Most people think that England's last war with France involved point-blank broadsides from sailing ships and breastplated Napoleonic cavalry charging red-coated British infantry. But there was a much more recent conflict than this. It went on for over two years and cost several thousand lives. Under the terms of its armistice with Nazi Germany, the unoccupied part of France and its substantial colonies were ruled from the spa town of Vichy by the government of Marshal Philip Petain, the victor of Verdun, one of the bloodiest battles of the First World War. Between July 1940 and November 1942, while Britain was at war with Germany, Italy and ultimately Japan, it also fought land, sea and air battles with the considerable forces at the disposal of Petain's Vichy French. When the Royal Navy sank the French Fleet at Mers El-Kebir almost 1,300 French sailors died in what was the 20th century's most one-sided sea battle. British casualties were nil. In the House of Commons, MPs greeted Churchill's brutal resolve not to risk the warships of their very recent ally falling into German hands with cheers and threw their order papers in the air. It is a wound that has still not healed, for undoubtedly these events are better remembered in France than in Britain. Despite the appalling losses on both sides, the war the British and eventually the Americans fought against France in 1940-42 has never been written about as an entity. An embarrassment at the time, its maritime massacre and the bitter, hard-fought campaigns that followed rarely make more than footnotes in accounts of Allied operations against Axis forces. Until now.