Kriegsmarine minisubmarines

This article deals with the desperate resistance waged by the Kriegsmarine starting in 1944, when its large ships were reduced to scrap metal by decision of Adolf Hitler and others sunk by the navy and aviation. ally Its field of operations was restricted to northern Europe and some rivers.

Dwarf submarines

The story of the German mini-submarines (Kleinkampfmittel) was another desperate attempt to reverse the planned end of the war. While other nations, such as Great Britain and Italy, had resounding successes in special operations using this type of submarine, Germany was unable to achieve similar results.

From the summer of 1944 until the end of the war, these small boats were a kind of last line of defense on the coast and had to fight against powerful allied anti-submarine forces, as well as against the advances of the invasion forces in the French coast. Although the first units were unable to submerge, the later ones proved to be quite developed, although none of them were perfect. Only the Seehunde proved to be operational, but by the time it was used, the spring of 1945, it was too late to reverse any results against the Allies.

Despite the large number of designs that were made and the prototypes that were built, none really demonstrated operability. Minisubmarines of the following types were built:

• Neger: crewed torpedo.
• Marder: crewed torpedo.
• Molch: the first real mini-submarine of the "Kriegsmarine".
• Hecht: minisubmarine.
• Biber: minisubmarine monoplaza.
• Seehund: minisubmarine.

Mini submarine Neger

The Neger was a mini-submarine that had a length of 7 m and a diameter of 0.53 m. It carried a 1x53.3 cm external torpedo (G7e), it had an electric battery of 12 HP, which propelled it at a speed of 4-6 knots, with a range of 18 to 20 miles, depending on sea conditions. where it operated.

The Neger (in black German) was the first German attempt to mass-build the mini-submarine that was called Kleinkampfmittel. It was a simple solution that the German sailors adopted, without having to go through the procedures of designing and drawing project plans. The solution was to mount two G7e torpedoes, one on top of the other; The explosive warhead was removed from the upper torpedo and in its place a transparent dome and the cabin of the only crew member who could fit in it were installed.

Marder minisubmarine

The Marder was a mini-submarine that had a length of 8.30 m, a diameter of 0.53 m and a diving depth of 10 m. It carried a 1x53.3 cm external torpedo (G7e), it had an electric battery of 12 HP, which propelled it at a speed of 4-6 knots, with a range of 18 to 20 miles, depending on sea conditions. where it operated.

Because the mini-submarine Neger was very vulnerable, an improved and submersible version was designed: the Marder. In appearance they were the same, but the Marder was submersible, which made it easier to approach targets and release its torpedo. Although this was an advantage over the Neger, the truth is that this version was more complicated than the previous one for two reasons: first, the operation of the Marder required the operator's full attention, since the diving maneuvers and releasing the torpedo They were very complicated, and second, the small ship had to surface to attack its target, given that it did not have a periscope or any submerged attack instrument.

The Marder was a complete failure in the Mediterranean against United States ships in the Gulf of Saint Tropez, where several of these ships sank during the attack. As a result of the failures of these mini-submarines, it was proposed to take them near Allied ports aboard a Type VII submarine ("U-997"), but the project was cancelled. due to technical problems. About 300 units of Marder type mini-submarines were built.

Molch mini-submarine

The Molch was a mini-submarine that had a length of 10.73 m, a diameter of 1.16 m and a diving depth of 40 m. It carried two external 1x53.3 cm torpedoes (G7e), it had an electric battery with 13 HP of power, which propelled it at a speed of 4.3 knots on the surface and 5.0 knots submerged, with a range of 50 miles at 3.3 knots on the surface and 50 miles at 5 knots submerged.

The Molch (German for salamander) was the first mini-submarine of the "Kriegsmarine". Based on torpedo technology, it is built as a large single-seat torpedo, and can carry two G7e torpedoes. The first of the 363 Molchs was delivered on June 12, 1944, and it soon became clear that its extremely complicated immersion system made it difficult to control during combat. A first fleet of 60 Molchs was used in the autumn of 1944 in Italy and a second in Holland in December 1944. For the third and fourth raking operations it was used again in Holland and Norway, with those responsible realizing the failures that I had this model. Since the Molch achieved no success in combat, she was relegated to a training ship for the crews of more advanced mini-submarines.

Hecht minisubmarine

The Hecht was a mini-submarine that had a length of 10.39 m, a diameter of 1.30 m and a diving depth of 50 m. It carried an external 1x53.3 cm torpedo (G7e) or a mine. It had an electric battery (AV 76 AEG) with 12 HP of power, which propelled it at a speed of 5.7 knots on the surface and 6.0 knots submerged, with a range of 79 miles at 3 knots submerged.

The mini-submarine Hecht (German for pike) was the result of the "Kriegsmarine" of having a mini-submarine capable of attacking moving targets with a torpedo or a land mine. In practice, the Hecht had very poor maneuverability in combat and was soon used for crew training. It was redesigned, adding an additional battery to give it greater autonomy; The last Hechts were built to this design and were used only for instruction.

Biber mini-submarine

The Biber was a mini-submarine that had a length of 9.03 m, a diameter of 1.57 m and a diving depth of 20 m. It carried two external 1x53.3 cm torpedoes (G7e) that were launched by compressed air. It had a 6-cylinder Opel engine with gasoline engineering with a power of 32 HP and an electric battery with 13.3 HP of power, which propelled it at a speed of 6.5 knots on the surface and 5.3 knots submerged., with a range of 100 miles at 6.5 knots on the surface and 8.5 miles at 5.3 knots submerged.

The Biber (German for beaver) was one of the minisubmarines most used by the "Kriegsmarine" during world war II. It began operating in March 1944 and was used extensively in different theaters of operations, with marginal success, despite the high number of units that were built (324). They were replaced by the Seehunde mini-submarines in February 1945.

The Biber mini-submarine was one of Hitler's forgotten weapons. They were one-man minisubmarines that were designed to repel the naval actions of D-Day. Production of the 300 units began in 1944. They began operations on June 6, 1944 and, according to some authors, could have changed the course of the war.

The Biber was conceived shortly before the Normandy Landings and in just eight weeks the design plans were made; It was built with 3 millimeter thick steel plates, in three sections that were assembled in watertight compartments. The main compartment, located between the first and third compartments, housed the operator and contained a turret. Behind the operator was the Opel gasoline engine that the boat used when sailing on the surface and the electric motor that it used submerged.

When the Allied invasion of Normandy took place, they launched themselves against the invasion fleet; between 60-70% were destroyed on that occasion, some due to the effect of the allied anti-submarine forces and others due to the effect of CO2, produced by its engines, which poisoned its crew member who was killed. Their operations on the Dutch rivers and canals proved most successful when they operated against bridges. Due to this, it was planned to use them in Norway, in the Murmansk area, transporting them by conventional submarines, but this operation had to be canceled due to insurmountable technical problems. The same happened with a secret operation to transport them to the Suez Canal in BV-222 seaplanes.

Seehund mini-submarine

The Seehunde (German for seal) was a mini-submarine that had a length of 11.86 m, a diameter of 1.28 m and a diving depth of 30 m. She carried two external 1x53.3 centimeter torpedoes (G7e). It was powered by a 6-cylinder Büssing engine with diesel engineering with a power of 60 HP and by a 25 hp electric battery, which propelled it at a speed of 7.7 knots on the surface and 6 knots submerged, having a autonomy of 207 miles at 7.7 knots on the surface and 63 miles at 3 knots submerged.

All the minisubmarines prior to the Seehund did not obtain the expected results, because they were built very quickly and without a design and in-depth studies of their characteristics and performance. When this point became clear, German naval engineers set about searching for a mini-submarine, based on traditional U-Boat technology, resulting in the Seehunde. The first of the 285 Seehunds was completed in September 1944, and entered mass service in 1945, proving superior to all previous models, with 1,000 units of this model being ordered.

Used against Allied supply in the Schelde-Themse area, 70% of the Seehund operations had contact with the adversary and 90% of them survived the mission. The results of their missions showed the balance of nine cargo ships sunk and three more damaged and the destruction of the French destroyer "La Combattante". Today a Seehund survives, which is exhibited in the German Museum in Munich.

From this model, the Spanish project known as the Foca class was derived.

History

Development of the Neger

One night in the first days of July 1944 on a beach west of Trouville, shortly before deserted and abandoned, it is filled with Germans who maneuver a series of tubes to take them to the sea. Other men enter one of the tubes and are locked in by securing a plexiglass cover with screws. These torpedoes are not launched from a destroyer or a submarine, but by a person who takes them to a very short distance from their target and releases them: the upper tube, which houses the lone man who crews it, is actually an impeller to carry the real torpedo at the bottom. The aiming element of this curious device consists of a sight drawn on the plexiglass and a guide formed by a metal rod welded to the bow of the device.

The difficulties for its use are numerous: there must not be much wind, it must be used during clear nights, since its crew member is only 0.50 m from the surface of the water. On June 29, 1944, Major Admiral Karl Dönitz announced to Hitler the beginning of the “Neger” operations in the landing area. He also announces that the explosive boats will soon intervene and does not omit any detail to clarify that their use is subordinated to the state of the sea.

Hitler, totally deluded, dreams of destroying six to seven battleships with these small boats and orders Admiral Dönitz for the Kriegsmarine to act as in 1940 in Norway against the English convoys. In 1944, with the fleet of large ships dismantled, cannibalized and turned into scrap metal and the submarines sunk, Hitler asks the Kriegsmarine to act as in 1940. In 1944, only single-seat torpedoes, explosive boats and midget submarines Neger, Marder, Hecht, Biber, Molch and Seehunde, names of the different types of midget submarines.

Neger attack technique

The technique adopted by these devices is to navigate for hours, propelled by their electric motor at a speed of 5 knots, to the mouth of the Orne if they do not deviate from their route. Many return exhausted after long hours of fruitless navigation and totally lost and ignorant of where they are. The luckiest discover an almost motionless target; then the pilot of the Neger approaches his target and releases his torpedo. Most of them see long lines of fast ships emerge and pass before them and disappear again. If they detect a suitable target, they approach stealthily, release the lower torpedo and its explosion mechanism is fired seconds later. The compressed air propels it until its own electric motor starts up and propels it towards the target. The pilot waits; He does not know if he has estimated the distances correctly, if the torpedo will not deviate or if the ship will make any maneuver to get rid of the explosive device. If he hits the target, he will return attempting to gain the coast and his base several hours later.

In the first operation, only two single-seat torpedoes were lost. The majority did not manage to reach the objective and those that did reach hit two targets. The operator and leader of the flotilla that sank a cruiser of the Aurora type receive the Iron Cross. The second operation finds the English forewarned, everything that shines in the moonlight is immediately destroyed. In many cases, once the surprise is over, they don't even destroy them, they approach them and lift them up with an operator included. Over time, the losses become exorbitant again: 60% to 80%.

Development of the Biber

In 1940, Lieutenant Bartels had drawn up plans for midget submarines, manned by one man, and built them by his own means in Norway in the spring of that year, proving effective. In 1942 he wrote a report in which it was read that he was of the opinion of defending the German coast with “special weapons”; something unthinkable in the High Command, since at that time Germany was winning the Battle of the Atlantic. When the situation changed radically, in the fall of 1943, they were built. It was necessary to quickly test, fine-tune and mass-produce weapons capable of stopping the imminent landing of the allies on the European continent. Bartels, then a lieutenant commander, was summoned. Based on his plans, the first single-seat German midget submarine of the Biber type was built at the Frenderwerft shipyard in Lübeck. This device disappointed everyone, since in the first test it sank.

At the time of disembarkation there was not a single Biber floating; For four weeks only the Negers operated, without achieving any notable success. In a small isolated forest lost in the solitude of Lübeck, the volunteers came across a new weapon, the Biber. Training began immediately. Vice-Admiral Heye, appointed chief of the assault engines, did not hide the fact that it would be extremely difficult to put these tiny weapons into action. In mid-August the first 20 Biber set off towards the English Channel. On the night of August 29, the 18th set sail. The Biber had to fight against the wind and heavy seas. Two transports were sunk, one of which was an 8,000-ton Liberty ship. Afterwards, it was necessary to evacuate Fécamp. The collapse of the German resistance in France forced the Biber to retreat, while other Biber arrived at the Blaukoppel.

Biber Attack

In November 1944, a column of huge trucks pulling several trailers covered in waterproof tarpaulins advances towards Rotterdam. Two fleets made up of 60 Biber single-seaters converge towards that city, transported along different roads in small groups. One of them must first carry out a mission in the Waal, one of the mouths of the Rhine.

When the German advance on Holland took place in 1940, the paratroopers seized two bridges over the river in Nijmegen, without the Dutch being able to blow them up. In 1944, the situation was reversed. The Americans defend the bridge so vigorously, without the Luftwaffe being able to defeat them. Then the mission is entrusted to the navy. The navy divers manage to blow up the railroad bridge, but not the highway bridge. The Americans increase their precautions, since the German front is only 5 km from the Waal, on the eastern shore, and they place four heavy underwater nets. The Biber are tasked with blowing up that bridge. The main task is to first blow up the nets. Bombs are designed with a certain negative buoyancy, and on “D” day, groups of 60 are launched into the river, half an hour apart, several kilometers away. The pumps descend to the river bed, where they are carried by the current. Five minutes later, the first net flies into a thousand pieces, then the second and the third.

The Biber launch the attack, camouflaging their periscopes with grasses and reeds, which appear to the Americans as harmless debris carried by the current. They manage to get through and completely destroy the remains of the nets. After carrying out this task, they return to fulfill the main mission: blow up the bridge. While the explosions occur in the distance, the Biber tow two tree trunks, to which explosives have been attached that will be activated by a photoelectric cell, which activates the firing mechanism in the shade. A series of explosions occur; At first the Germans believe they have blown up the bridge. The next day aerial photographs show the bridge intact. The mines had blown up only three of the four nets. The explosions heard had been produced by the fourth network that remained intact during the mine attack. The Biber adventure in this area was a total failure.

After their failed mission in the Waal, the Biber are sent to Rotterdam to act against enemy supplies. In the last weeks of 1944 they are taken from their shelters about 20 times. The Biber have a length of 8.70 m and a beam of 1.45 m. Only its small turret protrudes from the water, when the operator is on board and in the water.

One night at the end of 1944, the Biber are transported by tugboats to Hellevoestsluis, a river lock located north of the island of Goeree. The lock gates are not opened for more than an hour for the Biber, which are powered by their combustion engines, to pass down the Meuse. Generally the operator carries a wrist compass, a navigation chart and a sheet of paper with the details of the mission, which is given to him moments before departure. The route he must follow is carefully charted by experienced German sailors. With its two torpedoes, the Biber does not develop more than four knots; In some places the current has that speed and the small submarine cannot move forward. There are times when the day lasts several tides. In these cases, it must look for a suitable shelter and wait until the other tide that is favorable: sometimes the day lasts two, three and even four tides, taking advantage of the currents that are favorable to it. Obviously all calculations are theoretical. It is understood, then, that the Biber only attack when conditions are favorable.

But the English have also learned that the Biber attack under favorable conditions. In addition, there is constant aerial surveillance, so the English know when the Biber go to sea. When these favorable conditions arise, supply lines are interrupted and a veritable mass of submarine chasers, minesweepers, frigates and corvettes are unleashed against them. Despite everything, the Biber managed to sink nearly 95,000 tons in the Scheldt, between December 1944 and April 1945. Although some of them fulfilled their mission, they never returned. Losses reach 60% to 70%.

The Biber disaster

In the course of the months of 1945, the Biber suffered two hard blows, in which the English had no participation. The first of them occurred in January of that year in Hellevoetluis. Someone mistakenly activated the torpedo of a Biber, it was mobilized, activated and exploded, giving rise to a large wave that detached the torpedo from another Biber and it exploded again; At the end of the disaster only four or five Biber remain afloat. The others have sunk out of a total of 30 that made up the flotilla. A large ship is on the dock and there are dead and injured everywhere. At first it was believed, in the confusion, that it had been an English air attack. Since this accident, operators have avoided Hellevoetluis, preferring the route that passes through Hoek Van Holland, even though it is longer.

On January 6, 1945, another accident with the same characteristics occurred, but the results were more dramatic, since almost all the operators were already on board their ships. Only those who had left the pond minutes before survived the violence of the explosion. For the second time, the men of the submarines are victims of their own machines.

An analogous incident, with less serious consequences, occurred around this time on the high seas aboard a midget submarine of the Seehunde type. The Seehunde were an extension of the Biber, they were larger and were crewed by two men: a navigation chief and an engineer. These machines were only able to operate during the last months of the war. The Biber displaced 6.25 tons and the Seehunde 15 with their torpedoes. The Kriegsmarine assault units had a total of 324 Biber, 390 single-seat Molche and 250 Seehunde. The base of the latter was in Ijmuiden (Holland).

Seehunde incident

During one of the last operations of the Seehunde, a British destroyer passes the bow of the small German submarine. The English have not noticed the presence of the small ship. The submarine's navigation chief starts the firing mechanism. The submarine then increases speed; When they try to submerge, the controls do not respond. The torpedo is stuck and the elevator is also not responding. The small submarine with its port torpedo already primed, heads in a straight line towards the destroyer. The periscope and turret now protrude from the water, leaving a foamy wake in the sea. The English notice and begin shooting at the unidentified object. The submarine's crew manages to maneuver by loading the rudder to starboard; The destroyer also maneuvers and the torpedo submarine skims the stern of the English ship. This time the German submarine and the English destroyer are saved.

Seehunde Training

During the training stage, the Seehunde carried out - as the crews' first exercise - crossing the English supply lines. The torpedoes were replaced by large food depots. The small submarines left Ijmuiden, crossed the heavily guarded enemy lines of communication submerged, and often entered, after a long journey of several days, Dunkirk, carrying supplies to the garrison of that besieged city.