircraft attacking at night. If you have the target on your radar, and silhuetted with flares, it is quite comforting for the torpedoplane crew to know that you are unlikely to be hit - and in great contrast to say the Devastor crews at Midway.

Regards

Steffen Redbeard

PMN1 said:

Was Kaga part of the group at this time, I thought she was repairing damage from a grounding near Palau?

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she wasn't, the Japanese only took 5 fleet carriers into the Indian Ocean

oops
someone beat me to the punch

A night attack might have had interesting and potentially damaging results on the Japanese. However, a Japanese counterstroke would have been fatal to the British fleet. Best case for the British is sinking two Japanese CV, but worst case is losing 2 British CV and potentially their escorts.

Given how vulnerable carriers were to a night attack in this era, 57 torpedo bombers could quite possibly hit all the Japanese carriers, although they probably wouldn't all sink. I don't know how good Japanese damage control drills were at this point, but hits which would be survivable when the crew was prepared and awake could easily be fatal in the middle of the night.