by John Keegan
Not so at sea. Because of the ready availability of powerful electric current in turbine-propelled warships, radio communication within fleets and between their component units had become standard by 1914. There were difficulties; lack of directionality in contemporary transmitting sets made for interference, so intense in fleet actions that admirals continued to depend upon flag hoists to control their squadrons. Nevertheless, it had become clear by 1918 that the future of naval communications lay with radio.
Not, however, with radio telegraphy (R/T), as voice broadcasts were denoted to differentiate them from wireless telegraphy (W/T) in Morse code. R/T is insecure; the enemy overhearing it is as well informed as the intended recipient. Protection is possible, through very high-frequency (VHF) directional transmission, as in the Talk Between Ships (TBS) system used by anti-submarine escorts to great effect during the Battle of the Atlantic; but it is intrinsically short-range, as a secure means of speech. The only safe way of sending messages over long distance by radio wave is through encryption, effectively a return to W/T. Paradoxically, therefore, the flexibility and immediacy allowed by voice radio was denied both strategically and, except in limited circumstances, tactically, by its insecurity. While the control of naval warfare became, as the twentieth century drew on, increasingly electronic, through the rise of such derivatives of radio as radar, sonar and high-frequency direction-finding (HF/DF), high-level, long-range communication remained stuck at the level of wireless telegraphy, because of the need to encrypt or encode, the resulting message being sent by Morse.
That imposed delay, which was why, though the same imperatives should have applied to army and air force communications, soldiers and airmen, caught up in the dynamics of close-range combat when time was too short to encrypt or encode, broadcast freely by voice radio. Tactical codes were developed—the British army’s Slidex, for example—but even Slidex took time. In the cockpit of a single-seat fighter, any form of encryption was impossible. All armies and air forces therefore set up tactical overhearing services, called “Y” by the British, which listened in to the tactical voice radio transmissions of their opponents.13 Y frequently supplied battlefield intelligence of high value. During the Battle of Britain, for example, the British intercept stations were able to anticipate the warning of air raids supplied by the Home Chain radar stations by overhearing the chatter of Luftwaffe aircrew forming up before take-off on their French airfields.
Y was nevertheless of limited and local military value. Important radio communications were, from the First World War onwards, always encrypted or encoded, and only a combatant equipped to render secret writing into plain text could hope to do battle on equal terms with the enemy. The competence of the major powers varied, between themselves and also over time. In the forty-five-year struggle between the Germans and the British during the twentieth century, for example, the Germans unknowingly lost the security of their naval codes early during the First World War and did not regain it. The British, partly by capture and partly by intellectual effort, were able to reconstruct their enemy’s book codes in 1914 and thereafter to read high-level German communications at will. In the aftermath of the war, hubris—a repetitive influence on secret communication—led the British to believe their own book codes impenetrable, while the Germans during the 1930s both broke the British book codes, an intrinsically insecure means of secret writing, and adopted a machine cipher system, Enigma, which would resist the attack of its enemies’ cryptanalysts—Polish, French and British—until well into the course of the Second World War. The Polish success in breaking Enigma before 1939 was negated before the outbreak of war by German variation of their machine encryption.
There are other means of acquiring intelligence in real time besides seeing and hearing, notably through the indirect sight provided by photographic intelligence and, today, satellite surveillance; human intelligence—humint, or spying—can, in certain circumstances, also convey critically urgent information. Both, however, are prone to delay and defect. Images, however acquired, need interpretation; they are often ambiguous and can cause experts to disagree. Thus, for example, photographic evidence brought back to Britain from the German pilotless weapons development station at Peenemünde during 1943 did show both the V-2 rocket and the V-1 flying bomb. The weapons went unrecognised for some time, however, in the first case because the interpretation officers did not recognise the rocket in its upright, launching position, in the second because the image of the V-1 was so small—less than two millimetres across—that it was missed. Yet the pilotless weapon photographic evidence was comparatively clear and was supported by other intelligence which told the interpreters what it was that they should be seeking to identify. They knew they were looking for “rockets” and miniature aircraft; even so they failed to recognise the evidence before their own eyes. How much more difficult is image interpretation when the interpreters do not know exactly what the evidence will resemble when they see it: the hideouts of al-Qaeda terrorists, the bunkers of illegal Iraqi weapon development centres. The intelligence of imagery is frustratingly rich—many needles but in a vast haystack.
Human intelligence may suffer from different limitations: including, first, practical difficulty in communicating with base at effective speed; and, second, inability to convince base of the importance of the information sent. The world of human intelligence is so wrapped about with myth that any clear judgement about its usefulness is difficult to establish. It does seem, that, for example, the Israeli foreign intelligence service was running an “agent in place” at a high level in Egypt before that country’s attack on Israel in 1973. Because the Egyptian government dithered over the decision to attack, the agent sent a succession of self-cancelling reports, with the result that, when the attack came, the Israeli army had gone off high alert. True or not, the story leaves unresolved the question of how the agent was able to communicate in real time. The case of Richard Sorge was entirely different; he was both highly placed and well equipped to communicate by clandestine radio. His difficulty—of which he was unaware—was to secure a hearing. Sorge, a committed Communist and long-term Comintern agent, had established himself before the Second World War in Tokyo as the respected correspondent of a German newspaper. As a German native and citizen thought to be entirely patriotic, he became intimate with the staff of the German embassy, passed on information about Japanese affairs the diplomats found useful and eventually began to assist the ambassador in drafting his reports to Berlin. As a result, he was able to send the assurance to Moscow, during the terrible summer of 1941, that Japan did not intend to assist its German ally by attacking the Soviet Union through Siberia. He had earlier sent convincing warning of Germany’s intention to invade and had even identified the correct date, 22 June. Stalin had received other warnings, including one from Churchill, but chose to ignore them, as he ignored that of Sorge. The idea of war was too uncomfortable; Stalin preferred to believe that he could buy Germany off by fulfilling delivery of strategic materials, including oil. As to the assurance that Japan would not invade Siberia, the evidence is that Stalin had moved a large portion of the Soviet garrison out of Siberia before the attack of 22 June and that Sorge’s warning, even if heeded, was not the critical strategic intelligence it seemed to be.14
Other celebrated human intelligence organisations of the Second World War, the “Red Orchestra” in Germany and the “Lucy Ring” in Switzerland, also lack credibility as media of real-time intelligence, though for different reasons. Sorge is almost unique among identified operators in the world of humint by reason of his undoubted access to information of high quality and his ability to forward it speedily to base. The Red Orchestra, a coterie of left-inclined Germans of superior social standing, was a dilettante organisation led by a Luftwaffe officer with a double-barrelled name, who seems to have been animated by the excitement of misbehaviour. They transmitted little of importance to Moscow, betrayed themselves by lack of elementary security precautions and were rapidly rolled up by
the Gestapo. The information supplied by the Lucy Ring—in reality an individual called Rudolf Roessler—to Moscow from Switzerland during the war seems to have been derived largely from his study of the German press. The rest was fed to him by the Swiss, who maintained contacts with the German Abwehr. The Swiss feared that a German victory would lead to the incorporation of their country into a greater Reich; the Abwehr was adept at playing a double, if impenetrable, game. Roessler may have belonged to that colourful gang of fantasists who enriched themselves, at the expense of the secret service budgets of many countries, throughout the Second World War.15 In any case, he lacked a radio link to Moscow.
The ability to communicate, quickly and securely, is at the heart of real-time intelligence practice. It is rarely enjoyed by the agent, that man of mystery who figures so centrally in the fictional literature of espionage. Real agents are at their most vulnerable when they attempt—by dead letter box, microdot insertions in seemingly innocent correspondence, meetings with couriers, most of all by radio transmitter—to reach their spymasters. The biographies of real agents are ultimately almost always a story of betrayal by communication failure. A high proportion of the Special Operation Executive (SOE) agents in France during the Second World War were discovered by German radio counter-intelligence; the same was true of those operating in Belgium while, as has become well known, at one stage all agents dropped into Holland were collected on site by German manipulators of the SOE radio network. Even when counter-intelligence is deplorably lax, as in the notorious “Missing Diplomats” case, the certainty of Donald Maclean’s guilt was finally established, even if retrospectively, by his habit of leaving Washington to meet his Soviet controller in New York twice a week.16
It is the intrinsic difficulty of communication, even, indeed above all, for the agent with “access,” which limits his—or occasionally her—usefulness in real time. By contrast, the enemy’s own encrypted communications, if they can quickly be broken, will, of their nature, provide intelligence of high quality in real time.
The history of “how, what, where, when” in military intelligence is therefore largely one of signal intelligence. Not exclusively; human intelligence has played its part, and so, latterly, have photographic and surveillance intelligence. In principle, however, it is the unsuspected overhearing of the enemy’s own signals which have revealed his intentions and capabilities to his opponent and so allowed countermeasures to be taken in time.
The case studies that follow will support this argument. Not, however, in its entirety; one case study, that of the German airborne descent on Crete in May 1941, has deliberately been chosen to demonstrate that even the best intelligence will not avail if the defence is too weak to profit by it. Other studies—particularly those of the Battle of the Atlantic and the V-weapons—emphasise the parallel importance of non-intelligence factors, in the first case, and of photographic intelligence and humint, in the second, in defeating the threat. The book begins with studies of intelligence campaigns in the age before signal intelligence was available to a keen-eared listener. The examples of Nelson’s Mediterranean campaign of 1798 and Stonewall Jackson’s campaign in the Shenandoah Valley in 1862 may persuade those who expect too much—or too little—of modern intelligence-gatherers and -users to reconsider their opinions.
It has become part of the conventional wisdom that intelligence is the necessary key to success in military operations. A wise opinion would be that intelligence, while generally necessary, is not a sufficient means to victory. Decision in war is always the result of a fight, and in combat willpower always counts for more than foreknowledge. Let those who disagree show otherwise.
CHAPTER TWO
Chasing Napoleon
ACCURATE INTELLIGENCE in the age of sail was a scarce commodity. Accurate intelligence is, of course, scarce at all times, but the sea, in the years before radar and radio, let alone satellite surveillance, was an arena of the unknown. The horizon was an impenetrable barrier, the man-of-war, breasting the waves at six knots or so, a ponderous means of extending a captain’s field of vision beyond it. An admiral with a fleet under command could enlarge his supervision by disposing his men-of-war and their attendant frigates at intervals of a dozen miles or so, the maximum distance at which intervisibility and so intercommunication, masthead to masthead, was possible. Even thus, the transmission of news of a sighting was a haphazard business. Admiral Lord Howe, seeking to establish the whereabouts of a French convoy of 139 merchantmen he knew to be nearby, had to quarter the sea for eight days before he brought its escort to action on the Glorious First of June 1794. The interception was rightly regarded as remarkable. The battle took place 400 miles from land at a time when most sea engagements were fought, as they always had been, within fifty miles of the coast.
Admirals, moreover, did not like to disperse their capital ships for purposes of reconnaissance, needing to keep them concentrated for action lest the enemy were met unexpectedly. The need to gather information always had to be balanced against that of keeping firepower massed under the commander’s hand. The strength of a fleet lay not in that of its individual units but in the line of battle, formed bow to stern at intervals of a few hundred feet. Ships isolated were ships exposed to “defeat in detail,” or one by one, by superior numbers. Hence the importance of the capital ships’ scouts, the frigates, smaller and swifter sailers which could be sent to and beyond the horizon in search of the enemy.
No admiral ever had enough frigates. The calls on their service were manifold: as despatch vessels, as commerce raiders, as convoy escorts. Such duties chronically depleted the number available as scouts and “repeater ships,” which lay close to but outside the line of battle, copying the signals of the flagship, which were often masked by its near neighbours, so that they were visible from van to rear. The scarcity of frigates was odd. As they were much smaller than battleships, a third or a quarter by displacement, carried far fewer men, perhaps only 150 against 800, and cost only a fifth as much to build, it might be expected that they would have been turned out in much larger numbers. Such was not in practice the case. In 1793, at the start of the Wars of the French Revolution, the Royal Navy had 141 first- second- and third-rates, battleships with between 100 and 74 guns; of fifth- and sixth-rates, frigates of between 44 and 20 guns, it had only 145;1 by 1798, there were still only 200. Little wonder Nelson, then the Mediterranean admiral, warned that, if he died, “want of frigates would be found written on his heart.”
Essential though frigates were as scouts, their value was restricted by the limitations of the signal system then in use. It was not simply that flags—and flags were the principal means of communication—were difficult to discern at long distance, even with a telescope. No comprehensive system of arranging them to transmit information had yet been devised. Various conventions had been in use since the seventeenth century, such as then, for example, hoisting a red flag at the mizzen-top to order a particular manoeuvre. By the late eighteenth century there had been a great deal of elaboration and in 1782 Admiral Howe, then in command of the Channel Fleet, had issued a codebook, superseding many others, which allowed a commander to say 999 different things with three flags and 9,999 with four. Howe’s signal book was not, however, double-entry. The recipient could work out what a signal meant by looking it up, finding the flags picture by picture on the page. The sender, however, had to know what flags he needed to hoist before he composed his message. Not until 1801, when Home Popham published his Telegraphic Signals or Marine Vocabulary, were sender and recipient put on equal footing. Popham, a sailor of great clarity of mind, simply had a flash of insight into the obvious which had evaded thousands of other sea officers before him. His achievement compares with that of his near contemporary Roget in compiling the first thesaurus. He analysed how language was used and saw that words might be given a numerical value, to be signalled by a set of numerical flags; 212, for example, could be made to stand for “cable,” with the numerical flags 2, 1 and 2. Adding a fo
urth numerical flag, 3, made the signal read “Can you spare a cable?” To make the first signal, the sender looked up “cable” in his double-entry book and chose the appropriate set of flags or “hoist”; to read it, the recipient looked up 2123 and got the message.2 By the use of special indicators it could also be signified that flags had alphabetical rather than numerical value and should be read simply as letters, spelling out an unusual word not in the vocabulary. Popham’s final signal book allowed 267,720 signals to be made with twenty-four flags (of which ten doubled as numbers) and 11 special indicators.
His system remains in use to this day. It was not yet so in 1798, when the Royal Navy still sought to speak fluently between ships through the medium of Admiral Howe’s single-entry book. A great deal of time was wasted, therefore, in frigates closing up to each other or to the main body in order to transmit information unambiguously or to receive precise questions or clear orders. The days when a flag lieutenant could snap his telescope shut and confidently interpret to his superior the meaning of a flash of coloured bunting glimpsed at the extreme limit of visibility on a clear Mediterranean day lay well in the future.
The fallibility of signalling was not a crucial factor in the conduct of maritime operations in the last decade of the eighteenth century. It counted for much less than want of frigates. It counted as a factor, nonetheless, particularly to an admiral like Horatio Nelson, whose mind never rested, who calculated the relative positions of ships and shorelines as a master chess player does pieces and squares, who consumed information of every sort with the compulsion of an addict, who sought decision in battle with the relentlessness of a great financier poised to obliterate his commercial competitors. Home Popham’s signalling system certainly would have assisted him in his searches had it been available; when it became so a very few years later, Nelson enthusiastically embraced it; indeed, the most famous flag signal sent, “England Expects,” was made at the opening of the Battle of Trafalgar on 21 October 1805, with eight Popham hoists and “Duty” spelt out alphabetically.