By August , the Japanese merchant marine was in tatters and unable to support the needs of the civilian economy. Perhaps the Navy hoped to ambush some Japanese navy ships, but the damage to Japanese sea lines of communication was barely studied and never gamed, much less practiced.
A blockade employing surface and submarine forces was supposed to be the culminating phase of War Plan Orange, the strategic plan for the Pacific, but it was never expected to be the opening component of U. Submarine Force readied for unrestricted warfare. This learning was not confined to material fixes and technical improvements.
Yet this became one of the key adaptations that enabled the Silent Service to wreak such havoc upon the Japanese war effort. Ironically, a Navy that dismissed commerce raiding, and invested little intellectual effort in studying it, proved ruthlessly effective at pursuing it.
The interaction between the Naval War College and the fleet served to cycle innovative ideas among theorists, strategists, and operators. A tight process of research, strategic concepts, operational simulations, and exercises linked innovative ideas with the realities of naval warfare.
Rules were established for evaluating performance and effectiveness, and umpires were assigned to regulate the contest and gauge success at these once-a-year evolutions. The exercises, however, had peacetime artificialities that reduced realism and retarded the development of the submarine. Thus, the importance of avoiding detection, either from the air or in approaches, became paramount.
In the run-up to the war, the Asiatic Squadron commander threatened the relief of submarine commanders if their periscopes were even sighted in exercises or drills.
Given the quality of sound detection and sonar technologies of the time, this was a precariously limited tactic of dubious effectiveness. They were capable of 12 knots on the surface and half that when submerged. They would be far in the wake of the fleet during extended operations.
This inadvertently promoted plans to use submarines for more independent operations, which eventually became the mode employed against Japanese commercial shipping in the opening years of the war. In fact, a generation of crews never heard a live torpedo detonated, proving a perfect match for a generation of torpedoes that were never tested. As one Sailor-scholar observed:.
In its place emerged a pandemic of excessive cautiousness, which spread from the operational realm into the psychology of the submarine community. These areas would be a type of diplomatic exclusion zone, ostensibly to support fleet defense during war. Yet there was a gap between what submarines could do and what the emergent plans to conduct unrestricted warfare were calling for. However, the implications of this change were not acted upon at lower levels in the Navy in the brief era before Pearl Harbor.
Doctrine, training, and ample working torpedoes were all lacking. This created the conditions for operational adaptation under fire later. Due to an insufficient number of boats, limited doctrine, and faulty torpedoes, the submarine force could not claim great success.
By the end of , the Pacific Fleet had sent out patrols. Postwar analyses credit these patrols with ships sunk, with a total of , tons of cargo.
This level of achievement was against a Japanese navy that had limited antisubmarine warfare ASW expertise and little in the way of radar. Tasked with the ruthless elimination of Japanese shipping, the Pacific Fleet was not producing results fast enough. Some of this shortfall was the result of faulty weapons, and some was attributed to the cautious doctrine of the interwar era.
But in line with the pre—Pearl Harbor vision of unrestricted warfare, the U. They had not been successful in dealing with Japanese warships in critical battles such as Midway.
At the same time, King was fully engaged with responding to German Kriegsmarine wolf pack tactics, or Rudeltaktik. He was painfully aware how effective they were and was being strongly encouraged by both President Franklin D.
Navy was not generating the same aggregate tonnage results as the German navy, and he may have concluded that emulating the Germans could produce better results. Comparisons between theaters may have driven King to propose the shift, but he may have also detected trends in Japanese ASW that would eventually weaken U. The operational and tactical context facing the submarine force was increasing in complexity.
By , Japanese convoys were becoming larger, more organized, and better protected. The escort command was employing more airplanes and newer techniques for detection and attack.
As Lockwood noted in his memoir, collective action was not unknown to the submarine force. Before the war, experiments had attempted simultaneous attacks by several submarines, but communications between boats were not good enough to ensure safety in peacetime operations.
These tactics were cursorily explored late in but were abandoned due to fears of blue-on-blue incidents and limited communications capabilities. Now, however, conditions were different, radar had been perfected, high-frequency radio phones were installed, and communications were vastly improved. The submarine force would have to investigate new tactics on the fly in the midst of the war. Somewhat ironically, King called for emulating German submarine tactics just as that force was passing the apex of its operational effectiveness.
May was considered the blackest month for the U-boats in the cruel Battle of the Atlantic. As a result, the U. Navy did not employ the same approach as the Germans. U-boat wolf packs in the Kriegsmarine were ad hoc and fluid.
He would thus direct the assembly of the wolf pack and coordinate its attack from long distance. There was no on-scene commander or collective attack. The Atlantic convoys were rather large 30 or more ships , encompassing a relatively wide area. A convergence could bring together as many as a dozen boats swarming around a big convoy but without any on-scene battle management.
They would stalk the merchant shipping and pick off the slowest quarry every time. The Japanese navy did eventually enhance its ASW efforts, employing land-based surveillance, better radars, and more coordination. As the U. This raised the risk that American submarines would be identified and attacked. Concerted action by the submarines could offset these changes in the operating context. Singular attacks would draw all the attention of an escort, ensuring that the U.
In this last phase the wolfpacks often had gaps in their patrol lines because U-boat had been lost and the BdU was not aware of this due the radio silence used by all boats and sometimes sent orders to U-boats that were lost weeks ago. Around such groups were formed during the war, some lasting only some days and others up to a few months.
The number of U-boats in each ranged from to around 20 in the biggest groups. Events on this day What happened on 11 November? Commander file Karl Fleige U - More officers. U-boat of the day U - 10 patrols 33 ships sunk , tons.
U-boat Finder. From the Gallery U at Bremerhaven, Germany. Some fired at long range, outside the perimeter of the escorts, usually with a spread of several torpedoes. Some, particularly Otto Krteschmer headed straight into the center of the convoy, and fired at point blank range, picking off ship by ship as they sailed passed. Whichever tactics employed, the general strategy was to attack by night, and withdraw by day, with continuous attacks lasting several days, as more boats arrived on the scene.
This had devastating effects and attacking in groups easily overwhelmed the escorts. When an escort pursued one U-boat, another would attack at a different location, creating total confusion and chaos. Shooting off star shells the whole time to comfort themselves and each other. Once Wolf Pack operations began in earnest, the U-boats inflicted heavy losses until the allies developed new technology to counter the threat.
Tonnage figures skyrocketed, and soon reached an all time high. One of the most famous Wolf Pack attacks took place between the nights of October 16th to the 19th, Convoy SC7 was repeatedly attacked by a pack of seven boats, sinking 20 ships out of 34 in the convoy. The very next night, convoy HX79 was attacked with further losses of 14 ships, making a total of 34 ships in 48 hours.
Although the idea originated as early as World War One, but many shortcomings prevented the implementation of this tactic. First, U-boats were dispersed far out across the oceans and Germany lacked the powerful radio transmitters needed to communicate with the boats.
Second, there was no governing body which was needed to co-ordinate the attacks.
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