On 17 Sep 1939, HMS Courageous (50) (Capt W.T. Makeig-Jones, RN) was on anti-submarine patrol about 350 miles west of Lands End, escorted by HMS Inglefield (D 02) (Capt A.G. Talbot, RN), HMS Ivanhoe (D 16) (Cdr B. Jones, RN), HMS Impulsive (D 11) (LtCdr W.S. Thomas, RN) and HMS Intrepid (D 10) (Cdr J.W. Josselyn, RN). At 14.45 hours, the group picked up a distress call from Kafiristan being attacked by U-53 (Heinicke) about 350 miles west of Cape Clear. The destroyers HMS Inglefield (D 02) and HMS Intrepid (D 10) were detached and the carrier launched four Swordfish aircraft, one of them forced the U-boat to dive without damaging it at 17.00 hours. About 18.00 hours, U-29 spotted the carrier group and began chasing it, but had no chance to get into a favorable attack position until the carrier turned into the wind to recover the four Swordfish returning from the search for U-53. She was now heading on a straight course at 18 knots towards the U-boat which attacked only five minutes after the last aircraft landed. At 19.50 hours, U-29 fired a spread of three G7e torpedoes at HMS Courageous (50) and hit her with two of them on the port side abaft the bridge. She almost immediately took a heavy list to port and sank after 17 minutes about 190 miles southwest of Dursey Head, Ireland. The commander, 17 officers and 501 ratings were lost, including 36 RAF service crewmen. All Swordfish aircraft of 811 and 822 Sqdn FAA were lost with the ship.

While HMS Ivanhoe (D 16) attacked U-29 with depth charges, HMS Impulsive (D 11) began to rescue the survivors and was soon joined by the American steam merchant Collingsworth, the British steam merchant Dido and the Dutch steam passenger ship Veendam, which launched 14 lifeboats and also saved the ships log. The rescue work proved difficult due to the heavily oiled sea. Further help arrived when HMS Kempenfelt (I 18) (Capt C. Caslon, RN) and HMS Echo (H 23) (Cdr S.H.K. Spurgeon, RAN) joined HMS Ivanhoe (D 16) in the submarine hunt together with the returned HMS Intrepid (D 10), but the U-boat escaped during the night. Also the two light cruisers HMS Caradoc (D 60) (Capt E.W. Longley-Cook, RN) and HMS Ceres (D 59) (Capt E.G. Abbott, AM, RN) arrived at the scene together with HMS Kelly (F 01) (Capt L.F.A.V.N. Mountbatten, RN), but the cruisers were soon ordered away. Dido had picked up 23 officers and 195 ratings and was escorted to Liverpool by HMS Intrepid (D 10). The survivors rescued by the neutral merchants were transferred to HMS Inglefield (D 02) and HMS Kelly (F 01) and arrived at Devonport on the evening of 18 September.

After this loss and the unsuccessful attack of U-39 (Glattes) on HMS Ark Royal (91) only three days earlier, carriers were withdrawn from such patrols.