On 20 July 1805, just three months before the battle of Trafalgar destroyed a combined French and Spanish fleet, the Emperor Napoleon ordered his chief-of-staff to ‘embark everything’ for the invasion of England that he had been dreaming of for two years. ‘My intention is to land at four different points,’ he explained to Berthier, ‘at a short distance from one another… Inform the four marshals there is not an instant to be lost.