Of a truly new and revolutionary design, but developed and deployed much too late to influence the outcome of the war, were two other classes of U-boats: Types XXI and XXIII. Both types joined Admiral Dönitz’s arsenal in the fall of 1944. Type XXI was conceived as a replacement for boats of the Type IX design like U-505, whose basic strategic purpose and engineering concepts went directly back to World War I precedents. In many ways a technological marvel, the new boats featured all the characteristics of a true underwater craft: a hydrodynamic hull to offer the least possible resistance when moving through the water; a large and strong hull (displacement over 1,800 tons) for greater diving depths than conventional craft; high underwater speed (better than 17 knots); tremendous endurance to elude convoy escorts courtesy of a huge array of rechargeable batteries and snorkel technology; and the latest target-seeking, individually programmable torpedoes. From the beginning it was conceived that these boats would be constructed at inland locations by sections, which would be transported to a seaside shipyard for final assembly. It was not until late 1944, with Allied land forces already pushing onto German soil from East and West, that Grand Admiral Dönitz gained the almost perfect weapon (still sans radar and similar modern guidance systems) to challenge the enemy’s ubiquitous control of the oceans. Alas, of the 828 Type XXI boats ordered, only 118 were ever commissioned—the first, U-2501, on June 27, 1944, three weeks after D-Day—and none saw combat before the end of hostilities. Not surprisingly, Type XXI boats captured at the end of the war inspired postwar submarine designs on both sides of the Iron Curtain. In America alone, boats from the Guppy class to the Nautilus could hardly deny their kinship to their less fortunate forerunners in Hitler’s arsenal.
The much smaller Type XXIII boats were a mere 250 tons. Mimicking the basic technological features of their larger Type XXI cousins, they were essentially craft of limited range designed for coastal defense. Whereas a total of 378 such boats were at one time on order from shipbuilding facilities in places as far-flung as Hamburg, Monfalcone (Italy), Toulon (France), Linz (Austria) and Nikolaev (Ukraine), wartime realities allowed for only 62 boats to be actually delivered and commissioned. Only three managed to inflict minor losses on the enemy in early 1945 before Germany’s unconditional surrender.
Like the smaller Type II and Type VII designs, Type IX boats were developed in the interwar period. Seven were commissioned in 1938 and 1939 by the time Hitler attacked Poland and World War II got under way. They copied many features of the U-81 class of boats in the Kaiser’s Navy, and further improved thanks to two forerunner prototypes (U-25 and U-26 of Type IA). This group of submarines was not designed for either coastal defense or pitched convoy battles in the North Atlantic, although occasionally individual boats were drawn into convoy actions if they were in the vicinity. Instead, the Type IX class was earmarked for long-distance missions to far-away waters where enemy aerial surveillance was comparatively weak and spotty, the convoy system absent or poorly run, and targets easily picked off. This kind of deployment was also likely to draw Allied warships and planes away from the North Atlantic and ease the job of Germany’s other submarines, whose main mission was to interdict incoming ships and shipments to the British Isles.
Almost by definition Type IX boats prowled as “lone wolves” and not in packs. In most cases U-boat Command assigned to them a general geographical area of operations, but the boats’ skippers enjoyed considerable leeway when it came to working out the specific details of their missions. As a German memorandum of late 1941 clearly states, these boats were to wage war “independently and without restrictions within their assigned areas of operation.”11 All this grew from Dönitz’s idea of Tonnagekrieg, the notion that it did not really matter when, where, or how you sank enemy merchant shipping as long as Allied losses month after month and year after year outstripped the number and tonnage of new construction delivered by neutral and Allied shipyards. By this reasoning, the Allies would be starved into submission and surrender as a calculable matter of time.
Type IX boats were exclusively built and serviced by three German shipyards, all on the North Sea: the Deschimag AG Weser in Bremen; the Deschimag AG Seebeck downriver in Wesermünde, and the Deutsche Werft AG in Hamburg on the Elbe River, where U-505 was built as a Type IXC boat. A total of 194 such boats in seven different variations were delivered and commissioned before and during the war, with most seeing deployment and combat before the end of hostilities. Those few not lost in action were either decommissioned before the surrender because of irreparable combat damage or old age, or were captured and distributed after May 1945 as booty among the winners of the war. Most of the latter boats, in turn, were quickly scrapped or otherwise used up by the Allies, or simply scuttled as part of “Operation Deadlight.”12 Some saw a few more years of service under new flags before meeting a similar fate. Besides U-505 in Chicago, only one other Type IX boat exists. In 1993, U-534 was raised from a watery grave off Denmark and restored as a museum boat in Birkenhead, England.
Depending on individual features in their seven distinguishable design variations labeled IXA through IXD42, the double-hulled Type IX boats measured some 252 feet in length, 22 feet in width, drew a little over 14 feet of water, and displaced between 1,200 and 1,800 tons when submerged. They carried between 22 and 25 torpedoes (some in special containers outside the hull on the upper deck) that could be launched from six separate tubes, four forward and two aft. A 10.5-cm gun in front of the conning tower on the main deck could take on surface targets, while a 3.7-cm gun and a 2-cm battery were arrayed on platforms on and behind the bridge for moderate protection against enemy aircraft. After 1943, when suitable targets for surface artillery had practically vanished, the 10.5-cm guns were removed and additional 2-cm anti-aircraft weaponry installed on the platform behind the bridge. Every version carried periscopes for scanning the surface, for submerged attacks, and to search the sky for enemy aircraft.
Two 4,400 HP diesels produced a respectable top speed of 18 to 19 knots on the surface, while battery-powered electric motors moved the boat more or less quietly along at speeds of up to 8 knots submerged. The maximum safe diving depth is variously reported between 150 and 200 meters, but some boats survived accidental dives well beyond that mark while others, obviously, did not. An extended range of at least 10,500 nautical miles—up to 31,500 miles for the special Type IXD U-cruisers operating in the Indian Ocean and the Far East—at an economical speed of 10 to 12 knots, permitted Type IX boats to roam the oceans for months at a time. This range could be extended by mid-ocean refueling and reprovisioning from German surface vessels early in the war, or special Type XIV U-tankers later in the conflict. Occasionally, combat boats returning from operational areas transferred surplus fuel, provisions, and unused torpedoes to outbound boats to top off their stores and weapons. Four officers (including the engineer), 15 senior and junior petty officers, and 29 ratings made up the standard Type IX crew strength of 48. Often, however, extended missions included additional personnel, such as a medical officer, cadets-in-training, war correspondents, extra gunners to man the ever-growing array of anti-aircraft artillery, and so-called “confirmands,” or officers slated to command a boat of their own but in need of acquiring practical hands-on experience.
Versions IXA, IXB, IXC and IXC/40 resembled each other in all central features except effective range, which was gradually extended from about 10,500 nautical miles in the early boats to almost 14,000 miles in later variations. This was achieved by adding more fuel capacity in the space between the two hulls. In addition to swapping the largely superfluous deck gun for more anti-aircraft artillery after 1943, most boats also received snorkels at that time, a tube-like device originally invented by the Dutch to pull in fresh air from the surface while expelling noxious diesel fumes. In theory, with relatively good weather snorkels allowed the boats to run their diesels while running at periscope depth. This advantage not only increased speed but made it possible for the boats to recharge their electric ba
tteries without having to fully surface and face the increased possibility of detection. Unfortunately for the crews, snorkel technology was never perfected. The snorkel’s head often cut under the surface (especially in ugly weather), abruptly stopping the flow of fresh air into the boat. The sudden immersion triggered dangerous pressure variations in the boat that often popped eardrums and filled the hull with toxic gases.
Type IXD boats in their variations D1, D2 and D42, and with their amazing range of more than 30,000 nautical miles, were specifically created for operations in the Indian and Pacific oceans. Some doubled as transporters of precious raw materials between Japanese-controlled ports in the Far East and German bases in western France. When the war ended in Europe, U-181, U-195, and U-862, Type IXs all, refused to surrender and were instead taken over by the Japanese and renamed I-501, I-506, and I-502, respectively. Their change of ownership did not prevent them from sharing the fate of their fellow boats that had ended the war under the swastika rather than the Rising Sun.
The numbering system of Type IX boats, and indeed that of all German submarines in World War II, at first glance defies logic and continues to confound anyone except the most knowledgeable of experts or those with a superbly developed memory. Instead of numbering boats in the chronological order in which they were commissioned and joined active service, the German Navy designated its submarines more or less according to the sequence in which construction orders were allocated to individual shipyards. This arrangement led to some confusion, because some boats carrying high numbers had been commissioned (and sometimes sunk) before a boat with a lower number ever hoisted its battle ensign. Thus, a Type IXC boat with a relatively high number like U-505, for example, was commissioned on August 26, 1941, while U-176, of the same class and design, entered service on December 15, 1941, eight days after Pearl Harbor. This hiccup in the numbering sequence occurred because U-505 belonged to the first batch of Type IXC boats allocated to the Deutsche Werft in Hamburg, whereas U-176 belonged to a long series of boats built in Bremen by Deschimag. Other events only served to complicate this situation. As the war wore on, the Navy cancelled a number of construction contracts issued earlier for Type VII and Type IX boats in favor of the more promising Type XXI and XXIII designs. It did so, however, without canceling and reusing the numbers allocated under the original orders. As a result, the few boats of the Type XXI and XXIII classes commissioned in 1944 and 1945 carried designations beginning with U-2501 and U-2321, respectively.
By any measure Type IX boats are one of the most successful submarine designs in history. Called Seekühe (Sea Cows) because of massive saddle tanks in their mid section reminiscent of bulging bovine stomachs, they enjoyed solid sea-going characteristics, more elbow-room and creature comforts for their crews than smaller Type II and VII models, and a longer life expectancy (generally speaking) than German submarines thrown against North Atlantic convoys. Their crews tended to serve together for longer periods of time under commanding officers with considerable experience. It was customary for junior officers trained as watch officers in Type IX boats to eventually move up to captain boats of this class. Oblt.z.S Oskar Kusch, for example, an outstanding watch officer with several remarkably rewarding tours of duty as second and first watch officer in U-103 (Type IXB), took over command of U-154 (Type IXC) in early 1943 at the unusually young age of twenty-four. Sometimes, however, successful skippers of Type VII craft were rewarded with command of the larger model boat. Thus, after impressive service in the Mediterranean as skippers of U-83 and U-81 (Type VIIB and VIIC boats), Kapitänleutnants Hans-Werner Kraus and Fritz Guggenberger received command in 1943 of the Type IXD2 and IXC boats U-199 and U-513, respectively, for operations in South American waters. In some cases officers of the rank of commander and even full captain were placed in charge of boats and given special or unusual assignments, including operations in the Indian Ocean or supply missions to and from Japanese bases in East Asia. Both Hans Ibbeken (U-178) and Kurt Freiwald (U-181), as seasoned Kapitäne zur See, fell into this category when they took their Type IXD2 boats into Asian waters late in the conflict.
Despite its many solid features, Type IX boats suffered from a number of drawbacks. One was their comparatively slow diving speed, a by-product of their mammoth size. It took a Type IX at least 35 seconds to dive (calculated as the time between the order to crash-dive and the time the boat reached periscope depth or better). Boats were utterly defenseless during those precious few moments. Until fully submerged or at a relatively safe depth they were completely vulnerable to enemy aircraft dropping bombs and depth charges. By 1943 some Allied planes were equipped with an acoustic homing torpedo that could be released into the wake of a diving (and unsuspecting) U-boat. The Mk 24, known as “Fido” by the Allies, followed the boat into the depths where it often rendered the plunge a permanent one rather than merely a temporary evasive maneuver.
Another factor limiting the effectiveness of German submarines of every classification was their nearly complete reliance upon visual means to locate suitable targets. Because they usually operated far from the somewhat predictable convoy routes and movements, encounters between Type IX boats and Allied merchantmen were almost always a matter of chance and luck—or misfortune, if you happened to be the victim. At no time during the war did the German Luftwaffe supply Dönitz’s U-boat Command with sustained reliable information about the location of enemy vessels, nor did the Kriegsmarine’s radio intelligence service fill this void with radio intercepts or high-frequency direction finding feats that could in any sense rival what the Allies managed to accomplish in this field. In short, the U-boats were essentially limited in their hunts to information derived from the lookouts scanning the horizons from the low conning towers of their boats, unstable and pitching platforms as they usually were in the ocean swell, the range of their binoculars even under ideal meteorological conditions restricted to perhaps ten miles in every direction and the airspace above. Underwater listening devices, such as hydrophones, turned out to be highly unreliable and only worked over a limited range, as did underwater telephony as a means of communicating with other submarines in the vicinity.
Submarines were also highly susceptible to depth charge damage. While their pressure hulls rarely cracked under the impact of these explosive canisters, the interior of the boats suffered heavily from the shockwaves. By 1944, the U-Boat Construction Bureau seriously considered installing additional shock-absorbing devices such as rubber and steel springs in the hope these alterations would limit combat damage inside the hull.13
Because of these frustrating conditions the Germans turned to a number of improvised techniques and devices to improve their chances of harming the enemy while reducing their own vulnerability. While German submarines had no active radar of their own, many carried a passive receiver called METOX. If properly tuned, it could in some cases detect whether enemy warships in the vicinity but beyond visual range were emitting radar beams. In theory a useful contraption, METOX became more or less useless when the Allies switched to higher radar frequencies. The receiver not only could not detect these shorter wavelengths, but produced dangerous emissions itself. Each time the boat surfaced the unwieldy reception antenna had to be carried up to boat’s bridge, where cables connected it to the receiver in the radio room below. This time-consuming setup posed a hazard when the boat had to crash-dive, and the antenna was sometimes simply tossed overboard in the interest of saving the boat. At least one Type IX boat, U-126, appears to have been lost in an emergency dive when the conning tower hatch could not be completely closed because someone forgot to cut the METOX antenna cable in time.14
Yet another improvisation available by 1943 was a one-man mini-helicopter or gyro kite. The Fa 330 (also called Bachstelze after a popular, long-legged bird) could be assembled in less than three minutes and launched from the stern of a Type IX. Because it did not have an engine of its own, the reconnaissance craft was towed on a long steel cable. Depending on the boat’s speed and wind ve
locity, it could reach an altitude of 700 feet. At this height maximum visibility increased to more than 30 miles—almost three times the distance enjoyed from conning tower level. Most Fa 330 launches, however, achieved altitudes closer to 500 feet with visibility in clear weather stretching up to 25 miles. As was often the case, however, practical performance lagged woefully behind theoretical expectations. The Bachstelze showed up prominently on enemy radar, which severely restricted its effective use. Because no submarine skipper was eager or likely to risk a surprise attack by surface units or aircraft while trailing the unwieldy device, deployments were limited to waters far distant from concentrations of Allied shipping, such as the South Atlantic and the Indian Ocean. Actual use in frontline situations appears to have been minimal. According to surviving war diaries only two boats, U-177 and U-861, actually launched the Fa 330. Both were in the waters near Madagascar. Only one Allied ship came to grief as a result of these flights.15
Type IX boats participated in World War II from their first deployment into the Atlantic in August 1939 in anticipation of Hitler’s attack on Poland, until the last of them, by then flying the Japanese flag, surrendered to the Allies in the Far East after VJ Day. Type IXs accounted for less than one-third of the Type VII boats that saw action, but are credited with 37 percent of the enemy tonnage sunk by German submarines. Nine of the ten most successful patrols undertaken between 1939 and 1945 were carried out by Type IX boats, and eight of the ten most successful boats overall were Seekühe. In the final analysis, these accomplishments had less to do with the experience or bravery of the boats’ commanders and crews than with the fact they found and disposed of their victims under less dangerous circumstances than those experienced by Type VII boats, which were often forced to carve their prey out of heavily guarded convoys.
Hunt and Kill Page 4