The ever-controversial subject of Bomber Command's strategic air offensive against German cities, and industrial targets, in a series of 35 maps extracted form the four volume official history of the air offensive against Germany.
Britain's bombing offensive, one of the few weapons available to it in the dark early days of the war, escalated after the battles of France and Britain and the opening of the Luftwaffe's Blitz on Britain, from precision targets to mass area bombing of cities.
This is a very useful map collection that should be part of every serious WW2 aviation scholar's collection.