 Complete the following phrase:  After their defeat in the Battle of the Heligoland Bight in 1939, the British abandoned daylight raids in favour of night bombing. The appointment of Arthur Harris, Air Officer Commanding AOC Bomber Command changed the nature of the night war. Area bombardment became the tactical method of destroying a target after the damning Butt Report in 1941. The result of improved navigational aids and new heavy bomber designs, the British carried out destructive air attacks on German cities, beginning with the 