'Bomber Command' by Max Hastings.

Bomber Command's offensive against the cities of Germany was one of the epic campaigns of the Second World War.  More than 56,000 British and Commonwealth aircrew and 600,000 Germans died in the course of the RAF's attempt to win the war by bombing.  The struggle began in 1939, with a few score primitive Whitleys, Hampdens and Wellingtons groping blindly through the darkness over Europe.  It ended 6 years later with 1,600 Lancasters, Halifaxes and Mosquitoes, equipped with the cream of Britain's wartime high technology, razing whole cities in a single night.