The rapid evolution of radio and radar systems for military use during World War II, and devices to counter them, led to a technological battle that neither the Axis nor the Allied powers could afford to lose. The result was a continual series of thrusts, parries, and counter-thrusts, as first one side then the other sought to wrest the initiative in the struggle to control the ether. This was a battle fought with strange-sounding weapons--"Freya," "Mandrel," "Boozer," and "Window"--and characterized by the bravery, self-sacrifice, and skill of those who took part in it. During the war,...