 Complete the following phrase:  Heavy investment had been made in building up the bomber force, but faith in its potential was beginning to wane, and Harris realised a major propaganda success was vital to demonstrate his belief that bombers could be decisive in defeating the enemy. Harris began pushing for a mass raid using the magic number of 1,000 bombers, although in fact the RAF barely had that many. At last, using every plane available including trainee crews, the RAF raided 