From its creation, the German U-boat arm had its most important bases at Kiel and Wilhelmshaven, in that flat and lonely part of Germany that has long belonged to the German navy. To get to the Atlantic shipping, U-boats had to negotiate the narrow sea lane between Scotland and Norway. Worse, German coastal regions were shallow and could be mined. So, as soon as France was defeated, Admiral Dönitz moved his submarine fleet to its west coast which faced directly to the Atlantic. It was done with remarkable speed and efficiency. On his own initiative, Captain Godt, chief of staff to Dönitz, dispatched workmen from the Germania construction yards at Kiel, and selected men from the flotilla commands. A train loaded with fuel, torpedoes, supplies and paperwork departed from Wilhelmshaven on the day following the French armistice. Less than three weeks later, the U-30, commanded by Kapitänleutnant Lemp, was in Lorient, loading torpedoes. One account records that:
The advance guard of the flotilla staff had moved into the French Naval Préfecture at Lorient. They had plenty of booty – uniforms, footwear, equipment – some of it bearing the names of British and American firms and the date 1918: there were piles of tropical kits, arms, ammunition, food, and a thousand and one items which the enemy had had no time to destroy … And now the flotilla depot was there, with everything one’s heart could desire – transport, fuel, money; only the sanitary arrangements left something to be desired, but that was soon rectified.7
After a brief spell in Boulevard Suchet, Paris, Dönitz set up his headquarters in Kernéval, near Lorient, on 1 September 1940. His commandeered villa near the sea at Lamorplage had belonged to a sardine merchant. Sheltered by trees, it had a view towards Port Louis and the old fort at the harbour entrance. From here Dönitz could watch his U-boats as they came into the harbour and tied up at the wooden prison ship Isère which had once been used to transport French convicts to Devil’s Island in French Guiana. Now it was the first and last mooring for each U-boat that went on an operational trip. Comrades, female naval telegraphers and other well-wishers would gather on the Isère; sometimes a military band played patriotic songs and marches. U-boats departing had their crews paraded on deck; those arriving would often be flying the home-made pennants that denoted the tonnage of their victims.8
One room in the Dönitz mansion was called ‘the museum’. Here, by means of charts, diagrams and the graphs he liked so much, he could see, or show others, the progress of the submarine war measured by such things as the Allied tonnage sunk per operational U-boat day at sea. Here were the turn-round times and the changing enemy tactics and routes. The next room – his ‘situation room’ – had a big plotting table and walls covered with maps and charts. Pins showed the positions of the U-boats and of convoys and RN units, and even – thanks to the men of B-Dienst – the places where the British believed the U-boats to be! There were air-reconnaissance photos and, from secret agents, reports of the sailing of individual ships or convoys. On the map’s could be seen the way in which long-range Sunderland aircraft were being sighted further and further west. Dönitz described the room in which he spent so many hours:
The maps were supplemented by a number of diagrams showing the differences between our local time and that in the various areas of operations, charts showing tides and currents and ice and fog conditions with special reference to the north-west Atlantic … A large globe more than three feet in diameter gave a realistic picture of the wide Atlantic as it really is and was of great assistance in determining distances which could be worked out only approximately on ordinary charts, which, where great distances are concerned, make no allowance for the curvature of the earth’s surface.9
British shipping losses in the first year of the war – Royal Navy and merchant total 452
On that first day of September 1940 his charts showed that his U-boat losses to date – 28 – exactly equalled the number of new boats commissioned in the same period. That still left him fewer than at the start of the war because of the needs of training, repairs, trials and shakedowns. Of his 27 operational U-boats only seven or eight would be at sea on an average day, too few for Dönitz to operate the sort of ‘wolf-pack’ tactics he wanted, though sometimes several boats could be brought together to converge on a target.
The chart recording his successes would have shown an aircraft-carrier, a battleship, three destroyers, two submarines, five auxiliary cruisers and 440 merchant ships estimated at a total 2,330,000 tons. Dönitz used tonnage sunk per U-boat day at sea as a measure of the U-boat arm’s efficiency. By this measure October 1940 was the peak of his success, with five and a half ships sunk each month per U-boat at sea. (The high figures achieved later in the war were sinkings by larger numbers of boats, and Dönitz remained acutely aware of his failure to get back to his 1940 peak.)
The French bases at Lorient, Brest, St Nazaire and La Rochelle were near deep water and difficult for the British to mine. RAF Bomber Command did not mount an all-out bombing campaign against them until it was too late. For in 1941, at Hitler’s command, concrete shelters were constructed over the pens and made so thick and strong that normal RAF bombs had little effect. Virtually indestructible, these pens are still there today. The French show perverse pride in them and permit only their own citizens to look inside.
The Germans also had the benefit of skilled French technicians. Delighting their German masters, the French shipyard workers laboured even harder than their counterparts in Germany. They reduced the turn-around time that U-boats spent in port by no less than 22 per cent. ‘Until this time two and a half boats had been in port for every submarine at sea and the French helped to reduce this figure to a ratio of 1.8:1.’10
As German armies consolidated their conquest of France and the Low Countries in the summer of 1940, the British kept many destroyers and other craft in base, ready to repel an invasion of their islands. Convoys sailed with few escorts, and for much of the crossing had to manage without protection. Out in the North Atlantic the U-boats were sinking merchant ships at a dismaying rate. U-boat commanders, with their battered hats and white roll-neck sweaters, were coming home from patrol to report the sinking of forty or fifty thousand tons of shipping. These undersea aces got the same sort of film star treatment in Germany that the Spitfire pilots (often with similarly battered hats and similar white roll-neck sweaters) were enjoying in Britain. U-boat crews were cosseted. French resort hotels were converted to rest homes for them, or they could return to Germany on the special U-boat train that went backwards and forwards with supplies, ammunition and spare parts. If they stayed near their bases, their high pay (with double pay for each day in the Atlantic operational zone) ensured their warm welcome in restaurants, nightclubs and brothels despite their reputation for boisterous behaviour.
From the bases in France U-boat men could strike at ships bringing fuel, wheat and war supplies to Britain from the United States and Canada, as well as beef from South America, while the routes of vital ore from South Africa and oil from Nigeria were almost on their doorstep. The African convoys were seeking safety further west and the transatlantic routes were going ever more northwards into icy seas. The U-boats followed them.
Aircraft: the lonely sea and the sky
Until war started, the British had given little thought to the weapons needed if aircraft were to sink submarines. The Blackburn Kangaroo, a twin-engined biplane used against U-boats in the final weeks of the First World War, could carry four 250-lb bombs. The twin-engined Avro Anson, which in 1939 comprised well over half of RAF Coastal Command’s aircraft, could carry only four 100-lb bombs. Although these were specially designed anti-submarine bombs their efficiency had never been properly tested. The first chance to measure Coastal Command’s anti-submarine bombs came on 5 September