Claude Grahame-White & Harry Harper 
The Aeroplane in War [EPUB ebook] 

It is our aim, in this book, to show what the war aeroplane has done, and can do. At present, its work has been confined to scouting. But it has other, and grimmer possibilities. It can, and without doubt will, be used as an engine of destruction—not by means of the bomb-dropping attacks of a few aeroplanes, but by the organised onslaught of large squadrons of weight-lifting machines, which will be able to rain down tons of missiles over any given spot.
Thus—probably waged with light guns firing explosive shells—the next great war will begin, not on earth, but several thousand feet in the air.
Claude Grahame-White.
Harry Harper.
London, 1912.