The sea battle that British forces under Admiral Horatio Nelson won on October 21, 1805, was then the single most important military victory in the nation’s history since the stand-off with the Spanish Armada in Elizabethan times. It was achieved at a time of national peril, and against considerably superior forces. Not only did it evoke a sense of deliverance at home, but it also confirmed Britain as the pre-eminent world power on the high seas for the next century.