When Churchill made one of the most inspiring speeches of the 20th century - 'we will fight them on the beaches' - some thought that it was his way of preparing the public for the fall of France. Others heard it as a direct appeal to the Americans. The Prime Minister was speaking in the Commons in June 4 1940, giving thanks for the miracle of deliverance, the harrowing and breathless evacuation of over 338,000 troops - British and French and Belgian - from the beaches and harbor at Dunkirk in the teeth of nightmarish German onslaught. Churchill was determined it shouldn't be labelled a victory. He was already too late. Hours later, broadcaster JB Priestley was to call it 'an absurd English epic'.

The last of the boatloads had returned to Dover in the small hours of June 4th. And the mythologizing had already begun - from euphoric American journalists to the thousands of women who lined up on railway platforms, crowding round exhausted soldiers as if they were movie stars. But was Churchill privately convinced that the Germans were about to successfully invade England?

Those days of Dunkirk, and the spirit, and the image of the indefatigable little ships, are still invoked now whenever the nation finds itself in any kind of crisis. But there is a wider story too that involves a very large number of civilians - from nurses to racing enthusiasts, trades union leaders to dance hall managers, novelists to seaside cafe owners.

And even wider yet, a story that starts in September 1939: of young civilian men being trained for a type of war that was already 25 years out of date; and the increasing suspense - and occasional surrealism - of the Phoney War. The 'absurd epic' of Dunkirk - told here through fresh interviews with veterans, plus unseen letters and archival material - is the story of how an old-fashioned island was brutally forced into the modernity of World War Two.

SINCLAIR MCKAY is the acclaimed author of history and historical true crime including the best-selling The Secret Life of Bletchley Park. HIs previous Aurum titles include Mile End Murder, The Lost World of Bletchley Park, The Secret Life of Fighter Command and The Secret Listeners for Aurum, as well as histories of Hammer films and the James Bond films. He writes features for the Daily Telegraph and the Mail on Sunday and lives in London.