A remarkable mission was carried out on August 27, 1941, by Lockheed Hudsons of the RAF Coastal Command’s 269 Squadron: they seized a U-boat without the aid of surface ships
Few believed the U-boat would be as lethal as it turned out to be at the beginning of World War II. However, sonar-equipped escorts and convoys soon proved insufficient to protect the Allies’ merchant ships, leaving the RAF’s anti-submarine warfare aircraft as its sole offensive weapon. The first two years of the war were the most challenging for RAF Coastal Command.
They were the only force that could engage the U-boats despite being severely resource-constrained, flying obsolete aircraft, and using frequently ineffective weapons, as shown on August 27, 1941, when Lockheed Hudsons of 269 Squadron carried out an incredible mission that was never repeated during the war: they captured a U-boat without the aid of surface ships.
U-570 was on its first war patrol. The U-boat was three days away from Trondheim, and according to Mark Lardas’ account in his book Battle of the Atlantic 1939–1941, everything was going wrong. The air compressor wasn’t working correctly. The diesel’s untuned condition caused unpleasant vibrations. After U-570 hit bottom while traveling to Trondheim, the hydrophones (passive listening gear) were knocked out. The crew was also seasick. It was easy for the other crew members to become seasick surrounding a seasick sailor in a cramped U-boat who was throwing up into buckets all around them.
At 10:50 a.m., it came to the surface right as a patrolling Hudson struck it with depth charges. Although the attack was quite loud, U-570 was not substantially damaged. However, its crew was inexperienced and seasick, and its captain, Hans-Joachim Rahmlow, lacked experience. Both were immediately terrified. The crew sealed off the bow because they believed seawater interacting with battery acid was causing the forward portion of the ship to fill with chlorine gas. The captain then gave the order to surface and abandon the ship. The crew swarmed onto the deck and conning tower in a flash.
The crew of U-570 waved white shirts and boards as they surrendered, refusing to dive into the icy waters of Iceland and being strafed by the Hudson that had initially attacked it. The Hudson’s pilot paused firing and requested that more planes join him. These included a Consolidated Catalina from 209 Squadron, which had sunk U-452 two days previously, and a second Hudson (equipped with depth charges). The skipper of the U-570 ordered the secret gear aboard the U-boat to be thrown overboard and broadcast an unencrypted radio message asking for assistance. The Enigma code machine was one of those.
U-boats and surface ships quickly arrived at the area in response to this radio call. The U-boats were kept at bay by the swarm of planes, and the prize was taken by an armed trawler when it arrived at 2200 hours, just before dark. The British were able to transport U-570 to Reykjavik safely despite an attack by a Norwegian-manned Northrup that was unaware it had been surrendered the previous morning.
The Type VII submarine U-570 proved to be an intelligence gold mine, offering a lot of knowledge about it even after the secret papers and Enigma machine were destroyed. Its Enigma machine’s destruction wasn’t a loss either. One was already in Britain after being taken from U-110 by surface combatants. The crew of the U-110 was unaware that the Enigma machine had been taken; after its top-secret equipment was taken, the ship sank while being towed to Iceland.
The Germans were unable to hide U-570’s capture, thus having its skipper radio that the code equipment had been destroyed prevented them from learning that the British were deciphering their Enigma code. After operation testing was completed, U-570 was eventually commissioned into the Royal Navy as HMS Graph and spent the remainder of its operational career hunting U-boats.
Battle of the Atlantic 1939-41 is published by Osprey Publishing and is available to order here.
Photo by Crown Copyright
