Inferno - Max Hastings [179]
In May and June 1942, a million tons of shipping were sunk in United States eastern coastal waters, often by submarines firing torpedoes at vessels silhouetted against the blaze of shore lights. In the year as a whole, 6 million tons went to the bottom. America’s merchant fleet paid dearly for the U.S. Navy’s refusal to join the established Canadian convoy network, and to heed British experience. The Germans began to concentrate “wolf packs” of up to a dozen U-boats to swamp convoy escort groups. Changes of Kriegsmarine ciphers caused periodic “blackouts” of Allied signal interception, with severe consequences for convoys unable to avoid submarine lines. But the Allies progressively raised their game: antisubmarine warfare techniques improved and escort numbers grew; naval radar sets profited from the introduction of cavity magnetron technology; escort groups gained from TBS—Talk Between Ships—voice communication, and even more from experience.
To hunt and sink U-boats, close collaboration between two or three warships was vital: a single ship could seldom drop depth charges with sufficient accuracy to achieve a “kill.” It became difficult for the Germans to operate close to the U.S. or British coasts, within range of air patrols. U-boats could travel fast only on the surface; submerged craft struggled to intercept a convoy. Overhead aircraft forced them to dive, a more effective countermeasure than bomber attacks on the concrete-encased U-boat pens of Brest and Lorient, which cost the RAF much wasted effort. In 1942, the Battle of the Atlantic focused increasingly on a thousand-mile width of sea beyond reach of most shore-based planes. There Dönitz concentrated his forces, and convoys ran the gauntlet for four to six days of peril.
SC104, a typical convoy of thirty-six merchantmen arrayed in six columns, sailed eastward in October 1942 at seven knots—barely eight miles per hour—with an escort of the destroyers Fame and Viscount and the corvettes Acanathus, Eglantine, Montbretia and Potentilla. The first hint of a looming threat came four days after leaving Newfoundland, at 4:24 p.m. on 12 October, when Huff-Duff detected a U-boat radio transmission to starboard; soon afterwards, a second submarine was identified. As night fell, in heavy seas the escorts took up stations ahead and on the flanks of the merchantmen. Conditions were appalling, especially aboard the corvettes, which rolled continuously. Half-drowned bridge crews struggled to keep awake and alert, knowing that even when their four-hour watches ended they were unlikely to find hot food or dry clothing in waterlogged mess decks. If engineers and stokers in machinery spaces were warmer below, they were unfailingly conscious of their diminished prospects of escape if a ship was hit—42 percent of such victims perished, against 25 percent of deck ratings. For weeks on end, strain and discomfort were constants, even before the enemy struck.
That night of 12 October, visibility for convoy SC104 was four miles between snow showers. Just before midnight, a U-boat was detected four miles astern: the Fame turned and raced to launch a radar-guided attack. Just before it reached the U-boat’s position, the pounding of the seas disabled the radar, blinding the destroyer. After a fruitless thirty-minute visual and Asdic search, the Fame returned to its station. Soon afterwards the Eglantine conducted another unsuccessful hunt for a U-boat to starboard. At 5:08