The qualification is service between 3 September 1939 and 15 August 1945, being the period of active operations in the war. The necessary service varied for the different forces. For the Royal Navy six months service afloat in areas of active operation were required. For the Army six months service in an operational command were required, but only one days service in Dunkirk, Norway and certain specified commando raids. Airborne troops qualified for the star on participation in an airborne operation provided they had completed two months service in an operational unit. The RAF qualified for an award for any flying qualifications against the enemy, provided that two months service had been completed in operational units; ground crew had to complete six months service in the area of an operational command except for Dunkirk and Norway. For Merchant Navy personnel qualified for six months service afloat with at least one voyage through specified "dangerous waters", which included service during the evacuation from Dunkirk. Irrespective of the six months qualification period, all service personnel qualified who had been decorated or mentioned in despatches, killed in action or died on service, evacuated as the result of wounds or sickness on service, or were evacuated from Dunkirk, Norway, Crete and Greece. Time spend as a prisoner of war also counted. Air crews of fighter aircraft engaged in the Battle of Britain between 10 July and 31 October 1940 were awarded a bar inscribed BATTLE OF BRITAIN. A silver-gilt rose emblem takes the place of the bar when only a ribbon is worn.
