Engineers of Victory: The Problem Solvers Who Turned the Tide in the Second World War by Paul Kennedy Page A
Authors: Paul Kennedy
Tags: General, History, World War II, Military, Political Science, International Relations, Technology & Engineering, Marine & Naval
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smoke), or an aircraft or ship catching sight of a distant U-boat. But, once seen, a U-boat could of course submerge out of sight. And a German submarine could, through newer acoustic equipment, hear the welcome sound of the screw propellers of an oncoming convoy, or the more alarming sound of a fast-approaching corvette. To the U-boat’s opponents also, sonar remained the key acoustic instrument for locating another man-made device under the waters. Yet water temperatures could differ vastly from place to place, creating acoustic barriers, and grinding icebergs nearby were a nightmare to detection engineers. Above all, Doenitz’s recognition—arising from his own experiences as a First World War submariner—that U-boats could neutralize Allied sonar simply by attacking on the surface gave the Germans a great advantage. A pack of eight or ten or twenty submarines, creeping on the surface toward a convoy in the moonlight, or a single U-boat, picking off American freighters as they steamed along the floodlit Florida coast, simply dumfounded
all
underwater detection systems. Sonar could work well, but only when the conditions were right.
Doenitz’s altered strategy meant that the U-boats had to be identifiedat the surface, and before they launched their assaults. The convoy escorts had to know where the attackers were, how far away they were, how many of them there were, and what their line of attack was. If all that was known, the defense of the merchantmen could be undertaken. The submarines could be countered and, with the right weaponry, driven off, perhaps sunk.
It was not really until 1943 that the Allied navies possessed increasingly effective surface-detecting systems, the first of which was the tactical HF-DF radio-beam identifying mechanism mentioned earlier, but there was also the Admiralty’s invaluable long-range tracking system, which allowed Doenitz’s own messages (if decrypted in time) to be read. This type of direction finder had first been set up early in the war on the east coast of England, to locate German radio senders on the other side of the North Sea. It was not too difficult to reduce the size of the apparatus and move it onto individual warships by mid-1943. “Huff-Duff,” as the Allied sailors fondly called it, was relatively simple and reliable, and it worked well at the ranges that mattered. It could pick up a U-boat’s radio signals close by, and thus bring an escort to the threatened flank for a counterattack, but it could also detect the submarine’s radio traffic as much as 15 miles away, thereby allowing the redirection of the convoy and/or the summoning of additional Allied naval and aerial support by the Admiralty, which was reading the long-range enemy messages. Even now, it seems rather remarkable that Doenitz allowed his U-boat commanders to chatter so much, although he himself was guilty of the same sin. While the actual messages might not be understood by the Allies until Bletchley Park decrypted them, the location of the transmitting submarine near a convoy was easily identified. When an Admiralty plotting team picked up reports from its escort commanders that, say, eight U-boats were forming into a wolf pack, it could send an alert to British forces in the area. Rohwer, reflecting on the outcome of the critical convoy battles of March 1943, identifies HF-DF as “decisive.” 34
Centimetric radar was even more of a breakthrough, arguably the greatest. HF-DF might have identified a U-boat’s radio emissions 20 miles from the convoy, but the corvette or plane dispatched in that direction still needed to locate a small target such as a conning tower, perhaps in the dark or in fog. The giant radar towers erected along thecoast of southeast England to alert Fighter Command of Luftwaffe attacks during the Battle of Britain could never be replicated in the mid-Atlantic, simply because the structures were far too large. What was needed was a miniaturized version, but creating
all
underwater detection systems. Sonar could work well, but only when the conditions were right.
Doenitz’s altered strategy meant that the U-boats had to be identifiedat the surface, and before they launched their assaults. The convoy escorts had to know where the attackers were, how far away they were, how many of them there were, and what their line of attack was. If all that was known, the defense of the merchantmen could be undertaken. The submarines could be countered and, with the right weaponry, driven off, perhaps sunk.
It was not really until 1943 that the Allied navies possessed increasingly effective surface-detecting systems, the first of which was the tactical HF-DF radio-beam identifying mechanism mentioned earlier, but there was also the Admiralty’s invaluable long-range tracking system, which allowed Doenitz’s own messages (if decrypted in time) to be read. This type of direction finder had first been set up early in the war on the east coast of England, to locate German radio senders on the other side of the North Sea. It was not too difficult to reduce the size of the apparatus and move it onto individual warships by mid-1943. “Huff-Duff,” as the Allied sailors fondly called it, was relatively simple and reliable, and it worked well at the ranges that mattered. It could pick up a U-boat’s radio signals close by, and thus bring an escort to the threatened flank for a counterattack, but it could also detect the submarine’s radio traffic as much as 15 miles away, thereby allowing the redirection of the convoy and/or the summoning of additional Allied naval and aerial support by the Admiralty, which was reading the long-range enemy messages. Even now, it seems rather remarkable that Doenitz allowed his U-boat commanders to chatter so much, although he himself was guilty of the same sin. While the actual messages might not be understood by the Allies until Bletchley Park decrypted them, the location of the transmitting submarine near a convoy was easily identified. When an Admiralty plotting team picked up reports from its escort commanders that, say, eight U-boats were forming into a wolf pack, it could send an alert to British forces in the area. Rohwer, reflecting on the outcome of the critical convoy battles of March 1943, identifies HF-DF as “decisive.” 34
Centimetric radar was even more of a breakthrough, arguably the greatest. HF-DF might have identified a U-boat’s radio emissions 20 miles from the convoy, but the corvette or plane dispatched in that direction still needed to locate a small target such as a conning tower, perhaps in the dark or in fog. The giant radar towers erected along thecoast of southeast England to alert Fighter Command of Luftwaffe attacks during the Battle of Britain could never be replicated in the mid-Atlantic, simply because the structures were far too large. What was needed was a miniaturized version, but creating
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