The Secret War. Spies, Codes and Guerrillas 1939–1945; William Collins, 2016

In The Secret War, Max Hastings presents a worldwide cast of characters and extraordinary sagas of intelligence and Resistance to create a new perspective on the greatest conflict in history. The book links tales of high courage ashore, at sea and in the air to the work of the brilliant 'boffins' battling the enemy's technology. Here are not only the unheralded codebreaking geniuses of Bletchley Park, but also their German counterparts who achieved their own triumphs and the fabulous espionage networks created, and so often spurned, by the Soviet Union. With its stories of high policy and human drama, the book has been acclaimed as the best history of the secret war ever written.