one key of possible victory of Japan

The different with german tactics about submarine war is that for japan military autorities was dishonourable attack cargo boats because unarmed!
After Pearl Harbour Japan Submarines Command said has opinion that japanese submarines had to attack cargo boats as primary obiective !
What if Imperial Navy Command was agree with Japan Submarines Command after long meeting?

(English for me is a continue exercise ! )

Irrelevant. Unlike Japan, the US at this time was largely economically self sufficient. To attack American cargo ships would just be a minor nuisance.

hans said:

The different with german tactics about submarine war is that for japan military autorities was dishonourable attack cargo boats because unarmed! After Pearl Harbour Japan Submarines Command said has opinion that japanese submarines had to attack cargo boats as primary obiective ! What if Imperial Navy Command was agree with Japan Submarines Command after long meeting?

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Hans,

During the war, the IJN did send subs to the bustling US west coast where they wrote 'no contacts' in their log books day after day. The 'only warships' mindset infected the IJN submarine arm from the admirals at the top to the deck scrubbers at the bottom.

As for a commerce rading campaign, it may have helped the Japanese a little., but only a little. Unlike the KM in the Atlantic, several factors were working against the IJN in the Pacific. The IJN had fewer boats than the KM, the area they needed to cover was much, much larger, and their larger boats weren't really well suited to a commerce raiding role.

The US did allocate significant ASW assets to the Pacific. The lack of a concerted IJN effort against Allied commerce meant that those assets could be shifted from where they weren't needed' such as between Pearl and the West Coast, and concentrated where they were needed; in and around fleets and invasion forces.

For a Japanese commerce raiding campaign to even approach the level of success Germany's did, the Japanese would have to build many more submarines and re-think the use of those submarines from top to bottom. That would entail a radical shift in Japanese pre-war planning. With a few exceptions, the entire IJN was built with one plan in mind - to first heavily attrit the USN has it moved westward across the Pacific and then defeat the USN in one big battle.

(English for me is a continue exercise ! )

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There is no need to apologize. Your English is good enough to get your points across. In fact, your English is far better than any second language I have!


Bill

Prunesquallor said:

Irrelevant. Unlike Japan, the US at this time was largely economically self sufficient. To attack American cargo ships would just be a minor nuisance.

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It would play havoc with supplying US efforts in the Pacific, which could cause defeats due to insufficient food, fuel, ammunition, etc and prolong the war.

I agree with Matt Quinn that IJN subs may have severely impacted the US resupply efforts. Furthermore, what about supplies being shipped to Hawaii from the mainland? Did Honolulu have the resources needed to repair the US fleet after Pearl Harbor? Ouch.

What about sending some subs into the Panama canal approaches?

A further POD to change the Pacific war is to improve the ASW skills and emphasis of the IJN. Actually, ASW was never considered to be important in OTL.

Even if the US is to win in the long run (likely), the victory will be much more expensive and bloodier.

I think the point here is that there is a major difference between submarine attacks on necessary trade routes and submarine attacks on fleet support. Countries dependant on sea trade (eg Britain and Japan) are vulnerable because we're talking about huge amounts of material moved in predictable patterns. But enormous though it may seem, supplies to armed forces are far smaller, less predictable (you can move a fleet, not a country), and more easily guarded. And if I remember correctly, yes full use was made of repair facilities in Hawaii.