For many, WWII is only what we see regularly on the television, the battle scenes.
There was another war, one of cunning, intelligence, meticulous attention to detail, hours and hours pouring over codes and devices used to encode the secret Nazi plans.
The code breaking centre was Bletchley Park in Buckinghamshire and the high-level and top-secret intelligence produced there, codenamed Ultra, provided crucial support to the Allied war effort. "Sir Harry Hinsley, a Bletchley veteran and the official historian of British Intelligence in World War II, said that Ultra shortened the war by two to four years and that the outcome of the war would have been uncertain without it."
In the following chapters, this book details the years in which this vital effort took place: Codes and War, Bletchley Park, 1940: A Fateful Year, Battle for the Atlantic, North Africa and Italy, The Resistance, Towards Victory in Europe and War in the Pacific.
It is well-written, detailed and fascinating book peopled with intriguing characters many would not associate with winning the war. They did.
PS An excellent book (and later a film) is "Enigma" by Robert Harris