During the Napoleonic Wars, more than twice as many British warships were lost to shipwreck than in battle. The Royal Navy's fleets had to operate in unfamiliar seas and dangerous coastal waters, where navigational ignorance was as great a threat as enemy guns. If Britain was to win the war, improved intelligence was vital.

In this landmark account, Michael Barritt reveals how a cadre of specialist pathfinders led by Captain Thomas Hurd enabled Britain's Hydrographic Office to meet this need. Sounding amongst hazards on the front line of conflict, alert for breaks in weather or onset of swell, these daring sailors gathered vital strategic data that would eventually secure the upper hand against Britain's adversaries. Tracing this pathfinding around Europe, Asia, Africa, and the Americas, Barritt shows how the honing of this skill set revolutionised the British way of war at sea--ultimately securing a lasting naval dominance.