In September 1939, Campbell was mobilised for service with the
Royal Air Force (RAF) following the outbreak of the
Second World War. Flying Officer Campbell joined
No. 22 Squadron RAF in September 1940, piloting the
Bristol Beaufort torpedo bomber. Campbell torpedoed a merchant vessel near
Borkum in March 1941. Days later, he escaped from a pair of
Messerschmitt Bf 110 fighters, despite extensive damage to his aircraft. Two days later, on a 'Rover' patrol he torpedoed another vessel, off
IJmuiden. On 6 April 1941 over
Brest Harbour, France, Flying Officer Campbell attacked the German battleship
Gneisenau. He flew his Beaufort through the gauntlet of concentrated anti-aircraft fire from about 1000 weapons of all calibres and launched a torpedo at a height of . The attack had to be made with absolute precision: the
Gneisenau was moored only some away from a
mole in Brest's inner harbour. For the attack to be effective, Campbell would have to time the release to drop the torpedo close to the side of the mole. That Campbell managed to launch his torpedo accurately is testament to his courage and determination. The ship was severely damaged below the waterline and was obliged to return to the dock whence she had come only the day before; she was put out of action for six months, lessening the threat to Allied shipping crossing the Atlantic. Generally, once a torpedo was dropped, an escape was made by low-level jinking at full throttle. Because of rising ground surrounding the harbour, Campbell was forced into a steep banking turn, revealing the Beaufort's full silhouette to the gunners. The aircraft met a withering wall of flak and crashed into the harbour. The Germans buried Campbell and his three crew mates,
Sergeants J. P. Scott DFM RCAF (navigator), R. W. Hillman (wireless operator) and W. C. Mulliss (air gunner), with full military honours. His valour was only recognised when the
French Resistance managed to pass along news of his brave deeds to Britain. ==Victoria Cross citation==