Horatio Nelson had a problem. The British admiral’s fleet was outnumbered at Trafalgar by an armada of French and Spanish ships that Napoleon had ordered to disrupt Britain’s commerce and prepare for a cross-channel invasion. The prevailing tactics in 1805 were for the two opposing fleets to stay in line, firing broadsides at each other. But Nelson had a strategic insight into how to deal with being outnumbered. He broke the British fleet into two columns and drove them at the Franco-Spanish fleet, hitting its line perpendicularly. The lead British ships took a great risk, but Nelson judged that the less-trained Franco-Spanish gunners would not be able to compensate for the heavy swell that day and that the enemy fleet, with its coherence lost, would be no match for the more experienced British captains and gunners in the ensuing melee....