The Battle of the Pacific

During the Second World War, the Imperial Japanese Navy fielded a fairly large and quite capable submarine force, then wasted it via a doctrine which emphasized attacks on naval vessels rather than on merchant shipping. As a result, the IJN's subs accomplished very little during the war.

But what if, following World War One, the IJN had looked at the achievements of Germany's submarine force and come to the conclusion that attacking merchant shipping was the proper role of a submarine? Let's say they devote a bit more of their resources to submarine construction...maybe by building one less battleship of the Yamato class...and adopt a doctrine similar to that of the Germans for the use of their submarines. During the war, Japanese subs prowl the Pacific and Indian Oceans, hunting merchantmen in the Gulf of Aden, in the Malagasy Straits, the approaches to Australia and New Zealand, off the coast of India, and on the western side of the Canal Zone. How does this affect the war?

Some immediate possible effects...

--The Germans don't have to deploy any subs in the Indian Ocean, as Japanese boats will be operating there. This provides a few more subs for the Atlantic War.

--A greater appreciation by the Japanese of the possible impact of submarine warfare on merchant shipping leads Japan to develop effective ASW technology sooner. Greater losses for American submarines, and more supplies get through to Japan and it's island outposts.

--America finds it more difficult to shift men and supplies to the Pacific via the Canal. With what effects? Maybe someone more knowledgable on that aspect of Pacific operations could expound.

--Greater losses to allied shipping going to Britain from India and other eastern ports. This contributes to the German effort in the Atlantic War.

Any other thoughts?
 

Anaxagoras

Banned
Shifts such as these (not depending on any single POD in time) are always a little more tricky to work with. But if something like what you're saying had happened, the results could have been massive.

IIRC, Japanese submarines had the longest operating range of any nation's submarines during WWII, and we know that they could easily operate along the West Coast of the United States and the eastern coast of Africa from the bases they possessed IOTL. The West Coast of the U.S. down to the Panama Canal and the Arabian Sea coming out of the Persian Gulf wold have been good hunting groudns, indeed.

This could have had an especially strong impact immediately after the entry of the United States into the war, since its anti-submarine abilities were slightly above pathetic, as proven by the utter failure to counter Operation Drumbeat. Suppose the enormous success the German U-Boats had on the east coast of the United States had been duplicated on the west coast?
 

mowque

Banned
Very interesting :), but in a macro sense it doesn't really matter. The USA will squash them.
 
They still have the problm there arent the choke points there were in the Atlantic. And even there, the packs missed most of the convoys.
The only real points to stake out in the Pacific are the start/finish ports, its simply too big.

And while the subs have the range, the further out you patrol, the fewer subs you have actually sinking ships - which was why the KM developed the Milch Cow concept. Which died as soon as allied planes started patrolling the areas involved.

The USN had a much easier task, there arent too many routes for the tankers Japan needs, and thanks to the advancing carrier forces the shipping corridoor available gets narrower and narrower as time goes on.
 

Ak-84

Banned
It could definatly change the equation, if the US is not confident about its ability to move men and material.
 

CalBear

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The difficulty with this idea, and it is actually a very good one that is discussed in different aspects many times, is that it requires the IJN to both change its basic philosphy and its strategic planning for the Pacific War.

I won't go into any depth on the IJN's training and belief system, having posted on it many times (to the point that I have no doubt many regulars to the fourm are hearily sick of it) but it was totally offensive and big gun devoted.

What does deserve a little discussion is the IJN Strategic PLANNING for the War in the Pacific. The Japanese plan was to end the war in a violent coup de main that would overwhelm the West, achieve its goals, and produce a defensible perimeterthat the IJ would then defend with land based airpower and naval strike forces. The IJN was well designed for this goal, including their sub force in a strong scouting role.

Commerce raiding is a long term strategy that is designed to choke the enemy. That neither fit into the IJN strategic beliefs or was a realistic goal in engaging the U.S. (a major exporter of virtually all war materials. including Oil in 1941) The Japanese did put boats outside the Pacific approaches to the Canal, and off the West Coast of the U.S.in hopes of potting the occassional U.S. warship or merchant ship, but they were remarkably ineffective in the effort (again, the quality of the IJN sub commanders and their wholesale lack of aggression is a matter for a separate thread) despite a fairly strong effort, especially early in the War with eight boats deployed (I-17 attacked three merchants, scoring one torpedo hit, resulting the target grounding itself; I-19 three attacks one hit, target made port; I-21 two attack one tanker sunk; I-23 two attack with deck gun, one steamer runs aground; I-25 tow attacks, one tanker hit, escapes but runs agound due to rudder damage). The results, as can be seen, pale compared to the Operation Drumbeat where 5 U-boats took 23 targets (including just one sinking by the U-125, a result that greatly displeased Donitz but equally the TOTAL I-Boat sinking). It must be noted that the shipping traffic off the West Coast was not as thick as on the Eastern Seaboard, but even taking that into account the IJN peformance can only be described as dreadful. Patrols into the Indian Ocean were also made, but results were overall no better, despite the exceptional quality of the IJN Type 95 torpedo.

Lastly, a quick point about the Japanese taking a lesson from WW I. The Japanese learned virtually NOTHING from the European portion of the Great War. This was very clear in the attitude and tactical actions of the IJA, but the IJN was equally unwilling to leard from the Atlantic experience.
 
"America finds it more difficult to shift men and supplies to the Pacific via the Canal."

Not that much more difficult, because it will be pretty easy to patrol and keep the area clean.
 
Also, if you look closely at your effects, you can see why Japan might have emphasized attacks on naval vessels--most of merchant shipping that Japan can attack actually hurts the UK and helps Germany, instead of hurting the US and helping Japan.
 

CalBear

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Hmm. What changes in IJN doctrine would be necessary for the OP's idea to be implemented, and where there any people among the IJN command who could concievably think of such a strategy?

There were very few senior officer who had anything close to the mindset needed to conduct a commerce raiding campaign, as in any organization the ones who are promoted tend to share the same vision as the CEO, and the IJN was intoxicated by Tsushima and something akin to a cult of personality had arisen around the image of Admiral Togo (not much different than that of Nelson in the RN) and his belief in OFFENSE being the watchword of battle.

The changes needed in the IJN doctrine (and the way that commanding officer slots were apportioned) would have been nearly absolute. Submarines were seen as needed to help shape the battlefield for the Decisive Battle, to harrow the enemy as he approached, transmit updates on the enemy's position, and to finish off cripples as he retreated after being defeated. Warships were the target of 1st, 2nd, & 3rd choice, with cargo vessels being nearly beneath contempt (one interesting thing about the IJN submarine attacks off the West Coast and in Hawaiian waters was how many were made with the deck guns, the better to preserve torpedoes for use against worthwhile military targets). This belief was reflected not just in submarine warfare doctrine, but in ASW as well.

It was well into 1944, long after Japan began to be strangled by the American submarine offensive, before even the most basic use of convoys began, and even then the escort was generally a small patrol boat that wasn't nearly as capable as an RN Flower class corvette (not that some of the commanders of these small escorts became serious opponents, thankfully they were not given the resources that the USN or RN spent in the Atlantic). Escort was defensive in nature, almost unworthy of consideration by true warriors and beneath the station of serious warships. The Captain who finally pushed the idea through destroyed his future in the IJN, despite the fact that IT WORKED. Dumb? Hell yes. Very much in alignment with IJN doctrine? Absolutely.

There is also the reality that the IJN codes were throughly broken, to a degree that the wizards at Betchley Park could only dream of achieving. IJN orders were being read in real time and the contents made available to U.S. field commanders almost before it was available to the Japanese addressee. While this was not the case in early 1942, by late in the first war year it was very much the case. When the enemy knows your tactical positioning better than you do, it is a bad sign. Combined with the vastness of the Pacific and large number of destinations that were available it is difficult to imagine a way to conduct a serious Atlantic Ocean style campaign against the U.S.
 
"America finds it more difficult to shift men and supplies to the Pacific via the Canal."

Not that much more difficult, because it will be pretty easy to patrol and keep the area clean.

Well, if the Japanese are stupid enough to maintain a blockade right at the mouth of the canal, sure. But there are many ways to intercept shipping coming out of the Canal that don't require that.
 
Commerce raiding is a long term strategy that is designed to choke the enemy. That neither fit into the IJN strategic beliefs or was a realistic goal in engaging the U.S. (a major exporter of virtually all war materials. including Oil in 1941).

Also, if you look closely at your effects, you can see why Japan might have emphasized attacks on naval vessels--most of merchant shipping that Japan can attack actually hurts the UK and helps Germany, instead of hurting the US and helping Japan.

Even if it is impossible to cripple the USA by means of a submarine blockade because it is a net exporter of almost all major raw materials, the loss of shiploads of those raw materials, outbound to other allied countries, still helps Japan and hurts the U.S. It helps Japan because if the U.K./Commonwealth can be taken out of the war, all of Japan's resources can be turned to face the U.S. Most of the Japanese troops, aircraft, and material tied down fighting the British in Southeast Asia, for example. As for hurting the US, every shipload of outgoing material sunk means money it doesn't collect from the customers who have bought those materials. It also forces the U.S. to build another ship to replace the one sunk, placing more strain on U.S. production capabilities. It also forces the U.S. to tie down substantial naval assets escorting convoys in the Pacific...assets which, historically, were freed to be deployed elsewhere.

You also forget that U.S. armies fighting in the Pacific, China, and South Asia required constant supply shipments from the U.S. to remain in the field. If Japanese commerce raiding can disrupt those sea routes of supply, the U.S. war effort against Japan is in big trouble.
 
Even if it is impossible to cripple the USA by means of a submarine blockade because it is a net exporter of almost all major raw materials, the loss of shiploads of those raw materials, outbound to other allied countries, still helps Japan and hurts the U.S. It helps Japan because if the U.K./Commonwealth can be taken out of the war, all of Japan's resources can be turned to face the U.S. Most of the Japanese troops, aircraft, and material tied down fighting the British in Southeast Asia, for example. As for hurting the US, every shipload of outgoing material sunk means money it doesn't collect from the customers who have bought those materials. It also forces the U.S. to build another ship to replace the one sunk, placing more strain on U.S. production capabilities. It also forces the U.S. to tie down substantial naval assets escorting convoys in the Pacific...assets which, historically, were freed to be deployed elsewhere.

You also forget that U.S. armies fighting in the Pacific, China, and South Asia required constant supply shipments from the U.S. to remain in the field. If Japanese commerce raiding can disrupt those sea routes of supply, the U.S. war effort against Japan is in big trouble.

There is still the problem, as CalBear explained, of the IJN modifying their strategy, and whether they even have enough resources themselves to pull of a U-boat style campaign. Remember, the US is big, and has a lot of capacity for ships.
 
The island hopping campaign required the storing of equipment on ships, like floating warehouses. These were some of the vulnerabilities the Japanese submarines could have exploited.

The one tactic that really proved devastating was the naval mine ambush. This turned out to be the most cost effective way of sinking ships in WWII. It was so successful that USN classified the results for decades. They would use submarines and aircraft to lay mines near enemy harbors where they didn't expect mines. The result was something around one ship sunk or damaged per 30 mines laid. Sometimes results were much better. One Japanese held island was closed by mines for months on end. It turned out submarines were more effectively used laying mines than firing torpedoes. They sank impressive amounts of tonnage for little cost and risk.
 

CalBear

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The island hopping campaign required the storing of equipment on ships, like floating warehouses. These were some of the vulnerabilities the Japanese submarines could have exploited.

The one tactic that really proved devastating was the naval mine ambush. This turned out to be the most cost effective way of sinking ships in WWII. It was so successful that USN classified the results for decades. They would use submarines and aircraft to lay mines near enemy harbors where they didn't expect mines. The result was something around one ship sunk or damaged per 30 mines laid. Sometimes results were much better. One Japanese held island was closed by mines for months on end. It turned out submarines were more effectively used laying mines than firing torpedoes. They sank impressive amounts of tonnage for little cost and risk.

There were MANY ways that a properly utilized IJN I-boat force could have made the U.S. Pacific War more difficult. That has never really been, AFAIK, disputed. The question has always been what could allow the IJN to use the subs in a more effective manner. The answers there as manifold, and difficult to list quickly, but they include:

Institutional belief systems taught to officers from day one of training
Tactics
Strategic Goals
Estimation of the length of the war to be fought
Submarine Officer training
Selection processes for submarine commanders
Seniority and its impact on the IJN decision making process

That is a lot to change. Is is even more of a lot to change when you appear to be WINNING the war.
 
Well, it would mean a few more Civil Air Patrol Squadrons in the Pacific and a greater role for naval aircraft and Coast Guard vessels off the West Coast. Potentially, you could see more incidents like the LA Air raid panic...
 
However its not that likely that the IJN could seriously interdict UK shipping, because at that point in time there wasnt that much they could get at.

Ironically, the really good choke point was Malacca..which they'd already got when they got Singapore.
What else could they go for? There is Indian coatal trade, but thats all small inshore ships.
There is the export trade from Oz, across the Indian ocean, but its a BIG ocean with no major trade runs like the Atlantic. The Ox trade across the Pacific is even worse...sitting off the main Oz ports would be the best option.
and in any case, this could all be handled from America, it would be annoying but hardly fatal.

CalBears points on the philosophy of the IJN is perfectly correct, however even if this was magically changed, there is still a huge problem doing anything like as effective a campaign as the U-boats.

First, there is FAR more Atlantic shipping than in the Pacific, and it gets even worse if you count the shipping per square mile...
For WW2 subs, the big, overriding issue was FINDING your target... They had to be quite close to either see of hear a convoy.
Look at the sinkings in the Atlantic. The 2 big groups are the SW approaches, and the US East coast - both choke points. (its even clearer when you look at a plot of where the kills were in the first 3 years, they all congregate around certain areas, and some destinations). Its choke points that are the key to a successful sub campaign, let the targets come to you where you have a high chance of spotting them. If you have to go faffing about all over the ocean, you dilute your kills, often to a level that makes the campain fail.

Once the allies closed off the easy high-density areas of shipping, the U-boat campaign got a lot harder. The idea of the U-boat patrol line helped (yet again, the issue is finding the ships....), but this left them open to countermeasures, detection, HFDF, and so on.
 
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