(This article first appeared in Stand To! 28 Spring 1990 pp7-11)

As some of you will know, but others may not, the book that I have been working on for the last four years came out in September. Its title is Business in Great Waters, from Psalm 107 (the Seamen's psalm), which tells us:

They go down to the sea in ships, that do business in great waters; These see the works of the Lord, and His wonders in the deep.

My sub-title is 'The U-Boat Wars, 1916-1945', and if that subject does not display to us 'wonders of the deep', I don't know what does. I thought you might like to hear something about it today.

Let me admit, straight away, that it is not quite the book I intended to write. I set out to write a history of the Battle of the Atlantic in World War II. And why not? It was, after all, unique—nothing like it, nor likely again.

According to the German authority, Dr Jurgen Rohwer, it was, among other things: 'the longest battle of the Second World War. It began on September 3 1939 and ended on May 8 1945.' Our own official naval historian, Captain Stephen Roskill, says: 'In all the long history of sea warfare there has been no parallel to this battle, whose field was thousands of square miles of ocean, and to which no limits of time or space could be set.' Winston Churchill called it: 'the dominating factor all through the war', and elsewhere he said that it was 'the only thing that ever really frightened me.' So I think we may safely say that it is a subject worth study. The Battle of the Atlantic was undoubtedly a decisive battle of World War II.

But I quickly discovered—as I have done before—that much of World War II is only intelligible in the light of World War I, and the Atlantic battle was definitely in this category.

It must be over ten years ago now that I perceived with clarity that the only reliable clue to the two great wars of this century— that is to say, the two great wars of the period of the First Industrial Revolution—is technology. And it is a simple fact that the two U-boat wars belonged to the same bracket of technology: they used the same sort of machines, the same sort of weapons, and much the same techniques. They belonged together. To write about the Second U-boat war without the First would be like writing a man's biography starting when he is about 30.

And 1916 seemed to be the right place to begin—though some would dispute it— because that was when the Germans began to make a regular practice of what was then known as 'unrestricted submarine warfare', although they did not formally declare that fact until February 1917. And the Battle of the Atlantic was, of course, unrestricted warfare' from the very first until the bitter end.

It was Mr Arthur Balfour, ex-Prime Minister, who raised the question in May 1913 with his old friend, Admiral of the Fleet Lord Fisher, whether submarines might not make Britain's position as an island power, depending on trade, 'untenable'.

Thus prompted, that remarkable man 'Jackie' Fisher responded with an official paper to the First Lord of the Admiralty, Winston Churchill, in June 1913, in which he argued, in effect, that there could be no other form of submarine warfare than 'unrestricted'. The submarine, he said:

cannot capture the merchant ship; she has no spare hands to put a prize crew on board; . . . she cannot convoy her into harbour . . . There is nothing else the submarine can do except sink her capture, and it must therefore be admitted that this . . . submarine menace is a truly terrible one for British commerce and Great Britain alike, for no means can be suggested at present for meeting it except by reprisals . . .

And Fisher concluded that prediction with the ominous and also prophetic words: 'the essence of war is violence, and moderation in war is imbecility.'

Neither Churchill nor the First Sea Lord, Prince Louis of Battenberg, could bring himself to believe Fisher's prophecy. No civilised power, they said, would adopt such methods and this was also the consensus of opinion in the Admiralty. I would also go so far as to say that it was a consensus opinion in the German Admiralty too. When the Germans went to war a year later, they really didn't know what they were to use their submarines — the U-boats, U nterseeboote—for; if pressed, they would most likely have answered in all honesty 'to attack the enemy's battle fleet'.

The U-boats themselves, however, soon proved Admiral Fisher's point. For a couple of months U-boat warfare was indeed waged against naval vessels, the first sinking being the British light cruiser P athfinder on 3 September 1914. Just over a fortnight later, on 22 September, Leutnant Otto Weddigen in U9 performed the famous feat of sinking three elderly British cruisers one after another—Hogue, A bou kir and Cressy—in a space of about an hour, during which nearly 1400 officers and men of the Royal Navy lost their lives, over three times as many as the British fleet at Trafalgar. It was a shocking blow to a navy which had taken absolute supremacy for granted for over a hundred years.

However, even more important than this drama was an outwardly much smaller event a month later. This was the first sinking of the little British freighter Glitra by U 17 on 20 October—the first merchantman to be sunk by a submarine in war.

And less than a week later came another of those quickly succeeding milestones of 1914—the sinking of the French passenger steamer Amira  Ganteaume by Korvettenkapitan Schneider's U24 at sight, without any warning, killing about forty people, on 26 October. Schneider thus became the first practitioner of 'unrestricted U-boat warfare', and as such deserves a place in history for better or worse. And strictly speaking this should be where our story begins. The thread between Schneider's performance and Leutnant Julias Lemp's U 30 at 1400 hours on 3 September 1939, when the U-boat sunk the liner A thenia equally without warning, at a cost of 112 lives (twenty-eight of them American) is continuous—though somewhat indirect.

In November 1914 both sides were practising the ancient art of blockade, but in the modern fashion: distant blockade by the Royal Navy, and submarine blockade by the Germans. The British got their declaration in first, which enabled the German Naval C-in-C to say: 'The gravity of the situation demands that we should free ourselves from all scruples . . . ' It was easier said than done; there were two main objections to being completely unscrupulous: first, the adverse political effect on neutrals (especially the USA), and secondly, the lack of means.

Both wars began and for a long time continued—though many in Britain would have found this hard to believe—with what Admiral Donitz in 1939 called 'a dearth of U-boats'. From September to December 1914, there were rarely more than three at sea in British waters simultaneously at any time. From August 1914 to December 1916—nearly 2Vi years—there were never more than seventeen; it was not, in fact, until July 1916 that that figure was reached— which is another good reason for treating 1916 as the real beginning of unrestricted submarine warfare.

It was coming all right, but it didn't just happen at the stroke of someone's pen or on a precise order. It was something that the Uboat captains adopted because the nature of their trade impelled them to. In 1915 21% of sinkings by U-boats were carried out without warning; in 1916 the figure was 29%; by May 1917 it was 64% and the proportion rose steadily month by month; by 1918 it was the normal method—and if Leutnant Lemp did nothing else, he demonstrated that this was still the case in September 1939.

What was also the case in 1939 was that there were not many U-boats. A far-sighted German officer stated, before 1914, that for an effective blockade of the British Isles, 222 U-boats would be needed (marvellous to be so exact!). In fact, never at any time in World War I did Germany have more than 140 in commission, and that figure was not reached until October 1917.

It was not reached again until July 1942, although Donitz had said in early 1939 that he would need 300. When war broke out he had forty-two operational and the highest number he ever reached was 239 in May 1943.

To Merchant seamen who had to run the gauntlet, and sailors who had to fight them, U-boats seemed to be swarming everywhere. Airmen probably had a different idea—they had, after all, a much better view of the empty vastness of the sea. But all would have been amazed—indeed, incredulous—if they had been told how few the enemies were who were doing so much damage in both wars.

I think we had better remind ourselves at this juncture of what the damage was. And I fear that, like just about every other feature of the U-boat wars, this can only be expressed in statistics. Not for nothing did Churchill say of the Atlantic battle: 'How willingly would I have exchanged a full-scale attempt at invasion for this shapeless, measureless peril, expressed in charts, curves and statistics!'

Taking July 1916 as our starting point for unrestricted warfare, in the next six months it had caused the loss of over lVz million gross registered tons of Allied shipping. The worst year by far was 1917, with a total of over 6 V2 million tons, including the terrible month of April when 881,027 tons were lost. For the whole war the total sunk by submarines was more than 1 1 million tons.

The shock—to the fairly limited number of people in high places who knew what was happening—was naturally tremendous.

And 1942 was another year in the same mould: no fewer than 1664 ships went down—a total of almost 8 million tons, and of those fearsome totals submarines accounted for 1160 of the ships and over 6 V4 million tons. I always think that with numbers like these you just have to settle for the look, or the sound of them. I don't think anyone can form an exact image of a million of anything, and certainly not of a million tons of shipping. Even a thousand ships— or a thousand aircraft—are really beyond us. But there is one further thing to be said about 1942, to try to take its measure. No month during it—or during World War II— ever matched the staggering 881,027 tons lost in April 1917: but three times in 1942 (and never again), in March, June and November, the total went above 800,000.

And this was still not the climax of the Battle of the Atlantic.

That came in March 1943, when the first ten days saw forty-one ships go down and the next ten days saw fifty-six—more than half a million tons of shipping lost in twenty days. Looking back on that period a bit later, the Admiralty stated: '. . . the Germans never came so near disrupting communication between the New World and the Old as in the first twenty days of March 1943.' The Naval Staff dotted the 'I's and crossed the 'T's of that: 'It appeared possible that we should not be able to continue [to regard] convoy as an effective system of defence.' And if that thought was not devastating, I don't know what is, because as Captain Roskill says: 'Where could the Admiralty turn if the convoy system had lost its effectiveness? They did not know; but they must have felt, though no one admitted it, that defeat stared them in the face.'

Well, I am now running somewhat ahead of myself, but I hope I have said enough to show the pattern of striking similarity between the two wars and a clear continuity. This is not to be wondered at, because as I said at the beginning, they belong unmistakably to the same bracket of technology. The fact is that neither of the two U-boat wars, including the whole of the Battle of the Atlantic, was really a submarine war; all the way from 1914 to the end of 1944, U-boats were submersibles—torpedo boats whose best performance of range and speed were on the surface, but which had the ability to dive for attack or escape. Only in 1942 did a change come about—I shall refer to it later—and only in 1945 was a brief glimpse seen of vessels bordering on true submarines.

In both the World Wars the U-boats were powered by diesels on the surface, and electric motors when submerged. This was what made them submersibles; after a few hours underwater movement they would have to come to the surface to recharge their batteries. So in both wars these were the moments for anti-submarine forces to wait for—the times when the U-boats lost what Donitz called 'their most valuable attribute—invisibility'.

I said 'torpedo boats' just now. In both wars, somewhat reluctantly because guns could often have done the job just as well and more conveniently, the Germans quickly accepted that the U-boat's prime weapon was and would remain the torpedo. Twice in World War II they faced crises when their torpedoes developed alarming defects—in 1940, during the Norwegian campaign, it was so bad that Donitz had to pull them out altogether; in 1943 it was also bad for a time, but a remedy was soon at hand.

Whether working properly or not, torpedoes were of the essence of U-boat warfare, and they are what gave it its bad name. Attack by torpedo was stealthy, unexpected, sudden, devastating—and inevitably, at the receiving end, looked 'unfair'. Attack with gunfire was something you could see, something well established down centuries of naval warfare, and something you might counter with guns of your own—which was, of course, precisely why the U-boats took to their torpedoes.

And now what of the anti-submarine forces? In 1914 there were none, and as regards purpose-built vessels, this remained substantially true throughout the First World War. The Royal Navy mainly used two types of ship, greatly contrasting: the fishing boats (mainly trawlers) of what was called the 'Auxiliary Patrol', 3000 of them, and destroyers.

By November 1918, the Royal Navy had 443 destroyers in commission. They had been the mainstay of the anti-submarine effort from first to last—a task for which they were never intended. The essence of a destroyer was speed; one of the very earliest, HMS Viper, in 1899, could attain a maximum of thirty-seven knots and could hold thirty-nine knots for three hours. As Churchill once said: 'Building slow destroyers! One might as well breed slow race horses.' To achieve their high speeds they needed massive engine-power and hulls built to accommodate it. The average building time for a destroyer in 1939 was eighteen months—and they were expensive items, becoming more so, of course, as time went by.

The contrast of these sleek 'greyhounds of the sea' (as journalists called them) and their U-boat enemies, with best speeds of sixteen and seventeen knots, was startling. The contrast with the merchant ships they were now expected to protect, rarely doing more than ten knots and often struggling to maintain five, was even more so. Was it worth it?

It has always been a tradition, in the Royal Navy, to go for the enemy and hit him as hard as possible and as soon as possible. Faced with this new foe, the Navy's reaction was immediately to take the offensive, to attack, and for that, speed could never be a bad thing. In both wars, the Admiralty showed a faithful but regrettable predilection for what it called 'hunting groups', and these resolutely set out to carry the war to the Uboats. Since, however, the U-boats persisted in making full use of their asset of invisibility, what this mainly achieved was a prodigious waste of destroyer time and seamen's patience. The truth is that there was only one way of making sure of finding U-boats (which I shall shortly discuss). This became quite apparent between 1917-18, but like so much else it was soon forgotten or thrust aside, and in 1939 the Admiralty astonishingly stated its intention of forming nineteen hunting groups, each of five ships and some reconnaissance aircraft, to patrol and protect British waters against submarines. Since it had only 101 destroyers available for these duties, that would effectively have taken care of the whole of its most important anti-submarine force. But circumstances—and U-boats—dictated that it should be otherwise.

You will note my mention of reconnaissance aircraft—a new feature. I don't mean that aircraft were new to antisubmarine warfare in 1939—far from it. It was in 1917 that the seaplane, the flying boat and airships of the Royal Naval Air Service became an essential part of the antisubmarine scene—a highly significant extension of naval warfare. The RNAS was not, I fear, a lot of help to the 'hunting groups', despite its much greater range of vision, but it is a fact that the one solitary U-boat kill between 1914-18 now confirmed as being by an aircraft was, I believe, performed by a patrolling flying boat, using a patrol system known as the 'spider web' which was effectively revived by Coastal Command in 1944 for the protection of the 'Overlord' convoys.

If and when the hunting patrols or other naval vessels did encounter a U-boat, it became steadily apparent that the prime weapon for its destruction was the depth charge. This was first thought of in 1911, but like much else it was a slow comer through the stages of development and production. At the beginning of 1917 the depth charge equipment of a destroyer was precisely two charges—which is really pathetic. A year later, however, it was thirty-five charges— as in World War II—and in 1918 more Uboats were sunk by depth charges than by any other weapon.

As one might suppose, the depth charge very quickly reasserted its position in 1939 and at the height of the Battle of the Atlantic depth charge consumption became enormous. Captain F. J. Walker's famous 2nd Escort Group probably carried depth charge tactics to their zenith—once firmly held by Walker's Group a U-boat had very poor chances of survival. The Group's most brilliant action was in February 1944, lasting twenty days during which six U-boats were destroyed and no fewer than 634 depth charges were fired off. Another action at about that time involved a chase lasting thirty eight hours—the longest on record— and depth charge attacks which caused what was described as a 'marine convulsion'. The U-boat (U358) was brilliantly handled, but finally forced up by the depth charges and finished off by gunfire at 1500 yards; she managed to take the frigate G ould with her—a good example of the blow-for-blow quality of this battle. It was an example also of the ability of U-boats to dive and survive at great depths which amazed all observers in both wars. In 1943 we learn of a Type VII U-boat which survived fierce depth charge attacks for thirty-five hours during which it went down to 200 metres below the surface—that is 915.6 feet. I think it is a miracle that the whole crew did not go stark staring mad.

And there was something else about depth charges—a most significant development marking a big contrast between the two wars. For the first two years of World War II the sad condition of Coastal Command was, in the words of the historian Denis Richards, 'Our aircraft could seek, find, report, strike and wound. They could not yet kill.' In a nutshell, Coastal Command lacked a lethal weapon: the anti-submarine bombs on which the Air Ministry and Admiralty pinned their faith—despite the teaching of 1917—proved useless, and the naval depth charge was liable to be as lethal to the aircraft dropping it as to the intended target. But in August 1941 real airborne depth charges began to trickle in, and then it was just a matter of discovering, by trial and error, how they should be used. By 1943 it was firmly established, as Sir John Slessor observed when he became AOC-in-C, Coastal Command, that: 'the decisive weapon of the anti-submarine squadrons was the Mark XI torpex-filled depth charge, dropped in sticks of four to eight from point blank altitude, fifty to a hundred and fifty feet.'

The great problem, throughout both wars, was that no method of accurately determining the depth of a submerged U-boat was ever found. Operational research indicated that the closer the stick of depth charges came to the diving whirl of the U-boat, the better the chance of sinking it, so for visual air attacks a very shallow setting was preferred—25 feet, in fact.

Coastal Command used other weapons too—rockets, 57 mm anti-tank guns, acoustic homing torpedoes (known as Mark 24 Mines) which were sometimes effective, and in June 1943 there were once more experiments with a big, streamlined fast diving 6001b anti-submarine bomb. But the standard 300 lbs depth charge remained to the end the main weapon both for ships and anti-submarine aircraft.

Weapons and systems, as I have suggested, are not much good without targets—a blinding glimpse of what I often call the 'great simplicities' of war. So whatever weapon it was intended to use against the U-boat, the first thing that had to be done was to find it. In both wars the $64,000 question was (with suitable embroideries): 'Where is he?'

If he was on the surface, as he might well be, obviously an aircraft had a better chance of seeing him than a ship. This air role has been aptly called 'the Eye in the Sky'. And it was matched from the very outbreak of World War I by what we may call 'the Eye in the Ether'—the interception of radio signals which, as I believe Sir Winston Churchill said of 1914-18, 'made it impossible for the Germans to move a picket boat in harbour without the British Admiralty knowing about it.'

The Germans suffered a heavy Intelligence defeat in World War I, when all three of their operative naval codes were captured by the Allies. This meant an insight into their plans and movements which had to be won in World War II by a major effort in difficult cryptography on the part of the Government Code and Cipher School at Bletchley Park, and the highly secret system of Intelligence dissemination known as ULTRA.

But even without this penetration of the messages of the signals, there was another valuable product of radio-interception: direction-finding. Already by May 1915 it was possible to track the progress of a U-boat across the North Sea by D/F. By 1942 it was possible to track them across the Atlantic, thanks to a chain of D/F stations starting in Devon, running up the west coast of Britain to the north of Scotland, out to Iceland and Greenland, via Newfoundland, Nova Scotia and the American coast to the West Indies. It is hardly possible to exaggerate the importance of the vigilant and precise watch maintained on a vast theatre of war by these stations.

But if the U-boat was not on the surface something more was needed, and it was the fate of the World War I generation to encounter for the first time (as in so many things) the little matter of exploring the ocean deeps in search of the enemy. The first device they came up with was the hydrophone, Directional and Non-directional, of which eleven types were produced during World War I. The purpose of the hydrophone was to detect and if possible follow the sound of a submerged U-boat in motion. Its weakness was its vulnerability to interference by other sounds—the general turbulence of the sea, or the engine of the ship carrying it, or the noise of the ship passing through the water—or the silence of an immobile U-boat. An attempt to use hydrophones suspended from aircraft was, needless to say, unsuccessful. They were not the final answer, but they were a good one, and they continued to be used right through World War II, not least by the U-boats themselves, who were able to pick up the sound of convoys at ranges of 50 miles or more.

World War II leaned on other methods, two of them developments from the earlier war, one of them brand new. D/F gained a new dimension: HF/DF (High Frequency Direction Finding; often known as 'HuffDuff'). The great breakthrough on this front came in 1942 (a year of decisive happenings) when the installation of the FH3 receiving equipment in ships made possible the simultaneous translation of a U-boat signal which might be no longer than a single 15 second 'bleep' into a spot of light on a screen which would remain there long enough for an accurate fix which spelt the early death of many a U-boat. HF/DF was one of the undoubted battle-winners.

The second profoundly important development was the steady improvement between the wars on the work of a committee set up in June 1917: the Allied Submarine Detection Investigation Committee, whose initial letters spell out ASDIC. This was the then familiar name of what is now called 'Sonar'. The essence of ASDIC was the reflected sound of a beam projected through water. It had the great advantage that it could be operated from ships moving at fifteen knots or more and was a vastly more precise locator than any hydrophone. The disadvantages were, first, that many other objects than submarines could reflect the beam (wrecks and rocks being perhaps the most pernicious), and this was something only a highly-skilled operator could deal with. Secondly, and this was something that nobody could deal with, ASDIC was useless against a submarine on the surface.

This was a pity, because by 1918 surface attacks by night had become normal U-boat tactics (in the Mediterranean 67% of all attacks were carried out in that manner). ASDIC appeared just too late to be operational in 1918, but such was the extraordinary — you could say, superstitious—faith that the Admiralty placed in this new weapon that in 1937 the Naval Staff pronounced categorically that: 'the submarine should never again be able to present us with the problem we were faced with in 1917.'

The U-boats, under the remarkable guiding hand of Admiral Donitz, made no such error, so it rapidly became apparent that something fresh was badly needed to counter them. The 'something fresh' was one of the very few real technical innovations of World War II: radar. By this I mean radar in its naval and maritime air role, whose early development suffered from competition with the urgently needed Air Defence role which stood us in such good stead in 1940. But by 1941 seaborne radar was operative and effective (though production was always well behind demand) and in that year airborne radar for anti-submarine warfare received the promise of enormous aid from the new centimetric version known as ASV ('Air-to-Surface-Vessel') Mark III. Unfortunately the advent of this exceedingly valuable search instrument led to a bitter clash between Coastal and Bomber Commands. Sir Arthur Harris at Bomber Command demanded first use of the new radar as a bombing aid, under the designation of H2S, and even in the sea crisis of 1942 Harris was able to win this one. But when Coastal Command did at last receive ASV III in reasonable quantities to support the Navy's centimetric radar and HF/DF, the threat to the U-boat's priceless asset of invisibility, both by night and day, on or below the surface, became real and soon decisive.

So much for weapons—a quick skim over the surface of a vast subject which was, like the equipment of the air forces in both wars, of absolutely fundamental importance. The work of the technical Services is unintelligible without constant reference to the technology at their disposal. In World War II we were rapidly approaching the point where all Services are technical.

I come now to the two outstanding differences in anti-submarine warfare between 1918 and 1940. Convoy was a wellestablished British method of efficient tradeprotection, dating back to the Seventeenth Century, but which had languished in the age of steam. It was reintroduced with some trepidation and not unreasonable doubt in May 1917, and very soon proved its continuing effectiveness. To give just one example, on the North Atlantic routes in the period to the end of November, out of 1815 vessels convoyed, only fourteen were lost—a rate of .77%. Even more striking is the fact that out of the whole number of ships convoyed between May 1917 and November 1918, only two were lost from convoys which had air as well as naval escort.

However, prejudices against the convoy system, based on its supposed purely 'defensive' quality, died hard. Not until 1937, when things were hotting up in unmistakable fashion, was it agreed that convoys would have to be reintroduced in the event of war. This was, thank Heaven! in time for a great deal of valuable planning and preparation to be done. But there was a lamentable and apparently deliberate disregard of past experience which ignored the statistical evidence of convoy as a means of actually sinking U-boats (compared with 'hunting groups'), and also, worse still! of the air escort role, which had been brought to a high level of exactitude in 1918. This accounts in large part for the lost look of Coastal Command when war broke out, its slow introduction to anti-submarine warfare and its even slower achievement of real effectiveness.

All this may now seem extraordinary. And it draws us to another matter which was vital in the Atlantic Battle. I think I can do no better than to quote here the words of the Royal Navy's great American historian, Professor A. J. Marder:

The Admiralty did not understand that an increase in convoys meant an increase in opportunities to attack U-boats, and therefore more U-boats destroyed; nor that if it was a fine thing to dispose of a U-boat, it was even better to keep them down and thus bring the convoy to harbour without loss. In other words, the merits of convoy can be argued cogently without the question of sinking submarines ever coming into it. Sinking submarines is a bonus, not a necessity. The only necessity in war is to stop submarines sinking ships.

Nothing concentrates the mind so swiftly as the pressure of war itself. Before convoy battles were a year old, in April 1941, Western Approaches Command issued its famous Convoy Instructions to Senior Officers of Escorts: 'The safe and timely arrival of the convoy at its destination is the primary object, and nothing releases the Escort Commander of his responsibility in this respect.'

From the air point of view, Marder's analysis is comforting. All through World War I and right up to mid-1942, the antisubmarine role of aircraft was what was halfcontemptuously known as 'Scarecrow'. Why this should have been despised I cannot think; the purpose of a scarecrow is to save a crop; if it does that it is 100% effective. Aircraft, by their very presence, between 1917-1942 saved uncounted ships and cargoes, and that should be the measure of their effectiveness.

Yet a modification of Marder's pronouncement has to be made, dictated by a fundamental change in the nature of the Battle of the Atlantic which came about in 1942. So now is the time to take a quick look at the nature of that battle.

We have first to seize upon the fact that, despite a feeble attempt in 1918 (lacking the requisite communications equipment), and some half-cock efforts in the early days of World War II (lacking enough U-boats), effective attacks on convoys did not begin until late 1940. This is not surprising, since the Battle of the Atlantic itself did not properly begin until the second half of that year.

The reason for that is strictly geographical. Germany herself is ill-placed for sea warfare; the Baltic and the German North Sea ports have only one practical access to the Atlantic—northabout, through the waters between Scotland and Iceland. It is a long haul, under close sea and air surveillance all the way. But in June 1940 this disadvantage was wiped out at a stroke: the fall of France gave Germany direct access to the Atlantic and gave the U-boats a starting-point towards the trade routes virtually as far west as the south-western tip of England. This meant in 1940 that they could operate as far out as 25 °W, whereas surface escort operated only as far as 17°, and only flying boats could operate beyond 15°. Small wonder if the competent peace-trained Uboat commanders who were soon known as the aces' enjoyed the first of their 'happy times'; small wonder if this period was called by one historian who fought through it, 'the very nadir of British fortunes' in the battle. It was in September that pack attacks (albeit weak in numbers) began, and the same officer described October, when three convoys lost thirty-eight ships between them, as 'catastrophic'.

So it was, and for a long time so it remained—a catastrophe enhanced by the sheer lack of escort vessels and aircraft, the lack of appropriate weapons and equipment, perhaps above all the lack of training and thought-out doctrine.

It was often bad again, but never so bad. The continuing feature of the battle was its steady move westward, and this was a result above all of air power. It was soon seen that, as in World War I, the U-boats could not bear the sight of aircraft. It seems strange when one considers how ill-equipped all aircraft were in 1939-40 for attacking U-boats but it was a fact that when aircraft were present they broke off their attacks, and when aircraft departed they closed in again. So the Battle of the Atlantic shifted steadily westward, and when aircraft joined in from Iceland and Canada, the danger area was narrowed to a trifling 600-700 miles of misery known as 'the Gap' where aircraft could not reach. And so a sub-battle developed between Coastal Command and Western Approaches on one side, and Bomber Command and the Air Ministry on the other, to obtain the invaluable VLR (Very Long Range) machines which could operate in 'the Gap'. What this meant in brass tacks was a battle for use of the superb but scarce Consolidated B-24 Mark I Liberators, remodified for this task. When they finally became available in 1943, it was wonderful how few proved to be needed to tip the scale.

Nineteen Forty One was a year of home truths; it was also a year of most rewarding success on the Intelligence front, when the GC&CS at Bletchley Park broke the German naval cipher HYDRA. This made Siging decrypts a prime weapon in the armoury of the Admiralty's Operational Intelligence Centre, lodged in that hideous pink bunker on the Horse Guards Parade, and in particular that priceless piece of antisubmarine war-making apparatus, the Submarine Tracking Room, under its brilliant chief, Commander Rodger Winn, RNVR. Winn has been called the true opponent of Admiral Donitz in this very special war; I am not sure that modem war breaks down into such personal combats, but if you do adopt the chess-board image it is hard to see who else would be sitting on our side of it.

Donitz's system of war was amazing: he conducted tight tactical control of his U-boat packs in every action right across the Atlantic, an exercise in long-distance command not, I should say, surpassed until the Falklands campaign of 1982. For this purpose the U-boat Command created a signals network which, says our Official Intelligence History; 'for complexity, flexibility and efficiency, was probably unequalled in the history of communications.' The weakness was that such a system involved an enormous output of radio signals, and when the cipher was broken by Bletchley Park this meant a rich flow of Intelligence better than the best espionage. In 1941 it enabled the Submarine Tracking Room and its colleagues in the Trade Plot to anticipate U-boat ambushes and re-route convoys to such effect that probably some 300 ships were saved, and this, says Jurgen Rohwer, was 'more decisive to the outcome of the battle than the U-boats sunk in the battles of 1943.' But when the Germans changed their cipher and added a fourth wheel to the Enigma cipher machine in 1942, the long drawn-out Sigint blackout that ensued by no means put the Submarine Tracking Room out of business. In other words, ULTRA was a highly valued part of Naval Intelligence—but only a part.

I am not going to spoil this thriller by harping on how the battle ended in 1943; you will have to buy the book to find that out. But I want to end by going back now to the question of the value of sinking submarines raised by Professor Marder. In May 1943, the month when the Battle of the Atlantic is reckoned to have really ended, thanks to the combined onslaught of the whole Allied air/sea armoury—ULTRA, D/F, HF/DF, radar, VLR aircraft and all the assorted weaponry—and to the patience, skill and never-failing spirit of the men using it, no fewer than forty-one U-boats were sunk. For the whole year the total was 237. That is a lot of U-boats. Can it be dismissed as just 'a bonus'?

The answer, I suggest, is that as long as the battle was about Britain's survival only, 'bonus' is about right: a very gratifying, encouraging bonus, but not, in the long run, a necessity. Not to be compared with the very large number of ships in convoy which never ceased to ply the trade routes without ever seeing a U-boat or hearing a torpedo explode.

But long before May 1943 the battle had ceased to be just a fight to survive. When the Americans, at the ARCADIA Conference in January 1942, declared their 'Germany First' policy, the lynch-pin of Anglo-American strategy became an amphibious assault on north-west Europe. There were various codenames for this: a forlorn hope in 1942 itself called SLEDGEHAMMER, ROUNDUP for 1943, finally OVERLORD for 1944 all based on a massive American build-up called BOLERO. As I said in The Right o f the Line, from this time onwards this would be the great offensive project of the Alliance; 'whatever contributed to it would promote the prime intention, whatever impeded it would be harmful.'

Upwards of 200 U-boats, aggressively handled, would certainly be an impediment to BOLERO. No BOLERO, no OVERLORD. Only by sinking very large numbers of them could these U-boats be deterred and forced away from the decisive OVERLORD area. Thus the Atlantic victory, as well as being a highly significant defensive success, must also be rated as the basic ingredient of the greatest western offensive of the war. As Captain Donald Macintyre succinctly puts it: The assault on the Normandy beaches in 1944 could not have been attempted had the enemy not first been decisively beaten in the Atlantic.'

It was just as well that it happened when it did. By the end of 1944 a new device, the Schnorckel, and new, revolutionary types of U-boats which could live without surfacing for very long periods, and so made virtually no radio signals, had come upon the scene. With nothing for D/F, HF/DF, radar or ULTRA to feed on, the anti-submarine forces, as 1945 came in, found themselves faced with a very clear and unpleasant view of Square One. The age of the submersible was over; the age of the submarine had begun.