By Rolf Stibbe
SNA (Santa Barbara) — Much has been written about the application of ‘stealth technology’ in modern warfare, the rendering of a military vehicle virtually invisible to detection by radar systems. The advanced materials have been built into virtually everything, from revolutionary fighter aircraft, pilot-less drones, and warships. If we look back in time, we find that the origins of this unique form of ‘radar camouflage’ has its humble beginnings in Japan in the early 1940s. This author had a rare opportunity to speak with the one of Germany’s leading wartime scientists in the field of radar, infrared, and countermeasures, Dr. Heinz Schlicke, in the mid 1990s, and he shared his knowledge of some of the most secret Axis military projects dealing with stealth technology. In the closing weeks of the war, Dr. Schicke was lead commander of the secret voyage of a German U-boat submarine (U-234) directly to Japan, to transfer advanced military technology to the Japanese. Schicke was assigned directly to the military attache in Tokyo on his arrival. The story of this remarkable voyage to Japan encompasses the advent of modern stealth technology and delves into the realm of atomic energy.
In March 1943, the German U-boat Arm under the command of Admiral Karl Doenitz had brought the Allied convoy system to the verge of collapse. A spirit of optimism prevailed at the OKM, Oberkommando der Marine (Headquarters of German Navy) in Berlin as reports of numerous sinkings were received over the teletype. Doenitz’s U-bootwaffe was engaged in the largest offensive of the North Atlantic against Allied convoys. The results were encouraging. During the first twenty days of March they had sent an estimated 141,000 tons of shipping to the bottom of the Atlantic with the loss of one U-boat. More good news surfaced that the Admiral’s B-dienst intelligence network had again broken the Allied naval codes and read each message with ease.
The excitement was abruptly curtailed on March 18th when Doenitz received word that Allied VLR (Very Long Range) aircraft had penetrated airspace in the eastern mid-Atlantic. Within days the OKM was flooded with communiques from a number of boats returning home with depth charge battle damage. The tide had turned virtually overnight, without warning, as the Admiral began to explore his options. In the months that followed, the U-boat losses soared, forcing Doenitz to recall his remaining U-boats back to their bases on May 24th. The situation deteriorated with each passing day as the puzzled OKM played the role of helpless bystander in the unfolding drama.
Admiral Doenitz met with Adolf Hitler on May 31st and explained the crisis facing his U-boat men. The Admiral believed that the Allies had developed a new aerial search device responsible for the sudden increase in losses. He returned to his headquarters and summoned to his side the top scientists and engineers in Germany. These determined men made a concentrated effort to save their fellow countrymen riding out the struggle in the depths below, with the source of the problem yet to be identified.
Among the ranks of the scientists was Korvetten Kapitaen (Lieutenant Commander) Dr. Heinz Schlicke, who was assigned as group leader for submarine communications in the OKM. He had attended the Institute of Technology in Dresden where he received his doctorate from Professor Heinrich Barkhausen, renowned for his pioneering work in feedback systems. This brilliant man was affectionately called ‘Electron Jesus’ by his students.
With the onset of 1939, Schlicke was employed at Telefunken (still one of the pre-eminent German electronics firms) where he worked mainly with high powered transmitters. Unfortunately, the job wasn’t much of a challenge. His education would not be wasted, as the Second World War unfolded in September with the invasion of Poland.
The ‘Battle of the Brains’ continued as the engineers of the Kriegsmarine, AEG, Telefunken and Siemens pitted their wits against their Allied counterparts in England and the United States. The secret conferences in Berlin began as scheduled, Schlicke among those in attendance. The situation had become critical as the U-boat Arm neared complete collapse: “We were desperate. When Doenitz came to us with these reports of infrared searchlights, we didn’t know what to do! Several of our engineers were even assigned to U-boats to observe these strange red lights. The U-boat diesel engine exhaust was then redirected underwater and crewmen wore special uniforms impregnated with materials to prevent the emission of body heat.”
The Germans analyzed every possible solution to the puzzle. Engineers even performed chemical testing of the U-boat diesel engine oil and found it susceptible to ultraviolet emission.
Schlicke had reported his findings immediately: “Far more important for Anti-Submarine Warfare (ASW) is the location of the U-boat if it leaves an oil trace. If an ultraviolet searchlight is turned on at night on an oil trace, no matter how slight this trace may be, the oil will give off a very strong fluorescence. (Tests made from the bridge across the Great Belt in Denmark gave excellent results). Since this type of search presented a definite danger to U-boats, two parts of a special chemical manufactured by I. G. Farben were added to the diesel oil furnished all boats. This chemical had no effect whatever on either the engines or the qualities of the oil, but yet made it completely impossible to locate an oil trace by ultraviolet light.”
The engineers scored a small technical victory against the Allies. However, their gallant efforts still did not slow the rate of U-boat destruction. Alternative countermeasures had to be discovered and quickly, with the lives of many seaman hanging in precarious balance.
The scientists and engineers attended their next conference in Berlin. Schlicke took his seat as the meeting got underway. “We were gathered to attend these special meetings and discussed possible solutions to the U-boat dilemma. We had submarine commanders, professors, scientists and anyone who had a brain present. Doenitz was a really sharp guy during these terrible times and was really cooking with ideas. We met with him at least once a week. We simply could not detect the new Allied radar because we didn’t have the transmitter vacuum tubes and receivers sensitive enough to detect the higher frequencies. We did have special crystal detectors but they were very primitive. The British had used higher frequencies with shorter wavelengths that our U-Boat METOX unit couldn’t detect. This is why so many U-boats went kaput. Professor Keupfmueller, the head of Siemens Laboratories was also present at the meetings. He reported directly to Doenitz. This man was brilliant and an asset to our team. I remember when he was approached by several professors who proposed constructing U-boats out of glass to which he promptly responded ‘You Idiots! it would splinter into a thousand pieces if it got hit!’ These professors were then thrown out of the meeting immediately. Keupfmueller always came right to the point. Whenever you were given an assignment to find a solution to a problem for the next week and you didn’t have an answer… you were in big trouble.”
The Germans had then begun several elaborate projects to mitigate the losses. Schlicke remarked that a project was in the works which envisioned a U-boat with an antennae buoy, attached to the boat via cable and winch. Although it never came to the prototype stage, it demonstrated the drastic attempts made to save the U-boat crews.
What resulted, however, was a more practical device called Kurier (Courier) which was a small buoy that was shot from the torpedo tube. Upon surfacing an antennae automatically shot out and transmitted a coded message in a fraction of a second after a slight delay, thereby allowing the U-boat to sneak away unnoticed. The buoy later exploded to prevent its discovery.
In August 1943, the mystery was finally solved when a British radar set, recovered and rebuilt from a downed R.A.F. bomber in Rotterdam, Holland revealed its operating characteristics. The ‘Rotterdam Apparatus’ showed that the Germans had fallen dangerously behind the Allies in radar technology. This short wave radar set could detect a U-boat regardless of distance or weather conditions. Most important of all is that Germany had no device to detect its presence. The frantic research efforts continued to build new radar detection devices sensitive to the shorter wavelengths.
The Germans had then embarked into fields of technology dealing with radar camouflage.
Fortunately, work on protecting U-boats from radar had started as early as 1939. They also knew that two Japanese professors who studied in Germany had developed a new material called ‘Ferrite.’ This material was a spectacular new development in the electronics field and the German scientists already had a use for it. Schlicke recollected, “We needed this material desperately to cover the U-Boat’s schnorkel to decrease its radar deflection and increase its absorption. This was the secret Project Schornsteinfegger (chimney sweep). Such materials-manipulation techniques would not become popular until some forty years later, with the unpublicized debut of ‘stealth’ technology incorporated into modern military equipment.
In addition to the revolutionary iron based coating, the Germans developed a radar absorption material of their own. Code named ‘Alberich,’ this 4mm thick double rubber sheet was ideally suited for U-boats and resistant to barnacles. Schlicke was to hand over the data on the material to the Japanese if deemed necessary.
Like the development of the swept back wing of the Messerschmitt Me-262 jet fighter, to rockets, missiles, and splitting the atom, the discovery of a strategic application for advanced technology is an excellent example of the great achievements of the wartime German scientists. The incredible burden of a war beginning to go sour pushed them into areas where none had tread before. It is also worth noting that when the Germans received word of the possible implementation of the ‘Morgenthau Plan,’ an Allied postwar restructuring of Germany into a harmless agricultural nation, they redoubled their efforts and fought to the end to prevent the German collapse.
Another example of German ingenuity was the construction of a new transmitter in Magdeburg. This ELF (Extremely Low Frequency) unit consisted of a central transmitter, coils and many towers laid out in an open field in a circle. Dr. Schlicke recalled that this project, ‘Goliath,’ required at least 60 tons of iron wire. By carefully directing a sharp beam you could change the frequency band of the radio spectrum. It was to be used exclusively for submarine communications. The project was quite extensive and was heavily camouflaged against the prying eyes of Allied aircraft. This long wave technology could have made a dramatic contribution to the joint Axis war effort. “We had tremendous plans of what we going to do in Indonesia with the Japanese,” Schlicke noted.
At any rate, the information on the secret coating now within the German’s grasp would not just entail an exchange of documents. Dr. Schlicke recalled, “The Japanese way of working was that you have to have personal contact with them.” A messenger needed to be found, but who would be able to ‘break the ice’ with the Japanese?
By a stroke of luck, the answer lay in a connection with Schlicke’s old Alma Mater. He explained: “Before the war, Professors Yogoro Kato and Takeshi Tokei of Kyushu University, Yokohama Japan had corresponded with Professor Hans Falkenhagen at the University of Dresden regarding their work on ‘ferrities.’ One of my tasks in Japan was to be the investigation of what progress the Japanese had made in this direction.”
Schlicke became the connecting link the Germans needed. It was then decided that he head an entire technical mission to Japan via U-boat. In addition to his fact-finding, the doctor would also brief the Japanese on the latest German developments in establishing effective countermeasures to Allied radar equipment. He was assigned to the Naval Attache in Tokyo.
Along with the doctor were two Japanese officers, Lieutenant Commander Hideo Tominaga of the Imperial Japanese Navy, a naval architect and submarine designer, and Lieutenant Commander Colonel M. Shoji Genzo, an aircraft construction engineer. Also aboard were two engineers from Messerschmitt Aircraft, Luftwaffe General Ulrich Kessler with staff, and a navy judge advocate, Commander Kai Nieschling.
The first submarine allocated to ship Schlicke’s technical team to the Far East was sunk in the Kattegat off Denmark. A second boat was procured and arrived at Kiel for internal modification prior to its secret voyage. The U-boat selected, the U-234, a monster type XB minelaying vessel of 1760 tons, was well suited for the mission. They were the largest U-boat type constructed by the Kriegsmarine during the war.
There was quite a technical bonanza to be found aboard. Among Schlicke’s own stock, ingeniously labeled ‘Schlicke Toni,’ ‘Toni’ indicating Tokyo, were advanced plastics and raw materials for microwave antennas, components for long-wave transmitters, 100 Leica cameras, a quantity of optical glass, and samples of the latest German work on Ferrites. Enclosed within the hull of the U-234 was also included a disassembled Messerschmitt Me-262 jet fighter, a state of the art Henschel HS 293 Glide Bomb, and the most top-secret item, a shipment of 1,200 pounds of fissionable uranium 235 in gold lined containers.
Dr. Schlicke, at his office in Naval Headquarters at Eberswalde, north of Berlin, readied his documents and equipment in preparation for his trip to Japan. The young doctor then heard that Dresden had just been hit in a massive air raid. His wife, children and parent’s safety became his chief concern. He then made a privileged telephone call from the OKM to Dresden to see if his family and parents had survived the attack. The bombing of Dresden, still controversial among historians even today, occurred on February 15,1945, as the bombs rained down on the ancient city. It has been conservatively estimated that over 135,000 people, many of them refugees from the east, perished in the flaming tornado of the firestorm. Naturally, no one knew the true extent of the raid at the time, so Schlicke took it in stride, hoping that his family’s luck would hold. It certainly wasn’t a good omen.
It was March 23,1945, by the time the U-234 left Kiel, even though U-boat service was akin to a death sentence by that time. The commander of the boat, Kapitaenleutnant (Lieutenant First Class) Heinrich Fehler with his stripped down crew and VIPs set course for Oslo, Norway, for a hull pressure test prior to departing for the Orient. The U-234 began its undersea diving test and three hours later it collided with the U-1305 which was monitoring the dive: “I don’t know who the idiot was who sent that other boat down with us… it sounded like two cars crashing together!”
The U-234 suffered some minor damage to an oil tank. The leaking fluid would have given away the boat’s position quite easily for the enemy, like a shark attracted to a bleeding fish. After being repaired at Kristiansand, the submarine finally departed for Japan on April 15 under the escort of a German subchaser. As the Schlicke recalled, fear of the British anti-submarine units was so profound that the boat rarely exceeded one knot in certain areas of the Atlantic. Above this speed, they felt that the U-boat’s propellers would make too much noise. So departed the U-234, one of the last U-boats to leave Germany before the capitulation.
The next few days found the boat passing near the British Isles and was repeatedly depth-charged. Yet Schlicke and crew endured the explosions, unfortunately losing a good portion of his hearing in his right ear as a direct result. We can only marvel at the stamina of the U-boat crews; the nervous and physical strain of such an ordeal were beyond imagination: “We were attacked quite often and had to dive down to about 660 feet to escape the depth-charges. It was our maximum depth without being crushed. The iron and steel groaned as the outside water pressure increased. We were often forced down deep for many days and didn’t even know if was day or night. In our crew compartment there were numerous dim lights, but few remained lit from the constant attacks. I remembered that we endured more than one hundred depth-charges per hour as our boat rocked back and forth. We always managed to repair the damage, though it wasn’t easy. During our long dives the oxygen supply got low and all work and movement was kept to an absolute minimum. It was not a comfortable feeling when you’re short of oxygen.”
During the numerous depth-charge attacks, Schlicke was able to observe the two Japanese officers aboard, and remarked, “The Japanese were fantastic and didn’t even flinch one bit with each explosion. They were so stoical and didn’t even say one word. I still have a very high regard for these men.”
When the crew wasn’t being depth-charged, or running from stem to stern to steady the boat while snorkeling in heavy seas, some of the German officers took turns playing chess with the Japanese.
The thing that really struck me about these men was when we played chess with them. If the Japanese lost, they were so upset since they couldn’t stand being beaten by a westerner. They were extremely nationalistic and could not bear the thought of losing. Beat them at chess and they wouldn’t eat for days. I admired them and they were fantastic guys.”
The agonizingly slow voyage continued. Schlicke went on the tower one day and meticulously set up a special radar warning device, based upon the latest Allied frequencies. His special project, truly the cutting edge in German radar technology, was smashed to bits by the first wave it encountered. The rough seas continued as the U-234 struggled onward towards Japan.
The high waves of the North Atlantic could also inflict terrible pain on the entire crew as well. At snorkeling depth, the U-boats would utilize their diesel engines to recharge the batteries. When a large wave would close the protective valve in the snorkel air intake, the diesel engines would then be acting like a huge vacuum pump, drawing the air out of the boat and expelling it as exhaust gas. The resulting pressure drop was enough to pop the corks out of little perfume bottles that each crewman carried for washing. It was incomparably worse than what one might experience during a descent in a modern airliner, with ears unable to be cleared of the increase in pressure.
Dazed and disoriented, due to the poor air quality, weakened by the tasteless food (meat and potatoes having long since rotted away in the humid air), the U-234 surfaced and received Admiral Karl Doenitz’s message regarding Germany’s capitulation: “One day when it was quiet upstairs, we surfaced and found out that our antennae was missing. An emergency antennae was then setup and we received the following message:
The war is over. Surrender and do not destroy any equipment. By your actions we will save the lives of millions of Germans trapped in the east. Doenitz.
We all then thought that the war will continue against the communists. I was then relieved by the communique since I didn’t have to kill myself when faced with capture.”
Even though the war was declared over for the Germans, the crew of the U-234 faced danger from a new quarter. Japan was still at war and surrender for the two Japanese officers aboard was totally unacceptable. Schlicke described the dangerous and delicate situation, requiring great diplomacy: “When our U-boat left Germany in April, we were all ordered to kill ourselves when faced with capture. So, now we didn’t and the Japanese went wild! They wanted to sink our boat! This was actually very easy to do since we were deep underwater and by merely opening the wrong valve could cause the water to come shooting in like liquid steel which was of course extremely dangerous. These Japanese had been trained in submarines and we figured that they’d try something. We then placed them under armed guard to prevent any sabotage… even when they went to use the toilet. One day when I returned from my watch outside, and a crewman suddenly approached me and said, ‘Captain! the Japanese won’t wake up!’ I then followed him to the bunks where they slept. I gently shook them from behind the curtain and there was no response. After moving the curtain aside, I saw both men hugging each other and covered with foam. They had overdosed on Luminal sleeping tablets and committed suicide.”
The two dead Japanese officers were given a solemn, burial at sea according to naval tradition. With the bodies, all their diplomatic bags, and documents were also thrown overboard.
Now began serious discussion on a plan of action. Doenitz’s order to surrender was accepted as fact, but how should they surrender? One of the VIPs claimed to know President Roosevelt personally. When reminded that FDR was dead and Harry S. Truman was now in office, he scaled down his claim to say that he knew some people in a high office in the US government. ‘I will swim ashore and make contact with these people, so we maybe get a good reception’, he said.
The idea was considered ridiculous by Schlicke and his colleagues. He then devised a plan of his own which he put forward to the crew: ‘We have enough weapons that we can run a little island somewhere, somehow…,” which was true. In addition to the U-234 armament, they had pistols, MGs, Panzerfaust anti-tank weapons and, one might add, a miniature Luftwaffe in the form of a crated Me-262 jet fighter!
This proposition was then issued to the U-boat crew, who then refused to go along with the deal after some discussion. Rather than risk mutiny, it was decided to comply with Doenitz’s order to surrender after all. Their first opportunity came when they encountered British warships off the coast of Canada, but decided that Britain was too ‘Kaput,’ and managed to slip past their pursuers. Instead, they met with an American destroyer DD Sutton and surrendered on May 13,1945. Two days later, a fifteen-man boarding party from the Sutton boarded the U-boat and embarked 37 prisoners. Schlicke recalled the surrender well: “After a few days we got in contact with four American destroyers and that was great. There were very high seas and we had to walk to the bow of the boat carefully holding the antennae cable in our hands. A little boat then pulled up alongside us and we had to jump in. Our U-boat bobbed up and down as the Messerschmitt engineers got seasick and decided to remain aboard. When we got on the destroyer Sutton, we enjoyed the fresh air and were relieved that our long ordeal was over. Several Petty Officers were then removed from their quarters and we finally got to sleep comfortably. In the morning we received fresh bread and that was great.”
The U-234 then sailed under full escort to Portsmouth Navy Yard in New Hampshire on May 19th. The vessel was then emptied and in July checked over with a Geiger counter. Word got out later that it had carried uranium aboard.
With the high-tech cargo one may wonder why the German’s hadn’t scuttled the boat. But remember, most Germans, particularly the soldiers on the front line, believed that the Western Powers would now march with Germany against Russia.
However, five years of war under a criminal political regime had left a bitter taste in the world’s mouth. The containers of over 1,000 pounds of uranium oxide were safely offloaded by the US Navy and sent to the Manhattan Project Oak Ridge diffusion plant for reprocessing into fissionable atomic bomb material.
Despite Allied claims that the German scientists never had an inspiring creative thought, they were among the top prizes of the war, particularly the Peenemuende rocket team of Dr. Wernher von Braun. A battle of intrigue was then waged between Russia and the West in a mad race to get the best German brains. In the United States, the procurement of the German scientists was known as project PAPERCLIP. In war-torn Germany, the Russian agents were also active in their efforts, kidnapping scientists and technicians as they scoured the war torn countryside looking for talent.
The P.O.W. conditions for the average German soldier were quite poor. But for some of the scientists and engineers, their standard of living actually improved. Pulled out of the rubble heap of a nation now facing starvation, some of the scientists were able to enjoy luxuries as cake and ice cream. Schlicke himself had access to the Turkish baths during his stay in the Gould Estate in Long Island, New York.
But before all the luxuries could be enjoyed, he also hungered in the P.O.W. camp in Oberursel near Frankfurt and was thoroughly interrogated by the Americans. Confident that his knowledge and information would be used against the Soviets, Schlicke gave a series of lectures on German technology to the US Bureau of Ships in the United States. At the time the Doctor’s English was quite poor, so he had lectured in German. The twenty or so American engineers and physicists would frequently interrupt him to demand, “What in the hell does this word mean?” Their frustrations were actually quite understandable: “Scientific German is very complex with long sentences and words,” Schlicke admitted. For example, Grosskreisbreitbandgruppenpeilanlage literally meant ‘a large circle of antennas!’”
Eventually there were several PAPERCLIP German scientists working on different projects in Long Island at the US Office of Naval Research. Dr. Schlicke spent some time working on aircraft carrier landing simulation, radar camouflage techniques, and the effects of radioactive fallout from nuclear weapons. After meeting his obligation to the US Navy Research Field, he left and later moved to Milwaukee, Wisconsin, where he became the Chief Scientist at the Allen Bradley Corporation concerned with development of critical TV components and high frequency filters. After leaving Allen Bradley in 1975 he continued to be self employed as a consulting engineer on the prevention of electrical noise and hazards in industry. He was also called in as an expert in complicated industrial accident cases.
He had written sixty scientific papers, two scientific books, co-authored on four others, holds over twenty patents, among them, the command destruct filters on the USAF Minuteman guided missiles. He was twice president of the EMC Society of the Institute of Electrical and Electronic Engineers, and twice distinguished lecturer at MIT. Schlicke also served as the US delegate to the USSR in a State Department Scientific Exchange program. It is interesting to note that the doctor eventually arrived in Japan in 1964 while on a business trip.
The remarkable and scientifically important voyage of this U-234 was the subject of two media productions by Andreas Gutzeit, Das Letzte Boot (The Last Boat), a 1992 German made-for-TV movie based on the voyage, and Discovery Channel program entitled, U-234: Hitler’s Last Submarine, released in 2001 by International Historical Films, in which Dr. Schlicke gave his historical perspective on the incident. He passed away in 2006 in Florida at the age of 93.
Rolf Stibbe is a contributing writer to the Shingetsu News Agency