A few days later, on 14 September, two Blackburn Skua dive-bombers from the aircraft-carrier HMS Ark Royal attacked the U-30 which had surfaced alongside the freighter Fanad Head while a German boarding party searched for food (the U-boat rations had gone mouldy) prior to opening its sea valves to sink it. Again the anti-submarine bombs exploded in the air, bringing down both planes. The U-boat crew, commanded by Kapitänleutnant Lemp, rescued two of the aviators and then dived with them as prisoners. The next day another Anson was damaged by its own bombs without causing damage to the target. A year later, on 25 October 1940, three Hudson bombers from 233 Squadron subjected the U-46 to a concentrated attack in which one 100-lb anti-submarine bomb scored a direct hit. The U-boat’s pressure hull remained intact and the vessel managed to get back to port.
It is no surprise to learn that the first U-boat sinking from the air was carried out by Bomber Command using ordinary 250-lb general purpose bombs. A Bristol Blenheim on an armed reconnaissance went dangerously low to deliver a determined attack upon U-31, which on that day, 11 March 1940, was undergoing sea trials off Heligoland Bight. One, perhaps two bombs, hit the hull. Everyone aboard, including many dockyard workers, died though the hull was salvaged, refitted and went back into action. At last, a month later, a Fairey Swordfish flying off HMS Warspite did manage to score with two 100-lb anti-submarine bombs, sinking the U-64 at anchor.
In view of the ineffectiveness of the anti-submarine bombs, the airmen decided to throw at the enemy the only other anti-submarine weapon available: the depth charge designed in the First World War. This thin metal drum, packed with explosive, had an adjustable fuse which detonated according to water pressure. A nose and tail were fitted and it was dropped with reasonable success on practice targets, although only large aircraft could carry the depth charge since it weighed 450 lb. Altogether different to the bomb, it was designed to go into the water alongside the target rather than strike it (those that hit a submarine seldom exploded), and since the explosion took place underwater it posed far less danger to the airmen. But such depth charges were not in general supply until the summer of 1941.
In 1939 both sides were acutely short of large long-range aircraft. The Luftwaffe had been forced to use a civil airliner, the Fw 200C Condor, a beautiful machine that in August 1938 had flown non-stop from Berlin to New York and back at an average speed of 205 mph. Pressed into use for long-range maritime reconnaissance, the Condor was not rugged enough for the rigours of military flying.
The RAF had the equally fine Short Sunderland flying boat, a four-engined machine with a crew of anything up to 13. It came complete with kitchen and beds. Although it looked like the same manufacturer’s civil flying boat, this aircraft was built to a military specification and so was much better suited to a military role than the adapted Condor. One Sunderland, forced down on to a very rough Atlantic, with winds gusting up to 100 mph, remained afloat for the nine hours that it took HMAS Australia to arrive and rescue its crew.
The Sunderland had won headlines a few days after war began when two of them landed on the sea and rescued the 34-man crew of a torpedoed tramp steamer. Any flying boat – let alone one with a crowd of unscheduled passengers – is difficult to unstick from open water. It was a remarkable feat of airmanship, and seamanship too. With a range of almost 3,000 miles at 134 mph the Sunderlands would no doubt have seriously depleted the U-boat flotillas if suitable bombs or depth charges had been available in the early days of the Atlantic battle.
Since 1936 the United States navy had been using as their patrol plane a reliable two-engined flying boat which the RAF called a ‘Catalina’ after an island near Consolidated’s San Diego plant. The RAF ordered 30 of these aircraft in 1939 and they began arriving in 1941. It was one of these flying boats that sighted the Bismarck on 26 May 1941. The pilot who shadowed the German battleship was actually on a check flight with a US navy instructor aboard.11 They were flying out of Lough Erne in Northern Ireland, which in great secrecy had already been allotted funds and materials for conversion to a US naval air base. The official account of the interception seems to have had some expletives deleted:
I was in the second pilot’s seat when the occupant of the seat beside me, an American, said ‘What the devil’s that?’ I stared ahead and saw a dull black shape through the mist which curled above a very rough sea. ‘Looks like a battleship,’ he said. I said: ‘Better get closer. Go round its stem.’ … two black puffs appeared outside the starboard wing tip. In a moment we were surrounded with black puffs. Stuff began to rattle against the hull. Some of it went through and a lot more made dents in it … The only casualties occurred in the galley, where one of the crew who was washing up the breakfast things dropped two china RAF plates and broke them.12
During the Bismarck surveillance a Catalina created a Coastal Command record of 27 hours of continuous reconnaissance. The Cat was remembered by those who flew it for its particularly good auto-pilot, which made it possible to endure long hours at the controls of this heavy machine – patrols regularly lasted 17 hours – and meant there could be an extra pair of eyes watching for U-boats. Later, at the direct instruction of President Roosevelt, these flying boats were joined by another Consolidated aircraft: the B-24J Liberator, a four-engined aircraft with extra fuel tanks fitted. Able to carry antenna, radar sets, bombs, depth charges and even searchlights, the Liberator played a vital part in narrowing that mid-Atlantic ‘gap’.
Consolidated Catalina flying boat
Long-range flying was pioneered during the war by hastily trained young men plucked from civilian jobs. RAF Sunderlands flew a thousand miles out over the Atlantic, and did it day after day. When America entered the war Boeing B-17 Flying Fortress pilots, at the end of their US army air force training, flew their Forts to Britain. It was a Catalina delivered to Australia that made the third air crossing of the Pacific. In normal times these events would have made newspaper headlines.
Maritime patrol aircraft needed a very long range, for they had to reach the convoys far out in the ocean before work could start. Once in place, their chief value arose from the fact that U-boats had to remain below when aircraft were present, or risk being bombed. Even a slow 7-knot convoy would soon outdistance a submerged submarine, and a submerged submarine could be detected on asdic.
The start of a convoy’s trouble came when one of a rake of submarines spotted smoke, began trailing it at a distance, and then transmitted signals to bring others. A U-boat forced to submerge might well lose contact with the convoy and would have to cease transmitting.13
An unforeseen dimension of the encounter between aircraft and submarine was the fact that land-based aircraft could not pick up survivors in the sea. This brought an unexpected outcome in August 1941 when a Lockheed Hudson bombed U-570 in the open sea to the south of Iceland. The U-boat was one of the large long-range Type IXC vessels that were