Trafalgar, one of the most famous and strategically significant victories of the age of the sail, was not an isolated event, but rather a culmination of a campaign that began as soon as war was resumed in May 1803, the ultimate aim being the invasion of Great Britain by Napoleon and his allied forces. This book examines the campaign and demonstrates the workings of seapower and reveals that, however great a strategic genius on land, Napoleon never really grasped the principles of British maritime defense.