At or about 1.15 in the afternoon of 21 October 1805, Vice Admiral Horatio Nelson was struck by a 22-gramme, 15-millimetre French musket round fired down from the mizzen top of the Redoutable, a distance of some 70 feet to HMS Victory’s quarter deck. It nicked the edge of his epaulette, and passed diagonally down, through the material of his coat and into the left shoulder, fracturing the upper part of the scapula or shoulder blade, then the second and third rib. It pierced the left lung, dividing a branch of the pulmonary artery, and emerged to sever the spine, splintering the sixth and seventh vertebrae above and below as it crashed between. The soft lead ball – distorted by collisions with bone – ended its flight embedded in muscle two inches below the right scapula. In this fresh and visceral retelling of the battle of Trafalgar, Paul O’Keeffe traces the course of events both prior and subsequent to that fatal shot.