The period of warfare when it was possible for Gibbon to speak of forces as being employed in ‘temperate and undecisive contests’ came to an end in the era of Nelson and Napoleon. Wars in which decisive victories were won were now fought on an unprecedented scale. Nelson, who embodied the art of the admiral, and Napoleon who embodied that of the general, agreed on the fundamental tactical principle of the concentration of force because under prevailing conditions, as Nelson said, ‘Only numbers can annihilate’. Moreover the tactical freedom which he enjoyed now that the old Fighting Instructions had been replaced by the new signal books (notably Sir Home Popham's Marine Vocabulary) enabled him to improvise brilliantly as he did at the battle of the Nile, or plan with minute care an unusual mode of attack, as at Copenhagen and Trafalgar. His successes were made possible by the high number of officers of unusual ability in the British navy at that date. The fleets which he led to victory had been trained by Lord St Vincent, and his ‘band of brothers’ had already seen service in the War of American Independence. A new spirit of leadership atoned for whatever shortcomings there were in the administrative machine, whereas the efficiency of his enemies was impaired by their lack of combat experience and the consequences of earlier revolutionary excesses.

If sea power under sail may be said to depend on the three factors of an efficient battle fleet, a flourishing merchant marine, and overseas bases from which attacks on colonial possessions could be launched, Britain was in a favourable position at the start of the war.