Tuesday, June 30, 2015
While the Second World War resembled the First in that the largest operations of all were waged on one continent, Europe, it also resembled its predecessor in that much of the struggle took place at sea. Until the spring of 1943, submarine warfare probably represented the one method by which Germany could have beaten Britain and forced it to surrender. Conversely, first Britain’s survival and later its ability and that of its larger and more powerful American ally to bring forces to bear against Germany (and Italy) depended on their command of the sea-lanes. Though the Mediterranean was never more than a side theater, here, too, ultimately it was command of the sea that decided the issue. The difference between the two world wars was that, from 1918 to 1939, military aviation developed far more rapidly than warships and merchantmen did. By the time World War II broke out, there was still much argument about how much air support navies required, how it should be organized, and what tasks it should carry out, but the principle that they could not operate without such support had been firmly established.
Having already said something about the Mediterranean, and leaving the Pacific until later, here we shall focus on the Atlantic. In 1939–45, as in 1914–18, without the sea-lanes across the Atlantic, Britain could not exist and would have to surrender sooner rather than later. As in 1914–18, what decided the issue was not so much a Mahan-like encounter between opposing fleets as a long struggle of attrition. That struggle was waged mainly by light naval units and the aircraft that worked with them. As in 1914–18, one of the first things the British did was to revert to the convoy system and to blockade Germany. The Germans on their part used their submarine fleet to impose a counter-blockade.
Seen from the viewpoint of airpower, the struggle was not symmetrical. Wherever they went, the British could and did use aircraft, whether land-launched or carrier-borne, to hunt for German submarines as well as the few other blockade runners, armed and unarmed, that got through. Whatever may be said about relations between the navy and the RAF, cooperation between it and Coastal Command was always exemplary. Meanwhile the German Navy, the Kriegsmarine, owing partly to geography—Britain still stood between it and the open ocean—and partly to its peculiar relationship with the Luftwaffe, did not have nearly as much support from the air. Lacking it, the Naval War Command, the Seekriegsleitung, in Kiel had to rely mainly on RDF (radio direction finding), ELINT, and SIGINT to receive warning that Allied convoys were setting sail, on what course, with what destination, and so on. The ability of submarine captains to locate their prey was greatly, perhaps fatally, reduced. They were forced to spend more time on the surface, where they were vulnerable both to surface ships and to aircraft; coming under attack by the latter, all they could do was either submerge or fire a few shots from the guns some of them started carrying from 1943 on.
From the Allied point of view, the worst moments in the anti-submarine struggle were the first half of 1942 and the first half of 1943. The worst month of all was June 1942, when 700,000 tons of merchant shipping were lost. During both periods, airpower played a critical role in defeating the menace. Based in Scotland, Ulster, Iceland, Greenland, and along the North American coast from Newfoundland to the south, aircraft protected convoys and searched for submarines. Either they attacked those submarines on their own, dropping depth charges on them, or else they acted as the eyes of hunter-killer groups made up of destroyers and other light naval vessels. The more time passed, the more technological progress and the introduction of more long-range aircraft limited the ocean spaces where submarines could operate in relative safety. Some historians claim that this factor was the most important reason why the Allies eventually came out on top. As one German U-boat captain told his commander in chief, successful attacks on convoys were only possible as long as there were no Allied aircraft around.