When the date for the declaration of open and unrestricted submarine warfare came on 1 February, the Americans broke off diplomatic relations with Germany and proclaimed a policy of ‘armed neutrality’. But nothing further happened. As a man of peace, President Wilson was clearly not about to declare war. So, on 5 February, Hall decided to share his secret with the Foreign Office. He paid a visit to Lord Hardinge, the Permanent Secretary, and laid out what he knew, asking to enlist Balfour’s support. Hall wrote that Hardinge was ‘his usual cool self, interested but cautious’.13 The remarkable intelligence discovered by Room 40 would now begin to work its way through the slow-moving bureaucracy of the Foreign Office.
While Hall was waiting for a decision from the Foreign Office, another deciphered exchange between Mexico and Berlin landed on his desk. The Americans had sent a military posse into Mexico to pursue a bandit who had been raiding across the American border. It seemed that President Carranza was deeply upset by American military action within his country and he now told Berlin that he was definitely interested in the possibility of German support for an invasion of the southern states of America and was favourable to Mexico’s naval bases being used for German submarines. Hall decided he had to inform the Americans.
Calling in an intelligence officer from the US embassy in London, Ed Bell, Hall showed him the full text of the so-called Zimmermann Telegram. Bell exploded with rage when he read about covert German support for an invasion of his country, but after a moment’s reflection he said it was so outrageous that it must be a hoax. Hall persuaded him that the telegram was authentic. ‘This means war’ Bell concluded. ‘Only if it is published,’ replied Hall, who now explained to the American that he could do nothing without Foreign Office approval.
Rapidly, the American ambassador in London, Dr Walter Hines Page, became involved. A great Anglophile who for some time had tried to persuade the President to join the Allied war effort, Page must have been champing at the bit to get news of the secret cable back to Washington. But Hall’s persuasive powers were so great that he convinced Page to hold off until the Foreign Secretary had decided how to proceed.
Events were beginning to move rapidly. Balfour resolved that the best way to proceed was for Hall to inform the US embassy of the existence of the Zimmerman Telegram himself. He knew and respected Hall from his days at the Admiralty and minuted, ‘I think Captain Hall may be left to clinch this problem. He knows the ropes better than anyone.’14 Of course, Hall was one step ahead of Balfour and had already informed the ambassador. Between them, Hall and the two Americans, Bell and Page, then concocted a masterly plan for the release of the information. They realised that if it was announced that the Americans had themselves discovered the intelligence then no suspicion would fall on Room 40. And of course Berlin had sent the Zimmermann Telegram to Washington as an extension of another message being sent to their ambassador. If the Americans found and deciphered that cable in their own State Department inbox, then they could take credit for the intelligence coup. The only problem was that the American secret service did not have the code books necessary to decipher the message.
Page met Balfour on 23 February. The Foreign Secretary formally gave the American ambassador a coded copy of the Zimmermann Telegram and Page returned to the American embassy with it. Nigel de Grey then went to the embassy and, with Bell, deciphered the telegram. As the American embassy was legally a part of the United States of America, the diplomats could now correctly claim that the telegram had been deciphered on American soil. Page then sent to the President and the Secretary of State a message that included a translation of the telegram, confirming exactly where in the message trail at the Washington cable office they could find the original.
There was a short delay in Washington while Wilson and his Secretary of State, Robert Lansing, decided what to do with this astonishing piece of intelligence. They asked for a copy of the code books to be sent to Washington so their own code breakers could go back over the diplomatic cables at the State Department. At Hall’s insistence, the government refused this request. The Foreign Office explained to the Americans that the Germans never used only a single code, but jumbled several together in one message, and that only a few experts were able to decipher the completed message. Instead, the British government offered to decipher anything the Americans wished to read.
Within a few days, the Zimmermann Telegram was passed on to the American press. As anticipated, the American public were outraged. Many Americans believed the telegram to be a forgery, even perhaps that Britain had put it out in order to draw the United States into the war. President Wilson insisted it was authentic and had been deciphered by Americans. Then, on the following day, Zimmermann himself admitted at a press conference in Berlin that the telegram was genuine. The peace-loving President and the American people had to accept that Germany had been planning to assist a neighbouring government to invade their country. Within a month, the President recalled Congress and on 6 April 1917, the United States declared war on Germany.
In Germany, there was an investigation into how the telegram had been intercepted. The American press was full of wild stories. One told of how backwoodsmen from Arizona had smuggled themselves into a German communications centre in Brussels and stolen the crucial code book. Others told of Americans paying huge sums to buy the code books from renegade German officials. Yet more described how American secret servicemen had broken into a trunk owned by the Swedish ambassador in Washington and found the telegram there. While such accounts were probably dismissed in Berlin, the German Foreign Ministry interrogated its ambassador in Mexico, thinking his embassy might be the weak link in their communication chain. When this was ruled out, they concluded there must have been a leak in Washington. Meanwhile, Hall followed decrypts of the exchanges, noting to his delight that Berlin carried on using the same ciphers.
Not only did Room 40 continue deciphering messages from Berlin uninterrupted, but Hall himself came in for high-level praise from Washington. The President sent a letter to Page in London asking him ‘at an early time … to assure Admiral Hall of my very great appreciation of what he has done and of the spirit in which he has done it’.15 In a cable to a British official, Hall proudly boasted with unusual directness and honesty, ‘Alone I did it.’16
It was an outcome that must have astonished even the wily Hall. America had declared war on Germany. The Germans thought the leak had occurred in Washington and continued to use the same codes on their diplomatic cables. There had been no suspicion about the existence of Room 40 or of its role in the revelations. Furthermore, the Americans had even secretly thanked Hall for everything he had done. The integrity of British intelligence had survived and the undercover work continued. Hall had done a brilliant job. At least one historian has described the story of the Zimmerman Telegram as ‘the greatest intelligence coup in history’.17
Looking back on the affair, American ambassador Walter Page wrote to President Wilson at the end of war in praise of ‘Blinker’ Hall. ‘Neither in fiction nor in fact can you find any such man to match him … The man is a genius – a clear case of genius … I do study these men here most diligently who have this vast and appalling War Job. There are uncommon creatures among them -men about whom our great-grand children will read in school histories; but of them all, the most extraordinary is this naval officer -of whom they’ll probably never hear.’18
Page was wrong in one respect. In the late 1920s and 1930s stories began to come out about Room 40 and Reginald ‘Blinker’ Hall came to be known as Britain’s ‘great spy chief’.19 Certainly, he and the extraordinary group he assembled around him had done a great deal to help the Allies win the war.
The United States of America was now in the war, but the Yanks were very slow in coming. It was just over a year before an American Expeditionary Force of a mere five divisions, led by General Pershing, engaged with German troops on the Western Front. Meanwhile, there began a catastrophic increase in the U-boats’ sinking o
f Allied ships. In April 1917, the month America declared war on Germany, one ship out of four leaving British ports never returned. Nearly one million tons of shipping, two-thirds of it British, were sunk in that single month alone. It was clear that for the war to go on the Allies would have to continue what they had been doing for two years, to try every military means they could to win it.
Part Three
Engineers and Chemists
7
The Gunners’ War
In the summer of 1914, William Lawrence Bragg had just been elected as one of the youngest Fellows of Trinity College, Cambridge. Bragg’s family, originally from Cumberland (today Cumbria), had moved to Australia in the late nineteenth century, and he was the eldest son of a renowned mathematician and physicist, a professor at Adelaide University. Bragg grew up in Australia but his family returned to Britain when he was nineteen, after his father’s appointment as Professor of Physics at Leeds University. Lawrence went up to Cambridge to read mathematics and entered an academic world that was alive with new ideas and the spirit of intellectual discovery. He became a member of a discussion group in which historians, classicists, engineers and scientists argued late into the night about the latest ideas of the time.
After his graduation, Bragg began collaborating with his father on a project to investigate the nature of X-rays. The two men were part of a circle, heavily influenced by scientists like Ernest Rutherford in Manchester and Albert Einstein in Berlin, who were doing pioneering work on atoms and electrons, and by the German physicist Wilhelm Rontgen, who had discovered X-rays. Bragg’s research soon brought him fame as the joint formulator with his father of a new law that made it possible to calculate the position of atoms within a crystal by observing how an X-ray is diffracted by the crystal’s surface. Their work gave birth to X-ray spectroscopy and the ability to study the detailed atomic nature not only of crystals but of every sort of chemical structure, and Bragg remembered it as ‘a glorious time when we worked far into every night with new worlds unfolding before us in the silent laboratory’.1 Bragg senior and junior jointly published a book entitled X-rays and Crystal Structure. For this book and the formulation of ‘Bragg’s Law’, the father-and-son partnership were jointly to be awarded a Nobel Prize. It is the only time such a team has been awarded the prize, and Lawrence Bragg, at the age of just twenty-five, was and still is the youngest person ever to become a Nobel laureate.
At the beginning of August 1914, Trinity College, Cambridge was a lively place. Bertrand Russell, the great mathematician-philosopher and one of the most respected Fellows of the college, had only a few years before co-authored Principia Mathematica, laying down the foundations of modern mathematics. Russell was amazed at the sudden turn to war and wrote a letter to the Manchester Guardian arguing that Britain should remain neutral. Had Bragg looked out of the window of his rooms into Trinity’s Great Court he would have seen Russell talking with the economist John Maynard Keynes, who was visiting his brother-in-law, another eminent scientist, Archibald Vivian Hill.2 One of the most famous scientists in Britain, Lord Rayleigh, the Nobel Prize winner and ex-president of the Royal Society, was chancellor of Cambridge University and another Fellow of Trinity College. And although still young, Bragg already had working for him a research student, Edward Victor Appleton, whose subsequent work would lay the foundations for the development of radar and win yet another Nobel Prize. Bragg was part of a glittering scientific and intellectual community with a brilliant future ahead of him.
Bragg was planning a visit to Germany to give a paper on his new law when war was declared in August. The Edwardian world of science in which new ideas had so easily crossed borders and when scholars had travelled extensively around Europe came to an abrupt end and Bragg’s trip was abandoned. Bragg had previously joined a university cavalry troop and had spent many summers at camp, training in marksmanship and horse riding, so within two weeks of the declaration of war, in a flurry of patriotism, he volunteered to join the Royal Horse Artillery. He was posted to a Leicestershire Territorial battery and spent a ghastly year in a very different world, training near Diss in Norfolk alongside the hunting and shooting set with whom he had little affinity. He wrote, ‘I was very much out of my element as my knowledge of horses was not at all extensive, and my fellow officers and men were Leicestershire hunting enthusiasts.’3
However, things changed dramatically for Bragg in the summer of 1915. The French army had been making experimental attempts to locate the position of enemy artillery from the sound of the guns firing. They were not making much progress, but the War Office thought the British Army should also pursue the idea and looked around for someone suitable to carry out the research. They approached Bragg, who leapt at the opportunity of doing original research again. In September 1915, assisted by Harold Robinson, a member of Rutherford’s team at Manchester University, Bragg was sent out to France to carry out experiments. General Headquarters of the British Army (GHQ) was based at St Omer, about thirty miles south-east of Calais.4 Its role was to support the commander-in-chief, and it included all the military intelligence and mapping sections, as well as controlling the press and censorship. Bragg and Robinson now became part of the Maps Section of GHQ.
Once again, Bragg was in his element, performing cutting-edge scientific work. He soon established the principles of what became known as ‘sound ranging’. A series of microphones would be set up in a long line over maybe six miles. When an enemy artillery piece fired, he could record the precise time at which the sound of the gun reached each microphone. From the difference in time it took for the sound to reach each microphone, it was possible using the velocity of sound to plot a series of arcs on a scale drawing. By linking these arcs a circle could be drawn, and the location of the enemy’s artillery piece would lie at the centre of the circle. Although Bragg quickly worked out the mathematical formulae for these calculations, it proved far more challenging to find microphones sensitive enough and a recording system accurate enough to record the time intervals precisely. Standard microphones picked up too many other sounds, like rifle fire or dogs barking, which made it difficult to identify the low boom of distant gunfire. It was while Bragg was setting up the first sound ranging experiments behind the front line south of Ypres that news of his Nobel Prize came through. The village curé with whom he was billeted produced a bottle of Lachryma Christi to celebrate.
During 1916, Bragg and his team continued to experiment with different forms of low-frequency microphones, finally opting for a device with a heated platinum wire that cooled when hit by the sound wave of the gun’s detonation. This acted as a reliable apparatus for filtering out all other sounds and recording the distant explosion of the enemy gun. By the end of the year, Bragg had also found a way to record the time interval between the arrival of the sound waves at several different low-frequency microphones with enough sensitivity to operate an efficient system. But the recordings were useless when the wind was blowing in the direction of the German lines, as it frequently did. At GHQ they began to lose patience with the young man whose ideas so few of the senior officers could even begin to understand. However, Colonel Edward Jack, the officer in charge of the Maps Section of GHQ, kept faith with Lieutenant Bragg and fought for him to get the resources he needed to continue his research. When, by the spring of 1917, Bragg had finally worked out how to account for weather conditions and wind direction, his sound ranging system could locate enemy guns to an accuracy of about fifty metres, good enough for the purpose of returning artillery fire.
Hundreds of sound rangers were eventually built before the end of the war, and sound ranging became the principal method for locating the enemy’s artillery after aerial observation. At Passchendaele in the summer of 1917 the sound rangers located 190 German guns in the first three weeks of the battle; at Cambrai they again correctly identified the sites of all the major pieces of German artillery, and at Vimy Ridge they successfully located a heavy howitzer that was hidden in a wood eleven miles behind
the front. By 1918 Bragg had moved on to teaching the principles of sound ranging technology to other young artillery officers many of whom were physicists and applied mathematicians, including Charles Darwin (grandson of the famous evolutionist), Edward Andrade and J.M. Nuttall. Bragg organised regular meetings for these officers to exchange ideas and reports on the use of the technology.
Bragg rose to the rank of major, and was awarded the MC for bravery and an OBE for his scientific work. He would go on to be one of the most distinguished scientists in Britain and was closely involved with the epoch-making discovery of DNA in the 1950s. Bragg, Robinson, Darwin and Nuttall were among the first British scientists in uniform, carrying out important scientific work on the battlefield, setting a precedent for much similar and vital work that would be done in the Second World War.5 And Bragg’s work in the artillery from 1915 to 1918 was a prime example of how academics came forward to bring their expertise to bear in the laboratory of war.
The Great War was dominated by the big guns of the artillery. However, when the British Army had gone to war in 1914 it was seriously under-gunned, both by comparison to its French allies and most especially to the German army. Every German army division at the start of the war possessed sixteen 150mm heavy howitzers; a British division possessed only four 60-pound guns by comparison.6 The Allies were stunned by the unexpected use of German heavy howitzers on the battlefield. The French did not like such heavy guns but put their faith instead in the 75mm quick-firing mobile field gun. The ‘75’ was light and highly manoeuvrable and was often described in 1914 as ‘the best field gun in the world’. It was known to the French themselves in sacred terms as ‘God the Father, God the Son and God the Holy Ghost’. Each French division had between forty and sixty of these guns.
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