Horatio Nelson (1758 - 1805), later vice admiral Horatio, Viscount Nelson, was a distinguished officer of the Royal Navy. He was a key commander in the Napoleonic Wars, killed in action at the culminating sea action, the Battle of Trafalgar. He was an aggressive tactician, whose insights, appropriate for the time, were fossilized into inappropriate rigid doctrine, but eventually put in proper and useful context.
England expects every man will do his duty — Nelson's signal to the fleet at the start of the Battle of Trafalgar
The "Nelson touch" has become a well-recognized term for a naval officer of exceptional ability, with both technical insight and inspirational leadership.
There had long been, in the Royal Navy, documents and publications called Fighting Instructions.  Nelson's specific instructions at Trafalgar contravened existing doctrine, but less insightful admirals then made them standard operating procedure. They were intended for a specific tactical situation, with a particular set of aggressive and trusted commanders sharing a common tactical philosophy.
Nelson was married, but conducted an open and notorious affair, of many years, with Emma, Lady Hamilton. His wife remained devoted, but Lady Hamilton was his great love.
This was the decisive naval engagement of the war, irretrievably breaking the French Navy. Prior to the battle, he had mapped out an unconventional tactical plan, putting his force into what was considered a vulnerable position, but in which he believed, correctly, that the higher skill level of the Royal Navy would prove decisive. Unfortunately, a number of later successors rigidly applied that plan in situations where the specific conditions of Trafalgar did not apply.
On board his flagship, HMS Victory, Nelson died of a gunshot wound received after he knew Britain had won the battle. While treatment was far beyond the capabilities of early 19th century medicine, there have been interesting contemporary medical analyses. 
Effect on doctrine
Fiction based on Nelson
- Horatio Nelson (1758 - 1805), BBC News
- Julian S. Corbett (15 September 2005), Fighting Instructions, 1530-1816; Publications Of The Navy Records Society Vol. XXIX., Project Gutenberg
- Robert K. Massie (1991), Dreadnought: Britain, Germany and the Coming of the Great War, Ballantine, ISBN 0-345-37556-4, pp. xiii-xvi
- William C. Hanigan & Chris Sloffer (2004), "Nelson's Wound: Treatment of Spinal Cord Injury in 19th and Early 20th Century Military Conflicts", Neurosurg Focus 16 (1)
- Albert B. Lowenfels, William A. Liston David Burris (2008), "Historical Perspectives in Surgery: The Case of the Fearless Mariner With a Mortal Chest Wound", Medscape General Surgery