"Devonshire" was in the Mediterranean when the war began in September 1939 until she was transferred to the Home Fleet some months later. After the armed merchant cruiser was sunk by the German battleships and on 23 November, "Devonshire" and the battleships and sailed from the Clyde on a fruitless attempt to find the German ships. In March 1940 she became the flagship of the 1st CS, and flew the flag of the future First Sea Lord, Vice-Admiral John H. D. Cunningham. During this time the squadron was tasked to cover Scotland, the Faeroe Islands and Iceland. As part of the Allied plans to occupy parts of Norway and interdict the iron ore traffic from Narvik to Germany (Operation Wilfred and Plan R 4), "Devonshire" and the rest of the squadron were assigned to ferry British troops from Rosyth to Stavanger and Bergen and to be ready to sail on the morning of 8 April, but these plans were partially preempted by the German invasion that same day.