By January 1945, the Allies were deeply concerned about a renewed U-boat offensive that might seriously imperil the ground offensive toward Germany from the west. President Roosevelt in his State of the Union address on January 6 had stressed the possibility of a renewed U-boat offensive. Three days later, Roosevelt and Churchill issued a joint communique on the same theme. The media on both sides of the Atlantic had published and broadcast alarmist stories reflecting these dire forecasts.
The lugubrious forecasts were based on faulty or incomplete Allied intelligence and-whether sincere or calculated–on a classic instance of threat inflation. Although the Allied intelligence failure did not appreciably influence the course of the war, as did the failures in the Pearl Harbor attack and Hitler’s December 16 Ardennes offensive (the Battle of the Bulge), it is worth noting.
Some of the factors that led to the intelligence failure were:
- The assumption that on January 1, 1945, there were eighty-seven big Type XXI electro boats fitting out or in workup and another fifty-two under construction, and that by March 1, fifty Type XXIs were to be ready in all respects to launch the new offensive.
This estimate vastly over-credited the ability of the Germans to build, debug. and work up Type XXls in the face of intensified Allied air raids on U-boat yards and bases, the heavy mining of training areas in the Baltic, adverse winter weather and ice in the Baltic, not to mention the widespread chaos throughout besieged Germany. On January 12, American Army troops captured approximately twenty stem sections of Type XXI electro boats at a shipyard in Strasbourg on the upper Rhine River. These stem compartments could not be duplicated or replaced. This heretofore unrecorded capture was therefore as crippling to Type XXI production as were all the Allied air raids and the capture of the Danzig shipyards by Soviet troops. Moreover, Allied intelligence apparently failed altogether to discover promptly that the Type XXIs were crippled by the failures of the engine supercharger scheme, the hydraulic systems, and other defects.
In reality, no Type XXI was anywhere near ready for operations on March 1. Only one-repeat one-Type XXI was far enough along to leave the Baltic in March for further workup in Horten, Norway. That was the show boat U-2511, commanded by Adalbert Schnee, who wore Oak Leaves on his Ritterkreuz, and who had Ritterkreuz holder Gerhard Suhren for his chief engineer. The boat sailed from Kiel on March 18 and arrived in Horten on March 23, at which time Schnee and Suhren requested that experts be sent there to fix the periscope, which oscillated badly, even at the slowest speed. The U-2511 sailed from Bergen on April 18, but diesel-engine defects forced her to return on April 21. She finally resailed on April 30-about which more later.
- A similar miscalculation about the readiness of the duck-size Type XXIII electro boats. On January 1, 1945, Allied intelligence estimated there were forty-three Type XXIIIs fitting out or in workup and eighteen under construction in Kiel and Hamburg and that those yards had a combined production rate of ten boats per month. In reality, the commissioning rate of the Type XXIIIs from June to December 1944 averaged 4.4 boats per month. Less three losses during workup by January 1, there were twenty-eight Type XXIIIs in commission. Only twenty more were to be commissioned by war’s end, a total of fifty-one.
Four small Type XXIII electro boats carried out full war patrols by May 1. The first two, U-2322 and U-2324, each made two patrols of about three weeks duration in the North Sea off the east coast of Scotland and England. The U-2321 and U-2329 each made one patrol to those same areas, the latter a cruise of merely fifteen days. A fifth boat, U-2326, attempted to carry out a patrol but had to abort a luckless cruise of ten days. In total, these five XXIIIs logged 178 patrol days. Altogether they sank five small British freighters for 8,542 tons and damaged the 7,200-ton Norwegian Liberty ship Sverre Helmersoll and the British destroyer escort Redmill.
The Type XXIII electro boats also had numerous drawbacks and faults. The most severe drawback was their tiny size: 114 feet long, about 234 tons displacement. They were smaller even than the prewar and wartime Type II ducks. The XXIIIs had only two torpedo tubes-both forward-and no space for torpedo reloads, compared with three tubes forward and three reloads in the Type II ducks. The XXIIIs were so delicately balanced that after firing even one of the two torpedoes, they had a tendency to broach. The telescopic snorts on the XXIIIs, which were raised and lowered by a compressed-air system similar to that on the Type XXIs, were unreliable.
In sum, the Type XXIII electro boats were little better than useless. Their chief contribution to the German war effort was to confuse many in the Allied camp into thinking that they were more or less the equivalent of the larger Type XXI electro boats.
- A consistent tendency, even by some Allied submarine experts, to overvalue the snort and to underrate the severe immobility it imposed on the U-boat, and the snort failure rate of that era.
Contrary to a widespread view in the Allied camp, U-boats did not snort continuously on diesel engines at speeds of 6 to 10 knots, making good 150 to 250 sea miles a day fully submerged. As related, they snorted at about 5 knots for only about four hours in twenty-four and they were lucky to make fifty or sixty miles a day. Therefore, it took a snort boat nearly eight weeks of a nine-week patrol to reach the English Channel from Norway and return, leaving barely one week for operations. Hence significantly larger numbers of snort boats were required to cover the sea areas and do the work that had been done in earlier and easier times by the non-snort-equipped boats. Moreover, there was an acute shortage of upgraded, combat-ready Type VII and Type IX snort boats.
Foremost among the Allied submarine specialists who predicted that a very tough fight versus the new U-boats lay ahead in 1945 was the British admiral commanding Western Approaches, Max Horton. His deep but misplaced concern influenced seniors in the Admiralty to forecast extremely heavy Allied shipping losses in March 1945, perhaps heavier than the spike in the spring of 1943. If and when this occurred, First Sea Lord Andrew B. Cunningham warned the British Chiefs of Staff Committee that land operations on the Continent were bound to be adversely affected.
These overly pessimistic views greatly angered the Admiralty technocrats in charge of the anti-U-boat activities, particularly two senior division chiefs, N. A. Prichard and C. D. Howard-Johnston. They drafted a blistering attack on Max Horton. In part:
At various meetings recently the Commander in Chief, Western Approaches, has made statements to the effect that he considers that we are worse off materially at the present moment, for means of locating and destroying U-boats, than we have been at any time during this war (and, he added on one occasion, “or the last war”).
These statements are, in our opinion, both untrue and misleading, and although the true state of affairs is no doubt appreciated by Their Lordships, we feel that such statements are bound to give a false impression when made in the presence of other senior officers and members of other services who may not be so well informed, and we feel it our duty to submit the true facts as they are known to us ….
Toward April, a few of the big Type XXI electro boats began to sail from Kiel to Norway. As related, the first XXI, U-2511, commanded by Adalbert Schnee, arrived in Norway on March 23 with snort and periscope problems. Schnee also reported that the maximum safe diving depth of U-2511 was 570 feet, about half of her designed depth limit. On April 18, Schnee sailed from Kristiansand, but his diesel engines were not working properly and he aborted and put into Bergen on April 21, after eluding a British submarine. He resailed on May 3, made a practice approach on a British cruiser, withheld fire, and returned to Bergen.
Several other Type XXIs sailed to Norway. Among them was the U-2513, commanded by Erich Topp, who wore a Ritterkreuz with Oak Leaves and Swords. Yet another was the U-2506, commanded by Ritterkreuz holder Horst von Schroeter (from the Drumbeater U-123). On April 19, an as-yet-unidentified British aircraft hit the U-2506 but von Schroeter took her on to Bergen and was there when the war ended. Still another was the U-2529, commanded by Fritz Kallipke, whose earlier Type XXI command, U-2516, had been destroyed by an air raid on Kiel.
British aircraft destroyed or damaged a number of Type XXIs in the Skagerrak and Kattegat en route to Norway. These included the U-2502, commanded by Ritterkreuz holder Heinz Franke, whose earlier XXI command, U-3509, had been abandoned in Bremen. Although damaged by RAF Mosquitos, Franke got the U-2502 to Horten and was there when the war ended. Hans Hornkohl, the former skipper of U-3512, destroyed in an air raid on Hamburg, got his new XXI U-3041 to Horten. Eleven British Beaufighters hit the U-2503, commanded by Karl Jürgen Wächter, in the Kattegat. Rockets and cannons savaged the boat and killed Wächter. Others took charge and ran the boat onto a beach to save themselves. On the same day in the Kattegat, British Typhoon aircraft damaged the U-3030 and sank the U-3032, commanded by twenty-four-year-old Bernhard Luttmann and twenty-two-year-old Horst Slevogt, respectively.
