Kriegsmarine trawlers and three E-boats. One E-boat and one trawler were sunk in the engagement. On 10 September 1940, she attacked invasion barges in Ostend with and . A few days later, the same three ships shelled Boulogne in a sweep along the French coast. At the end of the year, she was deployed to the Western Approaches Escort Force for Atlantic convoy defence. In this role Malcolm was engaged in all the duties performed by escort ships; protecting convoys, searching for and attacking U-boats which attacked ships in convoy and rescuing survivors. In twelve months service Malcolm escorted 29 Atlantic and 3 Gibraltar convoys, of which 10 were attacked and she was involved in two major convoy battles. In February 1941 Malcolm joined the newly formed 8th Escort Group as senior ship, her captain, Cdr C D Howard–Johnston, being Senior Officer Escort (SOE). On 10 May, Malcolm rescued the eleven survivors from , which had been torpedoed and sunk by . They were later landed at Reykjavík. In May convoy HX 126 came under attack, losing 6 ships; Malcolm and 8 EG were sent as reinforcement, repelling further attacks and preventing further losses. During the action was badly damaged and forced to return to base. In June 1941 Malcolm and her group were assigned to HX 133, which had lost five ships in one night. Over the next four days the group fought off further attacks, and on 29 June 1941, Malcolm helped to sink the German U-boat . 45 of her crew were later rescued and interrogated by the Admiralty. On 3 February 1942, she collided with the HMS Burnham. Neither ship was badly damaged and both continued in their convoy defence roles. On 11 August 1942, she was transferred to Gibraltar and assigned to escort the aircraft carrier from Malta after delivering Spitfires to the besieged island. Whilst escorting the carrier, on 12 August, she came under attack by the . The submarine was later rammed and destroyed by . On 7 September her next escort duty was the Arctic convoy PQ 18 to the Soviet Union in which she was leader of the close escort. She arrived in Arkhangelsk on 21 September 1942 after a seven-day running battle, in which 13 ships were sunk, while 3 U-boats were destroyed and 40 aircraft claimed shot down. In October she was in Liverpool to have extra armour plating