The National Defense Research laboratories experimented with lightweight incendiary bombs, and produced a design weighing less than 1oz (28g), including the weight of the small timed fuse that would ignite the package. Adams and his team were meanwhile reported to have visited literally thousands of caves to collect guano bats, which were large enough to carry the little bombs. Some trial flights were made at Muroc Lake in California but they were farcical — the bats were disorientated and flew straight into the ground. A batch of the bats, experimentally fitted with their bombs, later escaped from their shed at an army base in New Mexico and set fire to an aircraft hangar and the military vehicle inside. The United States government response was to take the project away from Adams and his friends, and hand it to the authority of the Marine Corps. They code named it Project X-ray, and abandoned the idea soon afterwards.
Conventional incendiary attacks against Japan were soon intensified. The Germans had introduced the concept of fire-bombing civilians with the destruction of Warsaw in 1939. They next burned Rotterdam, even though that city had already capitulated. German forces carried out firebombing raids on an even larger scale with the night-time attacks of London in 1940–41. This led to what is now called ‘shock and awe’ — the widely televised raids on Baghdad during the Iraq War of 2003–10 are a more recent example of the same tactic. This indiscriminate bombing of heavily populated civilian areas early in World War II seems terrifying to us now, but it was soon to be adopted by the Allies. Hamburg was virtually destroyed by Allied bombing in 1943, and the huge conflagration that the bombs caused led to the death of about 50,000 people, most of them civilians. The destruction of Dresden in 1945 was a later example, by the Royal Air Force and the United States Air Force. Some 1,300 heavy bombers delivered a massive onslaught of almost 4,000 tons of bombs which destroyed 15 square miles (about 40km2) of that historic city. Though there have been many claims that the bridges and industrial complexes were important targets, there is no evidence that these were bombed specifically. Estimates of the number of deaths at the time were as high as 250,000, though it has since been thought that this could be as much as ten times higher than the real figure.
After the attacks on Pearl Harbor, squadrons of B-29 Superfortress bombers were sent to fire-bomb Japanese cities with devastating consequences. In Operation Meetinghouse, 100,000 civilians in Tokyo were burned and blasted to their deaths. Altogether, 500,000 Japanese were killed during World War II and 5,000,000 were left homeless. And so — even though the bat bombs of Project X-ray were a failure — the Japanese cities were burned after all.
These were not the only experiments to use living creatures as secret weapons. After the attempts to use bats in the war came another project — using pigeons. United States psychologist B. F. Skinner conceived of a scheme to train pigeons to guide missiles against the enemy. His idea was to condition pigeons — by offering them rewards of food — so that they would peck continuously at an image of an enemy warship projected onto a screen inside the tiny cockpit of a Pelican guided missile. As long as the pecking was in the middle of the screen, the missile flew straight towards the target, but if the image was projected to one side, then the pecking of the pigeon would cause the steering system of the missile to correct its trajectory until the picture of the target was once more back on course. The United States National Defense Research Committee was dubious about the idea, but Skinner claimed that, if the missile was released within 2,000ft (about 600m) of the enemy ship, the pigeon on board would guarantee success. Skinner had a high profile as a result of his fashionable ideas, and was considered to be the man of the moment so $25,000 was donated to fund the research. The development came to naught, and in October 1944 the military support was withdrawn — but not for long. In 1948 the United States Navy revived the research under the code name Project Orcon and it survived until 1953, by which time electronic guidance was sufficiently reliable and the pigeons were retired.
Anti-tank weapons were always sought by both sides, and an innovation by the Soviets during World War II was the anti-tank dog. These animals were trained to find their food beneath a tank, and were released before a raid. Each of the dogs had a bomb strapped to its back with a sensitive lever fitted to the detonator that would be triggered when the dogs ran underneath a tank to find food.
The animals were left hungry for two days prior to an attack, and were then released against the enemy tank positions. They ran towards the tanks to find food, and immediately burrowed underneath. The lever was touched, and the bomb violently exploded. It is estimated that some 300 German tanks were damaged by these dog-borne bombs during the course of World War II. However, because the dogs were trained with Russian vehicles, they often homed in on Soviet troops rather than the unfamiliar scent of the exhaust from German tanks.
Giant guns are a staple in warfare. It was the existence of the supposedly impregnable Maginot Line that marked the eastern boundary of France which had provided the stimulus for the development of Germany’s monster guns. The artillery specialist General Carl Becker designed these huge weapons which were manufactured by the Rheinmetall-Borsig Company who named them Karl Gerät 040 after their inventor. The manufacture of these monstrous siege guns started in 1937. They were unmanageable weapons, weighing 124 tons and moving at no more than walking pace. They could be transported by rail as a massive self-contained wagon. Six were manufactured between November 1940 and August 1941. They were designed to fire huge shells of 60 or 54cm (about 2ft) in diameter and produced an enormous recoil when fired. Both wars were known for giant guns, from Big Bertha in World War I, weighing 43 tons, to the Gustav Gun of World War II, which weighed 1,344 tons. They all have a place in military history — though they cannot be classed as ‘secret’.
One giant gun can be included in our exploration of the world of secret weapons, however, for it was constructed beneath the ground and the Germans went to great lengths to ensure that nobody would find out about it before the planned attacks began. It was envisaged that the Allies — even when they experienced the effects of bombardment — would never discover where it had originated. The device had several names: Hochdruckpumpe (HDP, high-pressure pump); Fleissiges Lieschen (Busy Lizzie); Tausendfüssler (Centipede, though the literal translation is ‘millipede’). It was sometimes even referred to as the V-3 (Vergeltungswaffe-3). Later designs were so novel and potentially far-reaching that it was felt to be in an exclusive class of secret weapons. This multi-charge super-gun was an invention of the Röchling Stahlwerk AG establishment and it took the form of a sectional barrel with paired side-branches like ribs on a fish-bone. In these lateral chambers would be explosive charges, which could be fired automatically in sequence. As the projectile passed each of the branches, the next charge in the sequence would detonate, so building up the pressure until the missile was launched with the formidable velocity of 4,500ft/s (1,370m/s) or 3,000mph (4,800km/h). It was intended to be constructed in subterranean bunkers near the Pas-de-Calais region of northern France and used to rain missiles down on London. The first such weapon was designed in 1943 by an engineer named August Cönders of the Röchling Stahlwerk factory. He had designed the Röchling shells, ingenious bombs that could penetrate up to 14ft (4.25m) of reinforced concrete. These shells were regarded by the Germans as a secret weapon in themselves. They were inaccurate, but were impressive enough to be recommended by the Minister of Munitions, Albert Speer. Cönders was instructed to design a prototype Hochdruckpumpe and produced one with just 20mm (about.75in) bore; however, the tests showed that the idea could work. The research was mentioned to Hitler who immediately concluded that 50 of the full-sized weapons should be installed along the coast of northern France to bombard London incessantly.