This was a British combined air and sea undertaking to find and destroy the 9,925-ton oiler/supply vessel Brake known to be refuelling, resupplying and rearming U-boats operating in the Indian Ocean in succession to the 7,747-ton Charlotte Schliemann, which had been sunk on 12 February in the Indian Ocean (5/16 March 1944).
In September 1943 Brake had supplied the first group of ‘Monsun’ U-boats operating in the Indian Ocean. Early in March 1944 the escort carrier Battler was operating in the Indian Ocean in the anti-submarine role, and was then teamed with the heavy cruiser Suffolk, light cruiser Newcastle, and destroyers Quadrant and Roebuck, based at Mauritius, as Task Force 67 to intercept and sink U-boats which were known to be using Brake.
Working on the basis of ‘Ultra’ decrypts of the German naval Enigma traffic, it was arranged that a Fairey Swordfish aircraft from the carrier would sight the supply vessel, supposedly by chance to prevent the Germans from supposing that their Enigma codes had been broken, and make an obvious call to a nearby destroyer. The ‘sighting’ was made on 12 March with two U-boats alongside the supply ship. The attack that was now launched managed only to damage one of the U-boats, which nonetheless escaped. The crew of Brake then scuttled their ship on the approach of the destroyer Roebuck, which had joined Task Force 67 on 6 March. The British ships all returned to Mauritius on 16 March.