5© Canadian Military History, Volume 13, Number 4, Autumn 2004, pp.5-18.

How wide is the Atlantic? This title of ourconference has a very direct operationalmeaning in regard to the sea campaign whichdecided the Western democracies’ war with NaziGermany. Well, how wide? For a slow convoysteaming at around 6-7 knots, the Atlantic wasup to three weeks wide – three weeks of enduringthe worst of weather and the hazards of U-boatambush.

On this constant round traffic of convoysbetween North America and the United Kingdomutterly depended not only Britain’s industrial wareffort, but also her very national life itself. It wasestimated in 1937 that Britain in wartime wouldneed 47 million tons a year of imports. Thisgigantic reliance on overseas supplies was thelegacy of the Victorian adoption of Free Tradeback in the era of unchallenged British worldmastery – mastery naval, financial, andindustrial. In that era, Free Trade had broughtenormous peacetime economic benefits toBritain – above all, abundant cheap food fromthe Americas and the Antipodes. But in the verydifferent era of the two 20th Century total wars– the era of the U-boat – this dependency onseaborne imports rendered Britain’s existencemore precarious than that of her allies or hermain European enemy.

By comparison, that enemy, Nazi Germany,being a Continental power, suffered from nocomparable economic vulnerability.

Let me remind you that Britain’s wartimeimports across the Atlantic included not onlybulk supplies like raw materials, foodstuffs, andall the oil needed to keep the Royal Air Forceflying and the Navy at sea, but also suchabsolutely indispensable high-value goods suchas advanced machine-tools, aircraft, trucks,radio and radar components, and weaponry –kit which British industry either could not makein sufficient quantity, or could not make at all.

Here’s one insight into just how precariousBritain’s position became at the worst momentof the Atlantic struggle. In late 1942, it wasestimated that Britain’s cut-to-the-bone importrequirements for 1943 would be 27 milliontons – as against the 47 million deemed essentialback in 1937. In January 1943, actual importtonnage was less than half of what it had been inJanuary 1941. In the three months, November1942 to January 1943, nearly half of Britain’sconsumption of raw materials – the very stuff ofwar production – had come from stocks. Whenthese were exhausted, what then?

This British reliance on the 2,500-mile-wideAtlantic convoy route had been vastly increasedin the summer of 1940, when all Europe wasfinally lost to German occupation. Before thatloss, some 20 per cent of British imports hadcome from relatively nearby sources like theContinent itself, the Mediterranean region, andNorth Africa. By 1941 that proportion haddropped to four per cent. Meanwhile, theproportion of British imports coming fromacross the North Atlantic had risen from 36 per

The Partnership BetweenCanada and Britain in Winning

the Battle of the Atlantic

Correlli Barnett

This article was originally delivered at theBritish Association for Canadian StudiesConference, 5-8 April 2004.

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cent to 54 per cent. This in turn meant a muchlarger commitment of merchant shipping andnaval escorts, with “round-voyage time” risingfrom an average of 99 days before the fall ofFrance to 122 days afterwards.

What’s more, the fall of France hugely swungthe strategic balance at sea to Germany’sadvantage. Now the bases of both U-boats andsurface raiders could be brought forward fromGermany’s North Sea coast to French Bay ofBiscay ports, so giving speedy direct access tothe Atlantic. U-boats being repaired orreplenished in their French “pens” beneath 20-foot-thick concrete roofs would be invulnerableto the heaviest bombs then possessed by RoyalAir Force Bomber Command. Soon a Luftwaffesquadron of long-distance Focke-Wulf Condorsarrived in France to work with the U-boats. Inthis combination of the long-distance U-boat,surface raiders, and the Luftwaffe, Britain faceda peril far more dangerous than in the GreatWar.

No wonder, then, that the Prime Minister,Winston Churchill, wrote to President FranklinD. Roosevelt at the end of 1940:

The decision for 1941 lies upon the seas. Unlesswe can establish our ability to feed this Island,to import the munitions of all kinds which weneed, unless we can move our armies to thevarious theatres where Hitler and his confederateMussolini must be met, and maintain them

there, and do all this with the assurance of beingable to carry it on till the spirit of the ContinentalDictators is broken, we may fall by the way, andthe time needed by the United States to completeher defence preparations may not beforthcoming.

In March 1941 Churchill issued a directiveproclaiming that what he called “the Battle ofthe Atlantic” had begun, with an enemy-attempt“to strangle our food supplies and our connectionwith the United States.” He could have added:“and our connection with Canada.”

The fortunes of this battle were to sway toand fro for the next two years – measured by agrim accountancy of comparative losses: theratio of merchant ships sunk to U-boatsdestroyed or captured; the relative numbers oftrained British and Allied merchant seamen andGerman submariners blown up, drowned ormaimed set against the numbers of freshvolunteers coming forward to replace them; thetotal tonnage of shipping sunk measured againstthe output of Allied shipyards, and of sunkU-boats measured against Germany’s newproduction; the “productivity” of U-boats, interms of ships sunk per U-boat per sortie.

To the opposing admirals and their staffs,these statistics were the equivalent of profit-and-loss accounts or monthly cash flow figures tothe directors of hard-pressed rival businesses.They were scanned with equal trepidation and

An Allied convoy makes its way across the North Atlantic.

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hope by Grand Admiral Eric Raeder, the headof the German Navy, in Berlin, and by Admiralof the Fleet Sir Dudley Pound, the First Sea Lord,in London; by Rear Admiral Karl Doenitz in hisU-boat Command bunker near Lorient, and bythe Commander-in-Chief Western Approaches inLiverpool (Admiral Sir Martin Dunbar-Nasmithuntil February 1941; Admiral Sir Percy Nobleuntil November 1942; and thereafter Admiral SirMax Horton, himself a submariner).

It is perhaps too easy for an academicconference such as ours to discuss historicaltopics in dry documentary terms removed fromactual human life in the past. In the present caseof the Battle of the Atlantic, we must bear in mindthat the comparative accountancy of merchantships and U-boats sunk signified a trulyappalling experience at sea. We have to imaginewhat it was like for the crews of the heavy-ladencargo ships labouring slowly through the hugeAtlantic seas, always conscious that at anymoment a torpedo could consign them suddenlyto those seas in frail lifeboat or raft. We have tokeep in mind the seamanship and tactical skillof the crews of the naval escorts – crews whowere cold, wet, and exhausted from keepingwatch on open bridges swept by spray or greenwater. Crews with their eyes and nerves strainedby the unremitting vigil for shadowing Focke-Wolf Condors, for the U-boat’s squat conningtower or periscope plume or torpedo track amidthe seaway. The Battle of the Atlantic would be

decided by several factors, strategic andtechnological, but above all, it would be decidedby morale.

From the beginning of the war, the Dominionof Canada had provided the absolutely essentialNorth American terminal of this 2,500-mile-widebridge of convoys. The port of Halifax, NovaScotia, became the assembly point for merchantshipping bound for Britain from all parts of theWestern Hemisphere, while St. John’s,Newfoundland – yes, I know Newfoundland wasthen a Crown Colony – supplied a vital, if at firstprimitive, naval base for the Royal Navy on theWestern seaboard of the North Atlantic.

Let’s be clear: given US neutrality until theend of 1941, there could have been NO Battle ofthe Atlantic, and NO British survival if Canadahad not served from the start as thatindispensable North American buttress ofBritain’s ocean bridge.

But here we come to a paradox. In the 1930s,Canadian Prime Minister Mackenzie King hadsteadfastly refused to sign up to any kind of jointCommonwealth strategic planning proposed byBritain. By 1937, Britain, as the Mother Countrymorally responsible for defending the wholeEmpire, was facing what the Chiefs of Staffreckoned to be the worst possible case – a triplethreat by Germany, Italy and Japan to the Empireright across its global spread. Remember, none

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A rare view of a German Type VIIc U-boat in the mid-Atlantic.

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of the Dominions had strong enough armedforces to defend themselves. In particular,Australia and New Zealand were depending ona British promise to despatch the main battlefleetto Singapore in the event of Japanese aggression.

So naturally enough, Britain wanted tomaximise the Empire’s capabilities for collectivedefence. That meant the kind of joint planningand prior collective assignment of forces undera common strategy as was achieved in NATO inthe 1950s. This was what the British hosts triedto achieve at the 1937 CommonwealthConference. In the words of Lord Derby, theSecretary of State for War,

The defence problem is like a great puzzlecomposed of many different pieces, of which theMother Country and the Dominions each heldsome pieces. We want to piece these together soas to make a complete picture.

But Mackenzie King would have none of it.In the first place, Canada, unlike Australia, facedno potential danger of attack and had no needfor British protection. And secondly, as you wellknow, ever since the 1923 Imperial Conference,King had been determined to establish Canadaas a completely independent power with its ownforeign and defence policies. So at the 1937Conference, King cut Lord Derby off at the knees,telling him that,

I think I ought to make it clear that as to whatextent Canada would participate in a war at anytime must be considered a matter which her ownParliament will wish to decide.

In the event, of course, Canada’s ownparliament DID freely decide to participate inthe war against Nazi Germany, and to themaximum extent of Canada’s resources. Sodespite Mackenzie King’s peace-time huffingsand puffings, Canada would after all fight as aclose ally of Great Britain.

But just the same, Canada in September1939 had little enough to contribute to a struggleagainst the U-boat. The Royal Canadian Navythen consisted of only seven destroyers and fiveminesweepers, and those were divided betweenher Atlantic and Pacific coasts. In January 1939it had been planned to increase the number ofdestroyers to 18, plus 16 minesweepers andeight anti-submarine vessels. The newdestroyers, at 2,000 tons and with eight 4.7-inchguns, were really almost light cruisers, and theywould take three years to build. So in themeantime, Canada virtually developed two naviesside by side – the regular Navy which wouldoperate the big destroyers, and a reserve navywhich manned the humble corvettes on convoyduty – that is to say, the Royal Canadian NavalReserve and the Royal Canadian Naval VolunteerReserve. And it was these reservists manning thecorvettes which saw most action in the earlyyears.

The Canadian naval authorities faced aspecial problem of expansion: unlike the RoyalNavy, they had no existing large trainingestablishments and training staffs. This meantthat crews of corvettes were routinely pillaged

HMCS Dundas, a Flower-Class corvette photographed shortly after it was commissioned in April 1942. In 1940 the RCN

ordered a second six ship program of short forcastle corvettes which were outwardly similar to the original program. The

most important change, water-tube boilers, is not evident, but her lack of minesweeping gear is, and her bridge wings

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of their best officers and seamen to man the newtraining centres or to act as the experiencedcadres of new crews in new corvettes. What’smore, the first Canadian-built “Flower-class”corvettes in spring 1941 lacked the latest kit anddesign modifications of their British counter-parts. Here were all the classic problems andcosts of belated and improvised militaryexpansion.

Only in June 1941 did the RCN really jointhe Battle of the Atlantic, when the NewfoundlandEscort Force came into service. Commanded bya British-born career sailor in the RCN,Commodore Leonard Murray, it consisted of 13destroyers (seven Royal Navy, six RCN) and 21corvettes (17 of them RCN). Its task was toprotect convoys between points east ofNewfoundland and south of Iceland.

I now want to summarise the evolution ofCanada from a very junior role in the Atlanticcommand-and-control system to a full and equalpartnership with Britain. But this is whereCanada’s colossal neighbour comes into thestory. I can only telegraph the step-by-stepinvolvement of the United States in the Atlanticbattle in the course of 1941 even while sheremained technically neutral. In January the USNavy set up a new “Support Force, Atlantic Fleet,”

composed of destroyers and an air component.American naval and air bases for the newSupport Force were rapidly built at Argentia,Newfoundland (leased from Britain), inGreenland, near Reykjavik in Iceland, and inNorthern Ireland and Scotland. On 11 April1941, the American government extended the so-called “Security Zone” off the coasts of Northand South America eastwards to 26 degreeswest, or to within some 750 sea miles of Portugal.Within this zone the US Navy would report theposition of enemy U-boats and warships to theBritish Admiralty, leaving it to the Royal andRoyal Canadian Navies to do the rest.

Then at the Argentia summit betweenRoosevelt and Churchill in August 1941, it wasagreed that the United States would assumeoverall responsibility for convoy protection westof the “Mid-Ocean Meeting Point” – MOMP forshort – south of Iceland. So the Canadian-commanded Newfoundland Escort Force nowpassed from the control of the British C-in-CWestern Approaches to Rear-Admiral A.L.Bristol, US Navy, commanding the SupportForce, Atlantic Fleet.

The point to note here is, that this majordecision in regard to the deployment andcommand of the Royal Canadian Navy was taken

The principle actors – Left: Admiral Sir Max Horton, RN, Commander-in-Chief Western Approaches Command from

November 1942; Centre: Rear Admiral Leonard Murray, RCN, Commander-in-Chief Canadian Northwest Atlantic

Command from April 1943; Right: Grand Admiral Karl Doenitz, Commander of the German U-boat fleet.

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without any consultation with the Canadiangovernment or naval authorities. Well, Churchillfor his part certainly saw all the Dominions assubordinate to British strategic decisions – heshowed this in his relations with Australia andNew Zealand over the use of their army divisionsin the Middle East and Far East. Albeit from adifferent perspective, Roosevelt and hiscolleagues likewise took it that London was theone centre of decision they had to deal with inregard to the armed forces of that strange hybrid,the British Commonwealth.

Canada, therefore, was very much the juniorpartner. But here is another paradox. Thoughtechnically still neutral, the United States hadbecome by the autumn of 1941 a fightingparticipant in the Battle of the Atlantic equal inweight to Great Britain. But in the months afterbeing bombed and torpedoed into fullbelligerence by the Japanese attack on PearlHarbour on 7 December, the US role in theAtlantic actually shrank. The reason was simple:the war in the Pacific left the US Navy desperately

short of ships. And so by mid-summer 1942,the Royal Canadian Navy had replaced the USNavy as the Royal Navy’s principal partner inthe Atlantic – carrying 46 per cent of the burdento the British 50 per cent, and the American fourper cent.

Even so, an American admiral continued tobe responsible for convoys west of the CHOP line(Change of Operational Control) at 26 degreeswest. This anomaly was not to be resolved untilan Atlantic Convoy Conference in Washington inMarch 1943. For Canada, this conference proveda turning-point in more than one sense. First, itwas the first genuinely tripartite conference heldon the Battle of the Atlantic. Second, it wasconvened at Canada’s own request. And third, itresulted in the Royal Canadian Navy taking overfrom the US Navy the responsibility for theAtlantic west of a new CHOP line at 47 degreeswest. To discharge this responsibility, a CanadianNorth-West Atlantic Command was to be set upunder Leonard Murray, now a Rear-Admiral, asC-in-C, and based in Halifax.

It certainly helped the Canadians atthis conference that Ernie King, the USChief of Naval Operations, with his eyeson the Pacific war against Japan, wasonly too glad to be rid of the burden ofthe North Atlantic. What matters is, thatCanada had now achieved an equalpartnership with Great Britain in the keycampaign of the war against NaziGermany.

And this partnership had comeabout just when that campaign seemedto be on the point of being won by theU-boat. So now I’m going to turn to theprotracted struggle itself.

We are, of course, talking about thesecond Battle of the Atlantic against theU-boat, the first being narrowly won bythe Royal Navy in 1917. Both sides drewtheir own lessons – or illusions – fromthat experience; lessons or illusionswhich in the interwar period they thenapplied to planning for a new conflict.

Seamen loading depth charges onto throwers

aboard the Canadian corvette, HMCS

Mayflower, in 1941.

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In the Royal Navy’s 1917 victory over theU-boat, new technology had certainly played itspart. Hydrophone listening gear helped to locatea U-boat lurking beneath the surface. The depth-charge lobbed over the stern of a escort couldcrack its pressure hull if close enough. Flying-boats and airships of the Royal Naval Air Servicehad patrolled home waters on the lookout forsurfaced submarines.

Yet far more important still as an ingredientin the victory was the convoy system itself. Itssuccess really lay in an equation of space andtime. As more and more shipping becamegrouped into convoys, the U-boat found the seasemptied of prey. It could cruise for days withoutsighting a ship. If and when it did encounter aconvoy (and even a large convoy was a minorobject in the vast wastes of the sea), it only hadtime for a single attack before the convoysteamed steadily out of range. Moreover, theconvoy was an offensive rather than merelydefensive system, because it drew the U-boatwithin range of the escorting destroyers.

Yet in the 20 years of delusory peace betweenthe world wars, the British Admiralty forgot thishard-learnt lesson. Can you believe it, but notuntil 1937 was it accepted that to bring inBritain’s estimated annual wartime requirementsof 47 million tons of imports would once againdemand a full convoy system. What’s more, inthe rush of belated rearmament there was littlespare capacity in British shipyards to build thehuge numbers of escorts needed. Royal Air ForceCoastal Command too lacked aircraft ofsufficient range for ocean patrolling; lacked aswell bombs capable of even damaging, let alonesinking, a U-boat. In any case, the need for closecooperation between surface escorts andmaritime airpower had also been forgotten.

Why did the Admiralty in the 1930s soneglect the operational lessons of the Great War?The answer was simple. The Royal Navy reposedan exaggerated faith, shared by the RoyalCanadian Navy, in an improved device fordetecting submerged U-boats. This was theASDIC (from Allied Submarine Detection

The Robert Tuttle, on fire and sinking after being torpedoed by U-701 on 12 June 1942. Tankers

were high priority targets due partly to the oil they carried, but also because of their size.

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Investigation Committee) echo-sounder – todaycalled “sonar.” But unfortunately the GermanU-boat arm had by 1939 adopted a new tactic(first tried out towards the end of the Great War)of attacking convoys at night on the surface. Thisnullified Asdic. Moreover, the U-boat under dieselpower on the surface was much faster than cargoships, and so could hang on to a convoy in orderto launch sustained strikes.

Mercifully, the German naval staff in the1930s, for its part, had neglected expansion ofthe U-boat arm in favour of commerce raiders –12,000-ton “pocket” battleships like the AdmiralGraf Spee, the 32,000-ton fast battleshipsScharnhorst and Gneisenau, and the two51,000-ton super battleships, Bismarck andTirpitz, still building in 1939. So on the outbreakof the Second World War, Germany had availableonly 21 operational U-boats suitable for Atlanticsorties, as against the estimated 200 needed tocut Britain’s oceanic lifeline for good.

Both sides therefore began the second Battleof the Atlantic in comparable states ofunreadiness. Indeed it was the threat of Germansurface raiders (including heavily-armeddisguised merchant ships) that gave theAdmiralty the greater anxiety during the earlymonths of the war. They ranged the North andSouth Atlantic and the Indian Ocean, sinkingmerchantmen at far distant points. The tonnagesunk was not vast, but the hunt for the elusiveraiders stretched the Royal Navy’s resources tothe limit.

Two things ushered in the full ferociousstruggle with the U-boat. The first I’ve alreadymentioned – the establishment in 1940 ofU-boat bases on France’s Atlantic coast. Thesecond was the ultimate failure and destructionof Germany’s surface ships in which GrandAdmiral Raeder had misplaced such faith. Thisfailure was consummated by the sinking of theBismarck in May 1941. So the hour of the U-boathad come.

The Royal and Royal Canadian Navies nowfaced perhaps the most formidable enemyadmiral in the history of British seapower – KarlDoenitz, a man sharp of mind and ruthless ofwill. Doenitz had now perfected his new systemof U-boat warfare. By means of an elaborate radiocommunications net and the Enigma encipheringmachine, he centrally directed his offensive from

his command bunker near Lorient. Once aconvoy had been located by a Focke-Wolf Condor,a U-boat, or, for long periods, by reading theAdmiralty’s top-secret convoy ciphers, Doenitzwould concentrate “wolf-packs” of up to 40U-boats in a sustained attack. Very different fromthe lone cruising U-boat of the Great War.

There was another big difference. In thatearlier conflict, the U-boat offensive had beenlimited to the Western Approaches round theBritish Isles – which was one reason why Canadawas then little involved, But this time round,Doenitz’s new and bigger U-boats could carrytheir offensive far into the Atlantic. This meantthat instead of merchant ships coming togetherinto convoys for the final run to British ports,as in the Great War, they would now have to sailin convoy right across the Atlantic. Hence thenew and vital importance of Canada as thewestern buttress of the system. But in turn, theneed to protect convoys over oceanic distancesmeant a far greater need than in the Great Warfor escort vessels and patrolling aircraft.

The outcome of the conflict depended on theability of these vessels and aircraft to find theexact position of U-boats, and then sink them.Pretty obvious, I know, but it took the naviesand air forces of Canada and Britain three anda half years of war fully to develop that ability.

The basic requirement for both the findingand the sinking lay in a large enough number ofappropriately equipped escorts and aircraft. Thekey here is “a large enough number.” Take thebasic work-horse and weapons-platform of theAtlantic battle, the corvette. In 1939-41, therewas a desperate shortage of these – partlybecause Britain’s pre-war rearmamentprogramme had given priority to building shipsfor the battlefleet; partly because, to begin with,the wartime output of British and Canadianyards was so limited. Only by the end of May1941 had enough corvettes been built to enablethe first convoy to be escorted the entire wayacross the Atlantic from Halifax to Britain insteadof leaving an unprotected gap in mid-ocean. Atthis time, 99 new corvettes were building – and55 of them in Canada.

I should mention here that, by the climax ofthe Atlantic battle in 1942-3, Canada had createdan essentially corvette navy, with no fewer than120 of the vessels on the strength of the RCN.

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As a weapons platform and a livingspace, the Flower-class corvette had thedisadvantage that it rolled like a barrel.And to begin with, Canadian-builtcorvettes had only a magnetic compassand no gyro-compass. The Flowers werepowered by an obsolete design of a four-cylinder triple-expansion engine, sinceBritish industry lacked the capacity forlarge-scale production of diesels.Because of this, the corvette, at amaximum speed of 14-15 knots, wasactually slower than a U-boat’s 18 1/2knots on the surface.

What’s more, better replacementswere slow to come out of the shipyards.In 1942, delivery of the new River-classfrigates was still being awaited. Only inSeptember of that year did the RoyalNavy have enough frigates anddestroyers to create its first huntinggroup to serve as a supplement to theclose convoy escort, with the specifictask of chasing U-boats to the death.

Comparable delays occurred in thedevelopment of on-board devices for pin-pointing a surfaced U-boat’s position.Only after mid-summer 1942 were escort shipsprogressively fitted with radar and HF/DF [HighFrequency Direction Finding]. Already installedfor some time in shore stations, HF/DF locateda U-boat from its radio transmissions, and ofcourse, Doenitz’s system of central directiondemanded copious use of radio. Even then,Canadian ships lagged behind Royal Navy escortsin getting radar and HF/DF – a penalty ofdependence upon the manufacturing capacity ofother countries. In any case, it was not until early1943 that ship-borne HF/DF and radar becomestandard kit in all Atlantic escorts, British orCanadian.

And what about the means of killing U-boatsonce they’d been located – apart, that is, fromthe traditional gun and the depth charge droppedover the escort’s stern? Because of bureaucraticrivalries and obstruction within the British navalresearch establishments, it was not until late1942 that escorts began to be equipped with the

“Hedgehog,” a forward-firing battery of 24 mortartubes lobbing a broad spread of 65-pound high-explosive bombs over a submerged U-boat.

In the air, there were similar problems ofdeveloping the means both to locate a U-boatand then destroy it. Only in mid-1942 were thetwo air forces equipped with a shallow-settingdepth charge filled with a powerful new explosive,Torpex, and lethal to U-boats diving or justsubmerged. As for finding U-boats in the firstplace, the British aircraft industry had failed toproduce effective long-range maritime aircraft insufficient quantity, and so RAF CoastalCommand and the Royal Canadian Air Forcebecame largely dependent on the AmericanConsolidated PBY-5 Catalina flying boat, and theMark II B-24 Liberator bomber. Just the same,such aircraft operating from bases in Canada,Iceland, and the British Isles lacked the rangeto give continuous air cover across the wholeNorth Atlantic. And it was in the resulting 700-

Bridge personnel of HMCS Ottawa watch as a

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mile wide “mid-Atlantic air gap” that in 1942Doenitz concentrated his ever more lethaloffensive.

The British and Canadian naval staffsrecognised that only Very Long Range (VLR)aircraft were capable of maintaining continuouspatrols over this gap. So for many months in1942 they pleaded to be allotted just 40 suchaircraft. But in any case, RAF Coastal Commandalso lacked enough medium-range bombers forthe task of attacking U-boats in the Bay of Biscayon their way to and from the Atlantic. So CoastalCommand and the Admiralty also urgentlyrequested that bombers be transferred from thestrategic air bomber offensive on German citiesto the Battle of the Atlantic.

Yet Winston Churchill failed to give speedyand decisive backing to either of these requests.Here was perhaps the most potentiallydisastrous episode of his whole conduct of theBattle of the Atlantic. Why do I say this? Becausefor want of a handful of very-long-range 10-cm-radar-equipped aircraft, Britain and Canada very

nearly lost the Battle of the Atlantic in late 1942and early 1943.

To be beaten by the U-boat would mean notonly British industry at a standstill, the nationstarving, and, for that matter, Bomber Commandgrounded for want of fuel, but also no possibilityof a later liberation of Western Europe by British,Canadian and American armies. As Sir DudleyPound wrote at the time: “If we lose the war atsea, we lose the war…”

So here was the absolute crux of the conflictwith Nazi Germany. There is a fascinatingparallel between U-boat Command’s attempt todefeat Britain by wrecking her economy; andBomber Command’s attempt to defeat Germanylikewise. The question in 1942 was: who waswinning the race? And the answer clearly was,based on the evidence, the U-boat. Over the fullyear 1942, Doenitz’s U-boats sank more thansix million tons of shipping, as against therelatively slight damage so far done by thebombers to German industry. Yet at the beginningof 1943, RAF Coastal Command and the RCAF

A Consolidated Liberator of No.10 (BR) Squadron, RCAF, Goose Bay, Labrador, Newfoundland, May 1943.

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still had only received a handful of the VLRaircraft they needed.

This was not the only punch-up between theAdmiralty and the Air Staff in 1942. The key topinpointing a U-boat’s conning tower or evenperiscope amid the clutter of a seaway lay in thenew 10 centimetre ASV (Air-to-Surface-Vessel)Mark III radar. Moreover, this could not bedetected by a U-boat’s Metox anti-radar device.Yet two years after testing the prototype, not asingle ASV Mark III had yet seen service withthe RAF or the RCAF. Why the colossal delay?Answer, production muddles in the British radioindustry – and that was despite rescue byAmerican supplies of the magnetron thermionicvalve and precision components.

But there was another reason too.Technically the ASV III was virtually the same asBomber Command’s target-finding device H2S.So fierce competition raged between the Navyand the Air Force for the available hand-builtproduction. Only in November 1942, with agrowing likelihood that Britain might lose theAtlantic battle and hence the war, did the Britishgovernment take the decision to convert 40 H2Ssets into ASV Mark IIIs. Just the same, the firstCoastal Command squadron was not to beequipped with them until February-March of1943 – perilously late.

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Right: Ground crew load a depth charge aboard a

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And I mean “perilously late” in terms of aU-boat offensive now rising to its climax, withsome 220 boats on the hunt in the Atlantic. Anda key factor in this peril was one that I have notso far mentioned – the top secret strugglebetween Britain’s Government Code and CipherSchool at Bletchey Park (that is, the “Ultrasecret”) and the German B-Dienst to read eachother’s signals but at the same time keep theirown inviolate. The swinging fortunes of thefrontline battle at sea over the previous two yearsclosely reflected the current balance of this secretstruggle.

From spring 1941 until February 1942,Bletchley Park was able to read the voluminousradio traffic between U-boat Command and itsU-boats transmitted via the “Enigma” electro-mechanical enciphering machine. This enabledthe Admiralty to re-route convoys clear of U-boatambushes, as well as locate U-boats (and their“milch cows” or tanker U-boats) for destructionby aircraft or surface forces. Although Doenitzwas deeply troubled by the apparent ability ofhis enemy to anticipate his plans, he neversuspected that Enigma itself had been cracked.

But in February 1942 the enemy added afourth rotor to his Enigma machine, multiplyingmany times the complexity of the enciphering.This was the so-called “Shark” cipher. With

Bletchley Park henceforward unable to readDoenitz’s signals, the Admiralty could no longerroute the convoys clear of U-boat ambushesexcept by informed professional guesswork. Thiscrippling setback occurred just when U-boatnumbers in the Atlantic were rising fast. Itcontributed to the ever more appalling loss ofmerchant shipping in 1942, that year when theAllied navies and air forces still lacked variouskinds of vital equipment.

Only in December did Bletchley Park succeedin cracking Shark, and even then the task ofdecrypting could be slow or only partiallysuccessful.

Meanwhile, B-Dienst, for its part, could readthe British convoy cipher throughout 1942, soenabling U-boat Command to accurately locateits mass ambushes. B-Dienst was onlytemporarily baffled when in December theAdmiralty altered the convoy cipher. By February1943, the Germans had again cracked it – justin time for the colossal convoy battles of Marchand April.

I should say at this point that, althoughCanada did not participate directly in theattempts to break the Shark cipher, her radio-intercept and direction finding (DF) stations hadformed an indispensable component of the North

A convoy assembling in Bedford Basin, Halifax, 1941.

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Atlantic signals intelligence (SIGINT) networkever since the beginning of the war. From May1943 onwards the Submarine Tracking Roomin Ottawa received the full output of Enigmadecrypts, while a free exchange of ideas andinformation was carried on via a direct signallink between Ottawa and the Tracking Room inthe Admiralty’s Operational Intelligence Centre.So in this secret struggle of SIGINT as well, aclose partnership was forged between Canadaand Britain.

Now I’d like to return to the battle at sea,when towards the end of 1942 it began to lookas if the convoy system itself might break down.In December, convoy ONS154, escorted by aCanadian group of one destroyer, the St.Laurent, and five corvettes, lost 14 out of 45ships in a four-day battle with a pack of 20U-boats. It sank only one U-boat in return.

In and after February 1943, when B-Dienstcould again read the British convoy cipher, eventhe most heavily escorted convoys lost manyships. That same month of February, convoyON166 lost 14 ships out of 63 in return for onlytwo U-boats destroyed out of 21 in the wolf-pack.Yet this convoy was escorted by four Canadian

corvettes and one British, plus a Polish destroyerand two American Coast Guard cutters. InMarch, things got even worse. Seventeen U-boatshung on to convoy SC121 as it struggled throughhorrific storms and sank 13 ships without lossto themselves. In the catastrophic first threeweeks of March, no fewer than 97 merchantships had gone down, three-quarters of them inconvoy, the cornerstone of anti-U-boat warfarein both world wars.

It was now no longer a question of the U-boateventually wearing down Allied shippingresources by sheer attrition; it was a question ofthe Atlantic soon becoming impassable – withcatastrophic consequences for the whole courseof the war.

Yet only two months later Doenitz (now C-in-C of the German Navy) had withdrawn hisboats from the Atlantic in acknowledgement ofdefeat. This astonishing turn of fortune was theresult of several factors coming together in thenick of time. As I’ve mentioned, Bletchley Parkhad at last begun to crack the four-rotor Enigmamachine, enabling it again to read U-BoatCommand’s voluminous radio traffic. By now,all British and Canadian escort ships were

The harbour at St. John’s, Newfoundland, 26 September 1942. The natural harbour, with its abrupt outlet to the ocean,

provided a vital, if at first primitive, naval base for the Royal and Royal Canadian Navies on the Western seaboard of the

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equipped with HF/DF, and could also home inon this radio traffic. Thus the very sophisticationof the Doenitz system proved a major source ofvulnerability.

And the problem of the mid-Atlantic air gaphad at last being solved. At the end of Marchappeared the first of American-built escortcarriers, the USS Bogue, to provide convoys withtheir own air cover. By April the Royal Navy hadformed three such escort carrier groups. And inthis same month, the strength of the RoyalCanadian Air Force and RAF Coastal Commandin Very Long Range aircraft fitted with 10 cmradar had risen to 41 from a winter low-point of6. Add in convoy escorts now equipped with theHedgehog mortar, and aircraft carrying Torpexdepth charges, and everything had come togetherat last.

Yet it would not be the shipbuilders andarmourers and boffins of the opposing sides anymore than the code-breakers who wouldultimately decide which way the battle would tipthat critical April and May of 1943, but thesailors ranged against each other in the Atlanticfront-line itself. Despite all the cumulative lossesof past years, despite all the dangers of U-boatinfested waters, the seamen of the British andAllied merchant marines continued unflinchinglyto sail their slow and vulnerable vessels acrossthe Atlantic. As for the ships’ companies of theRoyal Navy, Royal Canadian Navy, and Alliednavies, it is enough to say that they cheerfullyand ever-more skilfully went on doing their duty.In the event, it was the German attackers,especially the novice captains and batch-trainedcrews manning the new U-boats coming off theproduction lines, who were the first to flinch.From the end of March 1943 onwards U-boatswere signalling U-Boat Command to offeringenious excuses for failing to press theirattacks home or for aborting sorties; and U-BoatCommand was sternly signalling back to stiffenmorale and resolve. But in April the U-boats sankonly half the tonnage of March.

Doenitz’s cutlass was beginning to bend inhis hand. In May, however, he made his supremeeffort, concentrating as many as 36 U-boatsagainst single convoys – and encountered Britishand Canadian sea and air power over the Atlanticin all its mature panoply. In a series of gigantic

running battles, Doenitz lost 41 U-boats in returnfor only a handful of sunk merchant ships. On22 May, U-Boat Command made an almostdespairing signal of supposed encouragement toits captains:

If there is anyone who thinks that combatingconvoys is no longer possible, he is a weaklingand no true U-boat captain. The battle of theAtlantic is getting harder but it is the determiningelement in the waging of the war.

This signal, once decrypted, made astonishingreading for Western Approaches Command andCanadian Northwest Atlantic Command. For thefirst time in history the victor literally read themind of the vanquished at the moment whenhope dies and the will begins to break. Soon evenDoenitz had to accept that for the time being atleast he was beaten. So the signal went out tohis captains to withdraw from the fray. The NorthAtlantic suddenly emptied of U-boats. Theconvoys began to steam across virtuallyunscathed. It was if a steel gauntlet had relaxedits grip on the Allied throat.

Despite Doenitz’s hopes of later mounting afresh and this time successful offensive withrevolutionary new types of U-boat, the victoryproved final and decisive. Thanks therefore tothe Allied navies and air forces, Britain wouldsurvive; American and Canadian forces wouldcontinue to pour into the British Isles inpreparation for the invasion of Europe; thatinvasion would successfully take place in June1944; and in the spring of 1945, nourished byseapower, the Allied armies would advance intothe heart of Germany.

In my judgement, none of all this would havebeen possible without that partnership betweenBritain and Canada which was sealed at themoment when Canada declared war on NaziGermany on the 10th of September 1939.

Correlli Barnett is a much-publishedhistorian. His first book was The DesertGenerals (1960) and he has published manybooks since, including Engage the EnemyMore Closely: The Royal Navy in the SecondWorld War (1991). Barnett is a Fellow ofChurchill College, Cambridge, and a formerKeeper of the Churchill Archives Centre.