In May 1943, Britain’s Royal Air Force 617 Squadron, led by twenty-four-year-old wing commander Guy Gibson, destroyed the Möhne and Eder dams in northwest Germany on an overnight mission that has become a glorious legend of World War II. But in the twenty-first century, bestselling and acclaimed historian Max Hastings urges we should review the Dambusters raid in much more complex shades.

While celebrating the airmen’s heroism as well as the brilliance of Barnes Wallis, the man who invented the “bouncing bombs” used to destroy the dams, Hastings shows how the raid imposed only a temporary disruption on the Nazi war machine rather than the crippling blow British commanders had promised. He assesses the raid’s devastating costs, including the lives of some 1,400 civilians—more than half of them Russian and Polish women forced into slave labor by the Nazis. Hastings also reconsiders the role of Air Marshal Sir Arthur “Bomber” Harris and analyzes the operation’s biggest mistake—the failure to launch a conventional attack on the Germans’ huge post-raid repair operation.

Setting the dams’ raid in the big picture of the bomber offensive and the Second World War, Hastings masterfully recreates one of the most extraordinary episodes in global military history.