HMS Devonshire, pennant number 39, was a County-class heavy cruiser of the London sub-class built for the Royal Navy in the late 1920s. The ship spent most of her pre-World War II career assigned to the Mediterranean Fleet aside from a brief tour with the China Station. She spent the first two months of the Second World War in the Mediterranean until she was transferred to the Home Fleet and became flagship of a cruiser squadron. Devonshire took part in the Norwegian Campaign in mid 1940 and evacuated much of the Norwegian Government in June. Several months later, she participated in the Battle of Dakar, a failed attempt to seize the Vichy French colony of Senegal in September. The ship remained in the South Atlantic afterwards and supported Free French efforts to take control of French Equatorial Africa in addition to searching for German commerce raiders.

The County class was a class of heavy cruisers built for the Royal Navy in the years between the First and Second World Wars. They were the first post-war cruisers constructed for the Royal Navy and were designed within the limits of the Washington Naval Treaty of 1922. Such ships, with a limit of 10,000 tons standard displacement and 8-inch calibre main guns may be referred to as "treaty cruisers".