A game of birds and wolves : the secret game that revolutionised the war

'Compelling' Sunday Times'A triumph' Daily Mirror'Gripping' Jonathan Dimbleby1941.

The Battle of the Atlantic is a disaster. Thousands of supply ships ferrying vital food and fuel from North America to Britain are being torpedoed by German U-boats.

Britain is only weeks away from starvation - and with that, crushing defeat. In the first week of 1942 a group of unlikely heroes - a retired naval captain and a clutch of brilliant young women - gather to form a secret strategy unit.

On the top floor of a bomb-bruised HQ in Liverpool, the Western Approaches Tactical Unit spends days and nights designing and playing wargames in an effort to crack the U-boat tactics.

As the U-boat wolfpacks continue to prey upon the supply ships, the Wrens race against time to save Britain. With novelistic flair, investigative journalist Simon Parkin shines a light on Operation Raspberry and these unsung heroines in this riveting true story of war at sea. 'History writing at its best' Booklist 'Splendid . . . Simon Parkin's book rips along at full sail and is full of personality and personalities' Sunday Express 'Vivid, engaging' New Yorker