On 1 January 1941, she led four ships of the 13th Destroyer Flotilla as they intercepted a Vichy French convoy near Mellila and seized all four merchant ships of the convoy. A few days later she took part in Operation Excess, a military convoy taking stores to Piraeus and Alexandria. During Operation Grog in early February, the ship escorted the larger ships of Force H as they bombarded Genoa. She then escorted the battlecruiser and the carrier from Gibraltar to West Africa in early March and remained there afterwards. Based at Freetown, the ship escorted convoys through West African waters until July when she was recalled to the Mediterranean to escort the Operation Substance convoy from Gibraltar to Malta in July 1941 Reassigned to the 13th Destroyer Flotilla, "Duncan" remained at Gibraltar and was part of the close escort for the Operation Halberd convoy in late September.