The Storm of War - Andrew Roberts [204]
The battle of the Atlantic provided some nerve-wracking moments for British strategists: in March 1941 alone, U-boats sank forty-one ships. Yet that same month three of Dönitz’s best U-boat captains were neutralized. Germany’s top ace Otto Kretschmer – who had sunk forty-six ships totalling 273,000 tons – was captured after his U-99 was depth-charged and forced to the surface. Günther Prien, who had torpedoed the British battleship Royal Oak in Scapa Flow in October 1939, was killed when his U-47 was sunk by the destroyer HMS Wolverine. Finally Joachim Schepke was killed in an attack by an escort group commander, Captain Donald MacIntyre. An even greater blow fell that month when – in an escalation of ‘neutral’ America’s aggression – the United States announced that the waters between Canada and Iceland would thenceforth be protected by her Navy, thus allowing the Royal Navy to concentrate on protecting convoys. In September 1941, Roosevelt gave American ships permission to fire on German submarines wherever they saw them. ‘So far as the Atlantic is concerned,’ the American Chief of Naval Operations Admiral Harold Stark noted privately of the shooting war, ‘we are all but, if not actually, in it.’
After Enigma had been cracked in April 1941, between July and December 1941 Allied convoys were re-routed so expertly that not one was intercepted in the North Atlantic.32 Although there were still significant losses – over 720,000 tons were sunk in that period – experts calculate that more than 1.6 million tons were saved. Of course, if the Germans had started the war with enough U-boats, thereby closing the gaps in the ocean between them, no amount of re-routing could have saved the convoys. In May 1941 Churchill warned Roosevelt that if 4.5 million tons of shipping were lost during the next year, with the USA building 3.5 million and Britain 1 million, they would be ‘just marking time and swimming level with the bank against the stream’.33 Yet that month was the first that a west–east convoy was given escorts that sailed the whole way across the Atlantic with them. By September 1941, however, Hitler’s belated submarine-building programme had started to bear fruit, and Dönitz now had no fewer than 150 U-boats in commission, with which he would try to wrest victory in the battle of the Atlantic.
When the war broke out, both the British and German Admiralties assumed that the great German surface ships would be crucial in deciding whether Britain survived or starved. It was thought by London and Berlin that if these capital ships could dominate the Ocean Gap, the New World would be incapable, to adopt Churchill’s phrase in his ‘fight on the beaches’ speech, of stepping ‘forth to the rescue and liberation of the Old’. If, on the other hand, the Royal Navy and its Canadian and later American counterparts could sink these huge vessels, the danger was thought to be far less great. On the outbreak of war Graf Spee and Deutschland were already stationed to attack the trade routes, and Scharnhorst and Gneisenau put to sea in November 1939.
As recounted in Chapter 1, the forced scuttling of Graf Spee outside Montevideo harbour on 17 December 1939, the victim