On 27 August, U-570 spent much of the morning submerged. She had been four days at sea and this was to give respite to a crew that was suffering acutely from seasickness (several had been incapacitated). Earlier that morning, she had been attacked by a Lockheed Hudson bomber of 269 Squadron, flown by Sergeant Mitchell and operating from Kaldaðarnes, Iceland. However, the Hudson's bomb-racks failed to release its depth charges during the attack.
The boat surfaced at position 62°15′N 18°35′W at around 10:50 am, immediately below a second 269 Squadron Hudson. Flown by Squadron Leader James Thompson, it was patrolling the area after being summoned by radio by Mitchell. Rahmlow, who had climbed out onto the bridge, heard the approaching Hudson's engines and ordered a crash-dive. Thompson's aircraft reached the submarine before she was fully submerged and dropped its four 250-pound (110 kg) depth charges—one detonated just 10 yards (10 m) from the boat.
The U-boat quickly resurfaced and around ten of the crew emerged. The Hudson fired on them with machine guns, but ceased when the U-boat crew displayed a white sheet. An account of what happened was subsequently given to British naval intelligence interrogators by the captured crew members—the depth charge explosions had almost rolled the boat over, knocked out all electrical power, smashed instruments, caused water leaks and contaminated the air on the boat. The inexperienced crew believed the contamination to be chlorine, caused by acid from leaking battery cells mixing with sea-water, and the engine-compartment crew panicked and fled forward to escape the gas. Restoring electrical power—for the underwater electric motors and for lighting—would have been straightforward, yet there was nobody remaining in the engine compartment to do this. The submarine was dead in the water and in darkness. Rahmlow believed the chlorine would make it fatal to stay submerged so he resurfaced. The sea was too rough for the crew to man their anti-aircraft gun so they displayed a white flag to forestall another, probably fatal, depth charge attack from the Hudson—they were unaware the aircraft had dropped all its depth-charges.
Most of the crew remained on the deck of the submarine as Thompson circled above them, his aircraft now joined by a second Hudson that had been en route from Scotland to Iceland and had broken off its journey to lend assistance. A radio request for help saw a Consolidated Catalina flying boat of 209 Squadron being scrambled at Reykjavík; it reached the scene some three hours later. The German crew radioed their situation to the German naval high-command, destroyed their radio, smashed their Enigma machine and dumped its parts overboard along with the boat's secret papers. Admiral Dönitz later noted in his war diary that he ordered U-boats in the area to go to U-570?'?s assistance after receiving this report and the U-82 responded, but was prevented from reaching the U-570 by Allied air patrols.
The U-570?'?s transmission was in plain language and it was intercepted by the British. Admiral Percy Noble, commander of Western Approaches Command, immediately ordered a small armada of ships to race to the scene. By early afternoon, fuel levels had forced the Hudsons to return to Iceland. The Catalina, a very long-range aircraft, was ordered to watch the submarine until Allied ships arrived. If none came before sunset, the aircraft was to warn the U-570?'?s crew to take to the water, then sink her. The first vessel to reach the U-boat—the anti-submarine trawler HMT Northern Chief in fact arrived at around 10pm, and was guided to the scene by flares dropped by the Catalina. The aircraft returned to Iceland after circling the U-570 for thirteen hours.
The German crew remained on board U-570 overnight; they made no attempt to scuttle their boat as Northern Chief had signalled she would open fire and not rescue survivors from the water if they did this (Northern Chief?'?s captain, N.L. Knight, had been ordered to prevent the submarine from being scuttled by any means) During the night, five more Allied vessels reached the scene, the armed trawler Kingston Agate, two anti-submarine whalers, the Royal Navy destroyer HMS Burwell and the Canadian destroyer HMCS Niagara.
At daybreak, there was a series of signal lamp messages between the Allies and Germans, with the Germans repeatedly requesting to be taken off as they were unable to stay afloat, and the British refusing to evacuate them until they secured the submarine and stopped it from sinking—the British were concerned that the Germans would deliberately leave behind them a sinking U-boat if they were evacuated. The situation became more confused when a small float-plane (a Northrop N-3PB of 330 (Norwegian) Squadron) appeared. Unaware of the surrender, it attacked the U-570 with small bombs and fired on the Northern Chief (which returned fire). No damage was done and Burwell ordered the aircraft away by radio.
The weather worsened; several attempts to attach a tow-line to the U-boat were unsuccessful. Believing the Germans were being obstructive, Burwell's captain, S.R.J. Woods ordered warning shots to be fired with a machine gun, but five of the German crew were accidentally hit and slightly wounded. With much difficulty, an officer and three sailors from the trawler HMS Kingston Agate reached the submarine using a Carley float (a liferaft). After a quick search failed to find the U-boat's Enigma machine, they attached a tow line and carried out the transfer of the five wounded men and the submarine's officers to the Kingston Agate. The remaining crew were taken on board HMCS Niagara, which by this time had come alongside the U-boat.
The ships began slowly sailing to Iceland with the U-570 under tow, and with a relay of Hudsons and Catalinas constantly patrolling overhead. They arrived at dawn on 29 August at Þorlákshöfn. There, the submarine was beached as she had been taking on water and was thought to be in danger of sinking.
This Lockheed Hudson IIIA is in the RAF Museum in Hendon in north London. The RAF Museum is open daily from 10am to 6pm with admission being free. Car parking is available but there is a charge. The nearest underground station is Colindale about a 10-15 minute walk away or a number 303 bus passes both the tube station and museum. The co-ordinates posted are for the entrance to the "Milestones of Flight" hall/exhibition entrance.
The Lockheed Hudson was a military version of the American Lockheed 14 Super Electra airliner and was ordered for the Royal Air Force in June 1938. Hudsons entered service with Coastal Command in 1939. Used extensively over United Kingdom waters on anti-submarine and general reconnaissance duties, Hudsons were also used overseas.
When Hudsons reached obsolescence in the maritime role they were stripped of their armament and re-employed as transports. Some of these aircraft were used in the very hazardous task of carrying Allied agents into and out of Nazi-occupied Europe.
Although never in the forefront of wartime publicity the Hudson can nevertheless claim an impressive list of firsts including:
- The first Allied aircraft to shoot down an enemy while operating from the British Isles.
- The first aircraft to capture a U-boat. U-570 surrendered to a No.269 Squadron Hudson on 27 August 1941.
- The first aircraft equipped to carry airborne lifeboats for air sea rescue duties.
The RAF received just over 2000 Hudsons, 800 of which were purchased, the remainder supplied under American Lend-Lease contracts.