Being the occasionally interesting ramblings of a major-league technophile.
Please note that while I am an engineer (BSCE) and do my research, I am not a professional in this field. Do not take anything here as gospel; check the facts I give. And if you find a mistake, please let me know about it.
John W. Campbell contended that the Romans had a secret weapon which was responsible for many of their military victories. It was something in plain sight, but outside the mindset of most of their enemies. Because to those enemies it was individual valor in fighting which was important. They believed that any one of them was worth at least two Legionnaires. And they were right. Those short Roman swords just weren't as effective in single combat as the longer, heavier swords of - say - the Germanic tribes. But, as mentioned above, the Romans had a secret weapon. Something clearly visible to anyone able to look past the concept of fighting for personal glory. That weapon was group tactics. The Roman Legion's short swords, large shields and spears were ideally suited for the sort of mutually supportive fighting practiced by the Legionnaires.
A secret weapon is anything which gives an advantage over an enemy, and which the enemy does not know about. (Though they may know of it.) It can be an actual, physical weapon. It can be a way of fighting, as described above. It can be something which indirectly supports military activity, such as a free market economy, in which competition weeds out inefficient manufacturers and stimulates innovation. For a secret weapon to work, there must exist conditions which will allow it to be developed and employed without the enemy learning about it, or, having learned about it, appreciate it. The best secret weapons in history resulted from an accepting atmosphere which permitted them to come about, a willingness on the part of those in charge to try them, and an ability or circumstances which kept the enemy from learning about them until too late. Closed minds and secret weapons rarely work well together. A prime example of both secret weapon development and their application beind hindered by the unimaginative is the use of radar in the Second World War. (Much of the technology discussed here is from that era. That is long enough ago that most of the secret information has been declassified. Also, this was a period of frantic military invention unrivaled in history.)
In the late Thirties the Germans had probably the best radars in the world, fixed and portable units operating in the 50 centimeter band. This was a very short wavelength for the technology of the day. In 1939 the Germans noticed what appeared to be radio broadcast stations being erected along the British east coast. The natural suspicion was that they were radar installations. However, these sites used tall towers set well apart, with wires strung between them, all wrong for shortwave radar. The Germans wanted to know what these were. One method they used to check was to equip two Zeppelins with radio receivers and fly them near the sites. They detected nothing beyond natural static and some remote radio noise. Yet the British technicians clearly saw the huge blips on their radar screens. Why did the Germans fail to even detect the powerful signals the British units were bathing them in?
The British radar sets were operating on extremely long wavelengths, in the 10 meter band. Something the Germans should have suspected because of the size of the antennas. However, because they assumed that British radar development had followed a course similar to their own, they didn't even have equipment on board the Zeppelins to detect emissions in those frequency ranges. (Note that this choice of frequency by the British was not due to technical backwardness, but was deliberately selected for the role these stations were intended to play. The equipment was designed to cover as much of the coastline as possible with as few installations as possible, necessitating long wavelengths. The British later added to their coastal warning system radar sets operating in the 1.5 meter band for detecting low-flying aircraft.)
Later in the War, the Germans made a similar mistake in the opposite direction, but this time the mistake was much more understandable. It was also much costlier.
Physics tells us that the shorter the wavelength used, the better the range and discrimination of the radar system. For practical reasons radiation in the microwave frequencies is generally the best choice. However, microwaves are difficult to produce with tubes. There had been some development in the Thirties, even demonstrations in which microwaves were used to cook food. But when radar was being developed the researchers concentrated on longer radio waves, because everybody knew that it was too hard to produce a powerful enough beam in microwave frequencies. Tubes just weren't up to the job. (This is a matter of physics, not technology. Even small tubes are a significant portion of a microwave wavelength long, which leads to problems inside the tube.)
In the winter of 1939-1940 British scientists Dr. (later Sir) John Randal and Dr. Harry Boot developed the cavity magnetron, which was a major improvement over the previously existing split-anode magnetron. This device opened a whole new vista for Allied radar developers. Radar sets could be made smaller, more powerful, more accurate, more discerning, more reliable and given greater range. The first of these sets (including the famed H2S airborne radar) operated in the 10 cm range. Later WWII units went down to 3 cm.
Microwave radar sets were used both on the ground and in the air, the latter for bombing at night and through clouds and in specialized fighters for shooting down enemy bombers in the dark. (Previous airborne radars used by both sides operated at longer wavelengths, which allowed them to spot aircraft but not resolve ground targets.) The sets worked wonderfully well, but the Allied commanders were worried. They knew the Germans still hadn't hit on the idea of the magnetron. What if one of the bombers carrying a microwave set over Europe was shot down and the magnetron found?
Various efforts at misdirection were used to maintain the secret. For instance, to explain the increasing accuracy of night bombing and the improved success the night fighters were having, a famous bit of flummery was instituted. One which continues - though unintentionally - to this day. Newsreels and newspapers carried stories about how bombardiers and pilots were being fed extra carrots to improve their night vision. In truth, while Vitamin A supplementation can help someone with night-blindness caused by a deficiency, someone who already has normal night vision will not experience any improvement. But just try telling that to millions of mothers!
Still, the Allied commanders continued to worry. The Germans had some clever people, and all it would take was one good hint for them to figure out what was happening. And something as strange as a cavity magnetron, hooked up to what was obviously a radar set, was a very good hint. Worse, the magnetron was essentially a milled block of copper, and very hard to damage enough to disguise its characteristics. It would probably survive a crash, and even a destruct charge. The new radar sets were too beneficial to leave out, though, so their use continued.
Eventually one of the planes carrying a microwave radar bombing set was shot down. And the mysterious electronic gadget with the even more mysterious device inside was turned over to German electronics experts. And their verdict was, "We don't know what this thing is, but we know for certain it has nothing to do with radar." Because they knew that microwaves could not be used for radar. And they could tell from the construction of the rest of the device that it operated at microwave frequencies. Therefore, this must be a clever bit of misdirection on the part of the Allies.
This was not a one-time mistake. German researchers were working on thermal and near-visible infrared night vision devices. When Allied warships and naval patrol bombers began sinking U-boats with disturbing regularity at night, while the submarines were on the surface recharging their batteries, the first idea was that radar sets in the ships and planes were responsible. But the long-wave and shortwave radar detectors (which had served to give warning previously, against older Allied radars) in the submarines didn't react. Therefore it was decided that the Allies must be using IR equipment to spot the warm conning tower against the cool sea. Many man-hours were wasted in creating, manufacturing and installing heat baffles on the conning towers. And the submarines kept getting sunk, because the baffle material was transparent to radio waves.
So the Schnorkle was invented. (Adopted from an invention by a conquered country, actually.) This allowed the submarines to stay submerged while taking in air and exhausting fumes through tubes projecting above the surface. And still they got sunk by bombers. It wasn't IR. It wasn't radar (that they could detect, that is). What was it?
Of course, because the German radar experts knew that microwave radar was impossible, they didn't notice that the Schnorkle was a good length to resonate at microwave frequencies.
The situation didn't last, of course. Eventually the Germans did capture a nearly complete H2S radar and decipher it, and put their own microwave radar into production. A radar-absorbent covering was developed for the Schnorkle, but it wasn't really practical. (It worked, but washed away too easily.) The Germans also supplemented the Metox radar warning sets in the submarines with the Naxos unit, which could detect the 10 cm band radar. For the next two years the advantage see-sawed back and forth, but the German submarines never again were as effective against convoys as they had been during the early part of the Battle of the Atlantic.
The Ultra secret is another example of how arrogant minds make arrogant mistakes. The German High Command was so impressed (and infatuated) with the Enigma code machine that they ignored the machine's weaknesses. And for all its technical sophistication and brilliance, there were weaknesses. For instance, no letter could stand for itself. Also, all numbers had to be spelled out, since the machines had no number keys. These and other features gave Allied code breakers toeholds for working on the messages the Enigma machines encrypted. Eventually, after a couple of lucky breaks and a great deal of help from Polish and other operatives in occupied countries, the code breakers succeeded. (Several books could be - and have been - written on the development of fast, programmable computers made just to defeat Enigma and similar coding machines.) The German secret weapon had been defeated. (And, despite what J. Michael Straczynski thinks, the story of Churchill and the Coventry bombing is a myth. However, it is true that officers using information provided by Ultra were under orders never to take action based on intelligence gained through it that could not have been obtained from other sources.)
Note that there were several versions of the Enigma machine operated by the Nazis. They were in use for over two decades, constantly upgraded and with different models for different purposes. For instance, the Army and Luftwaffe used one model and the Navy another. Neither type of Enigma could decode the messages of the other. This made things more complicated for the Allied code breakers, since they had to break the coding of each machine separately. However, break these codes they did.
The Nazi leaders were so impressed with the numerical complexities of the Enigma machines, and by the constant upgrades made to them throughout the War, that they made it policy that the Enigma code was unbreakable. When field commanders began reporting their suspicions that coded messages were being intercepted and decoded, they were told this was impossible. The intelligence leaks must be due to security problems on site. (Note that the possibility of a message eventually being decoded was accepted, but the assumption was made that the effort required was so great that by the time an enemy had done so, the information in the message would be outdated. Remember the fast, programmable computers mentioned above? The Germans didn't know about those particular secret weapons.)
Of course, the Germans weren't the only ones occasionally hampered by hubris. Mention was made above about their efforts with the IR viewing system. These resulted in the first night vision scopes, using near-visible IR lamps and a somewhat cumbersome electronic viewing device. This development came as rather an unpleasant surprise to the Allies.
A more spectacular failure in Allied technical judgment occurred in regard to the V-2 rocket. Today it is almost amusing to read the minutes of staff meetings where the mysterious series of explosions caused by the first V-2 rockets to land in Britain were discussed. There were so many reasons given so emphatically by various munitions and science experts as to why none of the suggested methods (including large rockets) could possibly work that one almost expects to read that the committee concluded the explosions never actually happened! (This is an exaggeration, of course. By the time the first V-2 hit Brittain the Allies had some very good estimates of size, payload and range. However, they also had contradictory estimates of those values from equally prominant experts!)
Sometimes a weapon can have effects that are secret even from the people using it. The Parachute and Cable (or PAC) was a British weapon intended to bring down German bombers. The idea was that a cable would be lifted into the air by a rocket into the path of a bomber. The bottom end of the cable carried an explosive device, and there was a parachute at the top. The parachute served two functions. Once the rocket burned out the canopy slowed the cable's fall, and if the cable caught a bomber's wing the drag from the parachute would pull the cable across the wing until the explosive made contact and detonated. (Early versions simply had a second parachute at the bottom, with no explosive. They were intended to entangle propellers. Later variations included hanging the cables from barrage balloons.) Proponents of PAC expected Nazi bombers to drop from the skies in droves.
At first the weapon seemed to have - at best - limited effectiveness. Some enemy aircraft were downed, but far more simply flew away after clear hits. PAC began to fall out of favor. But then interesting reports began coming in, from interrogations of captured German pilots, and conversations overheard by underground operatives across the Channel. These accounts related horror stories of engines going dead, later to be found mysteriously tangled in what looked like huge lengths of piano wire. Worse, the cable had a parachute on one end, creating high drag on the side with the dead engine. As a final terror, on landing a dangling explosive charge could blow up the plane, damage the runway or both! And if the cable didn't catch on something, but dragged across the wing, it sawed through the metal! (Several aircraft are documented as having a wing pulled off simply by the shock of impact with the cable, including a Wellington bomber used in early trials.)
Other accounts soon supported the effectiveness of the device. A few aircraft were unfortunate enough to pick up several PAC at once. These were rapidly dragged to a stall and literally fell out of the air! Imagine the effect seeing this had on the crews of other German bombers in the same formation.
So while the PAC wasn't nearly as effective at directly downing bombers as hoped, it definitely had an adverse effect on German aircrew morale. However, the PAC was not really a success for defending Britain. For one thing, it wasn't as accurate as traditional antiaircraft fire, which was steadily improving. The device never really worked like it should have, either. In addition there were safety concerns. The explosive charges were supposed to self-destruct before reaching the ground. Unfortunately, they didn't always, thus creating a hazard for unsuspecting civilians. There was also the problem of dropping steel cables across electrical transmission wires. And all that steel could be put to better use in other applications.
Sea-borne versions were less problematical in many of these respects, and so the PAC was much more often used aboard ships than on land. The ocean going PAC - placed mostly aboard small ships, such as merchant marine vessels, which didn't have the room or the crew for the heavy antiaircraft defenses of large military craft - is credited with downing 9 enemy aircraft.
Though it started out as a secret weapon, the Parachute and Cable was too spectacular in its operation to remain one, and was actually taken off the Secret List in 1943.
Which brings us back to the problem of how to keep something secret when you need to use it. The developments of such devices as the V-2 ballistic rocket and the Me262 jet fighter were kept secret (though some clues inevitably leaked out in both cases, the Allies didn't really know many particulars early on). Once the weapons were put to use they quickly became known. Still, the details involved in their construction and operation remained secret and much effort was expended attempting to learn them. Some of this work took the form of espionage, and some of scavenging. At one point, the Swiss underground got to the crash site of a test V-2 before the Germans did and hid large portions of the wreckage. These parts were later shipped to England, where they provided important clues as to the capabilities of the V-2.
Even so, the Allies never developed anything like it. The V-1 was duplicated (the American version was known as the Loon) but never saw much actual use by the Allies. The V-2, though, was unique to the Germans. All of those used by the Allies after the war were captured, not copied. By the time Allied rocket technology caught up with that of the Nazis, the science of rocketry had advanced beyond the V-2. The same was true with the Me262 Swallow jet fighter. The first Allied jet fighters were much less advanced than the Me262; the second generation was much more advanced, in large part due to what was learned from the Germans.
One way to keep the use of a secret weapon for yourself after it is no longer a secret is to use the period of secrecy to advance far ahead of your enemies to keep them from copying your weapon before the war is over. Of course, if you don't win...
Another class of secret weapon entirely is the stuff of spy and espionage tales. The amount of equipment - and the wide variety of types of it - which has been placed in uniform buttons and boot heels, sewn into jacket linings and glued into book covers is astounding. However, this stuff is less secret than simply hidden. Both sides not only do the same things but expect it of the other side. So this class of object doesn't really come under the scope of this article.
The most famous secret weapon of all time is - of course - the fission bomb. Except that it was never really a secret. Nature is an impartial witness; ask the right question and you'll get a useful answer, no matter what your politics.
Otto Hahn was the first to publish speculation on the possibility of a uranium nuclear chain reaction in a scientific journal. He was also involved in German nuclear research during the War. Several other renowned nuclear physicists - including Werner Heisenberg - were also involved in German nuclear research. Furthermore the Germans had the best research and industrial chemists in the world. Small wonder Einstein and other Allied scientists were concerned about the possibility of the Nazis developing a nuclear bomb. Why didn't they? There is considerable evidence that Heisenberg quietly diverted German research in the wrong direction. Also, there was a war on, and the High Command could see that a nuclear weapon would take too long and require too many resources to be ready for use in the short war they expected. Therefore, German nuclear research focused on other potential uses.
After the dropping of the Little Boy bomb on Hiroshima, Heisenberg and a number of other German physicists - being held in a chateau as civilian prisoners of war - speculated on how the bomb worked. A photo of the sketch Heisenberg drew on a blackboard was shown to physicists working on the Manhattan Project. They were spooked by how much he got right.
As for the Russians, some of their scientists were speculating on uranium chain reactions by 1939, following announcement of German experiments with neutron bombardment of uranium (performed by Hahn and Fritz Straussmann). They recognized the same problems that deterred the Germans, but the Soviets were expecting a long war. Moreover, they expected the Germans to also be planning for a long war, and therefore to be researching fission weapons. The official Soviet bomb research program was started in the middle of 1941, shortly after the German invasion.
Due to the dislocations this event caused, most of the early research was theoretical. (Ironically, the primary function of Soviet espionage into Allied bomb research was to verify theories which the Soviets could not check out themselves, due to the lack of facilities. The possibility of a bomb was long known, and some Russian physicists deduced the existence of the Allied bomb program from the simple fact that foreign physics journals were no longer carrying articles on nuclear fission!)
There are a great many more secret weapons. Most never went beyond the idea stage. Most of those which reached trials never became operational. (It would have been interesting to see the faces of German soldiers defending the beaches of Normandy as a Great Panjandrum came roaring and flaming towards them.) Many of those which did actually see service were soon dropped or replaced by something more conventional. And some were so successful that they still officially do not exist, remaining secret 10, 20, even sixty years later.
This document is Copyright 2004 Rodford Edmiston Smith. Anyone wishing to repost it must have permission from the author, who can be reached at: stickmaker@usa.net