'Acumen' was a British naval undertaking against U-boats passing through Norwegian coastal waters with the object of facilitating the 'Golden' passage of the JW.62 outbound Arctic convoy (29 November/18 December 1944).
As the German battleship Tirpitz had been sunk in 'Catechism' and thereby eliminated from the equation of Allied and German naval strengths available for operations in Arctic waters, there was no need for a battleship covering group to be provided by Admiral Sir Henry Moore’s Home Fleet. The JW.62 convoy thus departed Loch Ewe on the west coast of Scotland on 29 November with 30 laden merchant ships and one rescue vessel, escorted by the 8th and 20th Escort Groups, which included the destroyers Beagle, Bulldog, Keppel and Westcott, sloops Cygnet, Lapwing and Lark, corvettes Allington Castle and Bamborough Castle, and Free Norwegian corvettes Tunsberg Castle and Eglantine on transfer to Murmansk.
The additional covering force which left British waters on 1 December, under the command of Rear Admiral R. R. McGrigor, comprised the escort carriers Campania and Nairana, light anti-aircraft cruiser Bellona, and destroyers Caesar, Cambrian, Caprice and Cassandra (1st Division of the 7th Destroyer Flotilla), Obedient, Offa, Onslaught, Onslow, Oribi and Orwell (17th Destroyer Flotilla), frigates Bahamas, Somaliland, Tavy and Tortola shielding the two escort carriers, and frigates Loch Alvie, Monnow, Nene, Port Colbourne, St John and Stormont of the Canadian 9th Escort Group.
This escort force left JW.52 on arrival at the mouth of the Kola inlet, and then provided support for the RA.62 inbound convoy. On 13 December two Fairey Swordfish attack aircraft from Campania's No. 813 Squadron located and used depth charges to sink Oberleutnant Diether Todenhagen’s U-365, which had earlier torpedoed and damaged Cassandra.