Cönders began to construct a full-sized test gun at Hillersleben near Magdeburg. It proved impossible to find the best sealing mechanism along the barrel, and so the gun could not be induced to fire reliably. On the few occasions that the device worked, the projectile was shot out too slowly. Hitler would not be dissuaded, and plans were put in place to build a 490ft (150m) gun on the Baltic island of Wolin, near Peenemünde. These Baltic tests proved to be no more successful, and so the Army Ordnance Bureau (Heereswaffenamt) was ordered to take over the development and Cönders was appointed to be a chief engineer. Hitler’s driving ambition — to have a super-gun sending a cascade of high-explosive bombs to London — meant that by the middle of 1944 there were four designs for the 150mm finned projectiles, all separately manufactured by Fasterstoff, Bochumer, Witkowitz and Röchling.
Further urgent tests took place in the Baltic. More effective seals were used, which not only held the explosive charge behind the moving projectile, but also prevented premature ignition of the charges further along the barrel. During 1944 the success rates improved, and some of the projectiles landed some 50 miles (80km) from the gun that launched them. In July 1944 eight consecutive rounds were test-fired from the gun on Wolin but then it burst violently and further use was impossible.
Nonetheless, Hitler ordered that sites be found for the installation of the gun in France. One was at a limestone hill 3 miles (5km) from the Hidrequent quarry near Mimoyecques in Pas-de-Calais, a region of northern France near Cap Gris Nez, where V-1 and V-2 rocket sites were already being constructed. The site was 5 miles (8km) from the coast of the English Channel and 100 miles (160km) from London. In September 1943 construction of the railway track began, and work started on digging out the gun shafts. Two identical sites were worked on simultaneously, about 3,300ft (1,000m) apart. They contained provision for up to 50 of these giant guns, an extraordinary amount.
In London, British Intelligence learned something was afoot and orders were given for routine aerial reconnaissance photographs of the work. Within weeks, plans were laid by the Allies and air raids started on 5 November 1943 during Operation Crossbow. Some workers were killed in the raids, and the excavations were damaged but work continued. The Germans planned to have the first groups of five guns complete and ready to be commissioned in March 1944. Tests in the Baltic were still a disappointment; the guns had not been proved to work reliably, and so this work was curtailed. Then in July 1944, the War Ministry in London issued orders that the emplacement be attacked with the 12,000lb (5,400kg) Tallboy deep-penetration bombs that had been designed by Barnes Wallis. The weapons were to be dropped by 617 Squadron, still under the command of Guy Gibson, who had proved themselves in the Dambuster raid. The resulting destruction at Mimoyecques was so extensive that all work ground to a halt.
After the war, a joint project between the United States Department of Defense and the Canadian Department of National Defence revived something similar. It was a project to see if a satellite could be launched from a massive gun, and was entitled the High Altitude Research Project (or HARP). It was the idea of a Canadian ballistics engineer named Gerald Bull. Trials were carried out from a test range at Seawell Airport, Barbados. Bull’s experimental team eventually fired a test missile weighing 400lb (180kg) at 8,000mph (13,000km/h) to an altitude of 112 miles (180km). It was an extraordinary achievement. Buildings and private homes for miles around reported the damage caused by the powerful shock-waves — cracked sinks, split concrete, damaged walls — which the authorities refused to entertain.
Bull remained as fixated as Hitler on the lure of a super-gun, and kept on with his research even after support was withdrawn by the United States and Canadian governments. He sold a giant gun to South Africa and was gaoled in the United States for breaching the trade embargo then in force. After his release, Bull moved to Brussels, Belgium, and negotiated a deal for the development of a satellite launch (code named Project Babylon) with Saddam Hussein. In March 1990 Bull was shot dead in his Brussels apartment, reportedly by agents of Mossad, the Israeli secret service. Parts of his super-gun were later impounded by the British customs authorities as an illegal export (as of 2011, parts of an Iraqi super-gun are held at the Imperial War Museum, Duxford, UK). It was a remarkable end to a saga that had its roots in the wild ambitions of Hitler in wartime Nazi Germany.
George Johnstone Stoney was the Irish scientist who coined the term ‘electron’ in 1894, and three years later J. J. Thomson at Cambridge University first recorded the existence of this subatomic unit. A French scientist, Antoine Henri Becquerel, discovered radioactivity accidentally in 1896 when he noticed that uranium fogged a photographic plate, even in the dark. In 1932 Ernest Rutherford, the father of nuclear physics, set up an experiment in Cambridge in which the splitting of the nucleus was observed; also in Cambridge, and during the same year, James Chadwick first observed the neutron. During 1938, Otto Hahn and Fritz Straßman showed that the fragments of the split atoms weighed about half as much as the original uranium nuclei — they had split the atoms in two (for this crucial discovery, Hahn was awarded the Nobel Prize in 1944). Hahn published these results at once, and sent the details to his friend Lise Meitner who was working in Stockholm. With her nephew, Otto Frisch, she soon calculated that colossal amounts of energy would be released in a sustained nuclear reaction. The short paper announcing the work by these two physicists appeared in the journal Nature in 1939, and the matter was suddenly out in the open. The next crucial publication came from a French physicist, Frédéric Joliot in Paris; he showed that, when the atomic nuclei were split in two, neutrons were ejected — and they would trigger a chain reaction.
The whole scientific world could now see that an atomic bomb could be manufactured: now it was only a matter of time.
Within weeks, German scientists pooled their ideas and formed the Uranverein (Uranium Club). Word spread, and three émigré Jewish scientists in the United States, Albert Einstein, Leo Szilard and Eugene Wigner, sent a note to President Roosevelt to warn him of the Nazis’ intention of constructing an atomic weapon. Some months later the German Army Ordnance Office began to compile reports on a possible Uranmaschine (a nuclear reactor) and on methods of purifying uranium isotopes. The consensus was that a nuclear reaction could clearly liberate huge amounts of energy, but that it would take years to perfect. The war was going well at that time, and so policies turned against the idea and the research was divided up among institutes scattered across Germany — laboratories in Berlin, Cologne, Hamburg, Heidelberg and Leipzig were among the many that were charged with carrying on nuclear research. The brilliant young physicist Carl Friedrich von Weizsäcker (whose brother Richard later became President of the Federal Republic of Germany) was an ardent supporter of Adolf Hitler at the time, sensing the atmosphere of renewal and expansion that was everywhere in Germany, and enthusiastically began work on atomic research. Ten of the German atomic scientists were secretly recorded in discussion at the end of the war in late 1945: Erich Bagge, Kurt Diebner, Walther Gerlach, Otto Hahn, Paul Harteck, Werner Heisenberg, Horst Korsching, Max von Laue, Carl Friedrich von Weizsäcker and Karl Wirtz. The transcripts were not declassified until 1992 and they proved to be inconclusive about the motives and ambitions of these scientists. A public airing was presented as a radio play entitled Nuclear Reactions, written by Adam Ganz and transmitted by the BBC on 15 June 2010.