The Storm of War - Andrew Roberts [210]
Part of the explanation for the heavy losses on the Atlantic and Arctic convoys was that the British convoy code had been cracked by German intelligence, something that was not discovered until after the war. In February 1942 the German Beobachtungdienst (radio monitoring service) managed to crack about 75 per cent of Naval Cipher No. 3 which since June 1941 had routed convoys.51 The Germans were reading Royal Navy codes, although only 10 per cent of the intercepts could be used operationally because of the time taken to decipher them.52 Nonetheless, when the size, destinations and departure times of convoys did become known to the Germans, they could draw up an accurate picture of the whole operation. If they had achieved real-time decryption, as Turing was to do, it could have been potentially as decisive an advantage to the Germans as the cracking of the Enigma code was for the Allies. Instead of recognizing the danger, the Admiralty put the U-boats’ remarkable success in intercepting convoys down to the advanced hydrophone equipment they used, which it was thought could detect propeller noise for over 80 miles. When marvelling at the Germans’ continuing trust in Enigma, therefore, one must also consider the British faith in the Royal Navy’s own compromised codes. Naval Cipher No. 3 was not replaced with No. 5, which the Germans never cracked, until June 1943.
Coincidentally, the worst moment for the Allies in the battle of the Atlantic came in the same month as the Beobachtungdienst cracked Naval Cipher No. 3. On 1 February 1942, OKM (the Supreme Command of the Navy) introduced an extra rotor wheel to the Enigma machines used by U-boats in the Atlantic, thus enormously increasing the number of solutions to any Enigma-encrypted texts. The new code was dubbed Shark at Bletchley, and every effort was made to crack it, initially by producing four-rotor bombes.53 Hitherto the Royal Navy had been able to foil ambushes and divert convoys away from danger areas. Suddenly, for more than ten months – almost for the whole of 1942 – Bletchley was thrust into the dark, its bombes producing only gibberish. With the Navy unable to re-route convoys away from peril, sinkings increased dramatically.
In 1940 U-boats had sunk 1,345 Allied ships totalling 4 million tons for the loss of twenty-four submarines, and in 1941 slightly more, 1,419 totalling around 4.5 million, for the loss of thirty-five. Yet in 1942, with Shark unbroken, U-boats sank 1,859 ships totalling over 7 million tons, albeit for the loss of eighty-six U-boats.54 In November 1942 alone over 860,000 tons of Allied shipping were sunk, 88 per cent of it by more than a hundred submarines that the Germans had at sea.55 Although the church bells were rung to celebrate the victory at El Alamein that month, they could just as well be tolling the news that the Allies were now for the first time in the war losing more tankers than they were building.
Yet salvation was at hand. At 22.00 hours on Friday, 30 October 1942, U-559 was forced to the surface after no fewer than 288 depth-charges were dropped on her by four British destroyers in the eastern Mediterranean. Her captain opened her stopcocks to scuttle the vessel and the entire crew abandoned ship, but Lieutenant Francis Fasson, Able Seaman Colin Grazier and a sixteen-year-old Naafiassistant Tommy Brown (who had lied about his age to join the Navy) from HMS Petard stripped off their clothes and swam over to it.56 Getting into the captain’s cabin, they used a machine gun to break into a locked cabinet and retrieve the codebooks and documents. After Brown had made three journeys delivering these to another party from the destroyer, the U-boat suddenly sank, drowning Fasson and Grazier. Although their gallantry had been up to the standard required for the Victoria Cross, as it was not ‘in the face of the enemy’ as the criteria stipulate they were awarded the George Cross posthumously,