The 'Happy Time'
on the enemy sea communications is
the proper purpose of sea warfare."1
Karl Dönitz. 1939.
In charge of the Kriegsmarine’s U-boat arm was Admiral Karl Dönitz (pictured right) who, in September 1939, had 57 U-boats at his disposal, of which 27 were ocean-going. Until the fall of France the range of the U-boats had been constrained geographically; access to the Atlantic convoy routes necessitating long and risky journeys from the northern German ports around the north of Scotland. With the acquisition in June 1940, however, of the French Atlantic ports of Brest, Lorient, Saint-Nazaire, La Pallice and La Rochelle Dönitz could take advantage of increased dockyard capacity and proximity to the convoy lanes, which enabled him to extend operations into the central and western Atlantic. Previously arbitrary and sporadic U-boat actions were transformed into more regular and consistent attacks on convoys.
To counter the protection provided by travelling in convoy Dönitz had, in the inter-war period, developed 'wolfpack' tactics, whereby packs of submarines co-ordinated and guided by radio would be deployed on the surface at night. Operating on the surface enabled the U-boats to match and exceed the speeds of the merchant ships and overwhelm their escorts. Dönitz deliberately concentrated his attacks on the merchant ships. He could see the strategic benefits of starving Britain of essential food and supplies. He was also astute enough to realise that the U-boat would not have been able to win a fight against the Royal Navy.2
The Asdic submarine detecting device was useless against vessels on the surface and the low silhouettes of the U-boats were virtually invisible under the cover of darkness. These tactics were based on those used successfully in the latter months of 1918, and it was publicly stated by the Germans before the Second World War that it would be their intention to operate the U-boats in surfaced night attacks.3 Indeed Dönitz himself had in 1939 published a monograph 'Die U-bootswaffe' (The U-boat arm) which advocated a trade war by U-boats and extolled the tactical virtues of surprise surface attacks at night. British intelligence apparently missed its publication and by the time the Admiralty came by a copy, in 1942, it was too late.4
Dönitz had refined the tactics following problems implementing pack-type attacks in the first few months of the war. Pack attacks against convoys sailing to the UK were best carried out, he concluded, as far out in the Atlantic as possible to give the U-boats several days to press home repeated attacks. Secondly, U-boats making contact with convoys should not attack immediately but shadow the convoy and call up other boats. When the pack had assembled they should attack simultaneously in one massive blow, overwhelming escorts and scattering the convoy.5
However, it was not just the acquisition of the new bases on the French Atlantic coast and Dönitz's tactics which explained the success of the U-boats between May and December, 1940, a period which became known to the U-boat arm as 'Die Glückliche Zeit' (the 'Happy Time'). According to Blair :
"Numerous factors had contributed to the slaughter : intelligent and intuitive deployment of the few U-boats available, leading to the pack attacks on seven different convoys; boldness, skill and confidence on the part of the two dozen skippers; excellent torpedo performance in night surface attacks; inadequate and inept convoy-escort and ASW measures; and, lastly, not a little luck"6
In the autumn of 1940 the U-boat arm had begun to overcome problems with faulty torpedoes which had seriously undermined earlier operations against merchant and naval shipping.7 Dönitz had been so exasperated by the problem that in May 1940 he wrote in his war diary: "I do not believe that ever in the history of war have men been sent against the enemy with such useless weapons."8 The problem was partly solved by copying the impact pistols from captured British torpedoes.
Furthermore, the British authorities were compelled to re-route all ingoing and outgoing shipping through the North Channel between Ireland and Scotland in order to avoid attacks from the air. As a consequence shipping bottlenecks developed in this area offering tempting concentrations of vessels for the U-boats.9 On August 17th 1940, in response to convoy rerouting Hitler sanctioned unrestricted submarine warfare out to 20 degrees west longitude, giving the U-boats more space and time to attack convoys. The attack area was extended well beyond British home waters.
At the start of the war there had been an acute shortage of escort vessels, a shortage compounded in the Atlantic theatre by the withdrawal of ships to assist in the Dunkirk evacuations, during which many were lost and damaged. Many others had been lost or damaged in the Norway campaign, had been sent to the Mediterranean or retained as protection against the threatened invasion of Britain. This large-scale withdrawal of the convoy surface and air escorts had, as a consequence, "denuded merchant shipping of any effective scale of defence and given the U-boats almost a free hand."10 The attack on HX72 also came as Churchill was negotiating with President Roosevelt for 50 American destroyers as part of the lend-lease arrangements - the first would not become operational until October 1940, with most others not available until 1941 - and before the resources of the rapidly expanding Royal Canadian Navy could be drawn on.11
To compound the problem many of those escort ships which were available were often deployed on fruitless hunter-killer missions against U-boats, leaving few available for convoy protection purposes. There was disagreement within the Admiralty on this. The deployment of ships in hunting groups at the expense of convoy protection duties was a policy supported by the First Sea Lord and by Churchill. It was an approach which did not produce the desired results but was persisted with for some years, proving disastrous for convoys in the early part of the war.12
When wolfpack offensives began the British found themselves unable to respond effectively. According to Churchill "when the full fury of the storm broke, we lacked the scientific equipment equal to our needs."13 The parlous state of the Royal Navy's convoy escort skills and capabilities at the outbreak of the war are well described in the following passage :
"when war broke out...no properly designed and equipped aircraft were available for convoy escort. No effective depth-charge had been developed. No major oceanic exercise was held between the wars....Convoy-passage exercises, when they were held, were designed more to give destroyers practice in operating their Asdic, which was generally thought to have made the submarine impotent.......No policy for tactical convoy formation Ws laid down, no evasive measures devised, no moves to distract or sink attacking submarines rehearsed.14
Radar was not to prove a valuable weapon in the fight against surfaced U-boats until 1941, although technical production problems had been overcome by March 1940 and by the end of 1940 both aircraft and ships were being equipped with radar units.15 This came, of course, too late to benefit the ships and crews of convoy HX72. Their main assailant, Joachim Schepke, was destined, however, to become the first victim of this new technology.
There was also the weather, which was extremely favourable to the U-boats, and crucially an element of chance - the small number of U-boats available at the time meant that it was "largely a matter of luck if a U-boat sighted a convoy early enough for it to summon the other U-boats by sending out shadowing reports and homing signals."16 This was acknowledged by Dönitz who noted that "in all cases first contact (with the convoys) was a matter of chance. The convoy approached a U-boat."17
Dönitz believed that with a force of 300 U-boats he would have been able to isolate and strangle Britain. By September 1940 he still had just 61 boats. The target level of 300 was not achieved until July 1942, but by this time Britain had been able to requisition and charter 7 million tons of foreign ships, could call on American shipyard capacity, and long-range aircraft were progressively reducing the 'air-gap' in the Atlantic within which U-boats could operate safely on the surface.18 Of course had the Germans actually built 300 U-boats in the late 1930's this would have created a completely different geopolitical climate and almost certainly would have provoked other nations into putting into place countermeasures, including the construction of more destroyers and anti-submarine aircraft.19 Nevertheless considering the havoc caused by the few boats available during the 'Happy Time' it is not difficult to imagine that a substantially larger U-boat force at the outbreak of the conflict might have dramatically changed the balance of advantage in the war.
See Battle of the Atlantic Bookstore for fuller