The Dieppe Raid is one of World War II's most controversial hours. In 1942, a full two years before D-Day, thousands of men, mostly Canadian troops eager for their first taste of battle, were sent across the Channel in a raid on the French port town of Dieppe. Air supremacy was not secured; the topography of the town and its surroundings - hemmed in by tall cliffs and steep beaches - meant any invasion was improbably difficult; the result was carnage, the beaches turned into killing grounds even as the men came ashore, and whole regiments literally decimated. Why was the Raid ever mounted? No-one appears to have had a clear answer, and no-one afterwards appeared to be clearly accountable, but posterity has been hard on individuals like Mountbatten, who were instrumental in its planning and the decision to go. Was the whole thing even, as has been darkly alleged, expected and even intended to fail, a cynical conspiracy to prove to the Americans, at the expense of so many Canadian lives, the impracticability of staging the Normandy landings for another two years? Now Robin Neillands goes behind the myths to tell what really happened, and why.