Submarine warfare is one of the three pillars of modern naval warfare. During the course of the pacific war , the US submarines played a crucial role by sending countless Japanese Merchant ships to the bottom. Japanese submarines on the other hand preyed on warships and they successfully torpedoed 2 Aircraft carriers and several other ships, a strategy which in the long run proved to be costly for them in the end. If the Japanese and the Germans had better coordination among them, would the use of German U-Boats in the pacific theater cause any significant impact. We have to also take into account that there was a point in time that the USS Enterprise was the sole standing Carrier of the US fleet and that by destroying it the outcome in the pacific would have changed.
I think there was a certain point in the Battle of the Atlantic, when the U-Boats became very less effective, that it may have made sense to change the theater of operations for them. But, I'm skeptical that even had the Germans had the foresight to know the exact point when their U-Boats became less effective in the Atlantic, that the resources would have been available to effect a change of theater, and even were the resources in place, that the overall impact would have done anything more than a short prolonging of the war in the Pacific.
IF while ENTERPRISE was the sole US aircraft carrier in theater (which is a totally different proposition from "the sole standing Carrier of the US fleet" - there were other carriers in the US fleet) had been lost, the outcome of the war in the Pacific would not have changed one bit. MacA would have carried on in the SWPA, the Essex class carriers would have come out as scheduled, the central Pacific campaigns would have gone on, the atomic attacks would have been made, and Japan would have lost the war. Don't get me wrong, I've a lot of affection for CV-6 - she was a handy place for my father to land his F4F after YORKTOWN was knocked out at Midway, no doubt making a difference in his possible outcomes - but to posit that the loss of a single ship would change the outcome of the the Pacific war is just a bit far fetched.
I believe that the Allies' advantages in manpower, production, and strategic resources meant that any redeployment of U-boats would have meant little in the ultimate course of the war. Also, after the ENIGMA code was broken, the utility of all German U-boats anywhere was greatly diminished. Furthermore, the ability of the Germans to keep the U-boats supplied over thousands of miles must be called into question. Unless they would have been supplied by Japan, but Japan's supply lines were already stretched precariously thin over their empire.
By the time the U.S. had only one carrier left, Japan also had only two (empty) carriers left with no available carrier capable air group to man them. So it wasn't really a big deal. It was said that the battle caused the U.S. lost yet another carrier (and down to just 1) in fact cost the Japanese the war, because it was the last chance for Japan to sink all American carriers ... but they were only able to sink one and damaged the other, in process they lost all the pilots and aircraft on their own carriers. Submarine warfare was indeed cost effective in the war. If Germans and Japanese had mass produced more submarines, it might have a greater impact on the war. I have heard that although all the oil fields were in the hands of the allies forces, at some point the allies were short on fuel due to the transport ships were being sunk in huge numbers. Yes, submarines might not have too much of a direct impact in each battle, they indeed played a huge role in damage supply line which was crucial for the war effort. If I am not mistaken, at least 1 UK carrier, 2 US carriers, 1 Japanese carrier were sunk by submarines during WWII. Although the opportunity for such scoring was limited. They (the submarines) made their money worth.
It wasn't that they had bad coordination, it's that they were tied down in the Atlantic. The Germans had their own problems, they couldn't afford to help the Japanese when they were also at the loosing end of the war.
Certainly when U boats entered the Indian Ocean they caused losses which the hard pressed units of the Royal Navy had little chance of stopping due to lack of numbers. However, the British did not strip the Atlantic of escort ships to help the Indian Ocean, because the only place the U boats had a chance of winning the war for the axis powers was the Atlantic Ocean! The British stayed strong and powerful in that very area for that very reason. A move to send U boats to the Pacific would have been a similar pointless excercise as the Indian Ocean intervention.
It indefinably would have impacted the navel warfare aspect of the theater. The US boasted the greatest Navel fleet at the time and still do today. If the axis could have produced enough U-boats to usurp the American Navel fleets and cut supply lines going to and from across the Atlantic ocean I don't see the allies coming up with a counter measure in time. I mean, of course the Americans and Brits had Submarines, but the German U-boats dominates them over fire power, speed and most of all, silence. The allies could only throw depth charges into the water and hope that it would hit what they wanted.
Hitler envisioned a grand navy and did not give the u-boats the merits they deserved. Certainly if Donitz had had his way then there would have been many more U-Boats built than actually was. Hitler was more taken by the grand battleships and longed to match the British Navy in this field, even thought the days of the battleships effectiveness were drawing to a close. U-boats operating in the Pacific working for the IJN would have had an impacting blow on the Pacific theatre but America's industrial might would have negated much of the impact over time.
