In the spring of 1942 Britain's far-flung empire was in the greatest peril.
North Africa was being overrun by the German Afrika Korps and in south-east Asia the forces of Imperial Japan had captured Singapore and were threatening India.
Only the most urgent reinforcement of both war fronts could prevent disaster.
But Britain's shipping routes to Egypt and India passed the island of Madagascar.
If the Japanese Navy, operating out of Madagascar, could severe Britain's communications with Cairo and Delhi, then the whole of North Africa and the Indian sub-continent would be at the mercy of the Axis Powers.
In a desperate race against time, and under conditions of the utmost secrecy, at Churchill's instigation Britain planned to seize Madagascar, the fourth largest island in the world, before the Japanese could strike.
An overwhelming force was assembled and despatched as part of the largest convoy ever to have left Britain's shores.
Yet the expedition's commanders were faced with not just military but also political obstacles, because the forces occupying the island were not those her enemy's but those of her former ally - France. The Secret Invasion is the first book to examine in detail this crucial campaign which was Britain's largest amphibious assault since the First World War and the first large-scale combined air, sea and land operation Britain had attempted.