October’s victory at Trafalgar effectively began with the founding of the Third Coalition, an alliance between the French, led by their newly crowned emperor Napoleon Bonaparte, and the Spanish. In early 1805, the naval manoeuvring began that was intended to link up the French and Spanish navies, from Brest in western France to Cádiz in southern Spain. Napoleon’s plan was to lead a diversionary mission to the West Indies with the aim of disrupting Britain’s colonial trade, and then return to the eastern Atlantic to support a land invasion force against Britain some 350,000 strong.

The breaking of Britain’s Atlantic blockade of French and Spanish shipping was effected on March 30. A combined Franco-Spanish naval force headed off towards the Caribbean, with the British – after a false start in the direction of Egypt – in hot pursuit.

Foiled in its West Indian strategy, Napoleon’s expeditionary force returned to Europe. On hearing that the British were substantially increasing their strength, the emperor ordered a sizeable contingent of French and Spanish ships to muster in the Mediterranean. His chief admiral, Pierre de Villeneuve, was unsure of the strategy, but was browbeaten into compliance by threatened withdrawal of his command for cowardice. Bad weather meant that Villeneuve’s first attempt to enter Mediterranean waters had to be aborted, during which time Nelson’s forces had time to head for Gibraltar and effectively close off his approach.

After a waiting game of several days, during which the British fleet lay low on the horizon some 50 miles distant, Villeneuve’s forces were seen to hoist their topsails in preparation to move out of Cádiz harbour. Villeneuve knew that he had in fact already been sacked, and was also aware that some of Nelson’s ships had put in at Gibraltar for reprovisioning, thus weakening the British forces. At the first sign of French movement, Nelson issued the command “Prepare for battle”.

The admiral was reportedly calm and in good spirits on the eve of battle, despite telling his youthful midshipmen on the Victory that, although they would no doubt talk of the coming engagement for the remainder of their lives, “I shall not live to know about it myself”. Some of the crew were still young boys. Midshipmen themselves were generally only in their late teens, but there were also six 13-year-olds, four aged 12, and John Doag, a cabin-boy, who was just ten.

The hours leading up to the fighting were passed singing to the ships’ bands, which thundered out Rule Britannia and other patriotic songs for all they were worth. At 11am the crews dined – awkwardly enough as all the tables and benches had been carried down into the hold, so as to minimise the risk of flying splinters during the gunfire.

The battle plans had been laid three weeks earlier in a confidential memorandum to the Admiralty by Nelson. The British forces split into two lines in preparation for engaging the coalition shipping at right angles. At 11.50am, the famous signal was hoisted up the Victory’s main mast: “England expects that every man will do his D.U.T.Y.” – the last word spelt out in flags because the whole word, oddly enough, wasn’t in the Royal Navy codebook.

Tantalisingly, we cannot be sure which side fired the first broadside, but we do know that the first British ship to fire was the Royal Sovereign under Admiral Cuthbert Collingwood. It is difficult to imagine today what the impact of a close-order naval barrage would have been like. The Sovereign’s first delivery, a broadside of double shots, disposed instantly of something like 400 men on the Spanish Santa Ana, putting no fewer than 14 cannon out of service. As was consistent with naval custom, the dead were thrown overboard as quickly as possible. This initial salvo alone caused considerable mayhem, as other coalition ships – closing in to assist the Santa Ana – found themselves firing at each other.

Villeneuve’s ship, the Bucentaure, engaged the Victory. Nelson’s ship lost most of her sails, her wheel and the mizzen-mast under the first volley, as well as 50 men, nearly half of whom were fatalities. Despite this damage, the Victory succeeded in positioning herself astern of the French flagship and unleashed a sustained cannonade that put the Bucentaure completely out of action. In an almost comical but potentially lethal development, the Victory then got its rigging snarled up with that of the French ship, the Redoutable, which led to the crews of the respective ships each trying to board the other vessel, in the line of fire from both sides. The Temeraire, heroine of the famous painting by Turner, came alongside the Redoutable and pulverised her with cannon fire.

As an indication of the unevenness of the contest, the Redoutable was to lose nearly 90% of her 643 crew during this engagement, while the Temeraire and Victory between them lost just over 100. There was to be one especially poignant casualty, though.

At 1.15pm, not much more than an hour after the start of battle, a French sharpshooter on top of the Redoutable spotted a rather obvious target on the Victory’s quarterdeck. The British commander, who had earlier advised one of his men to  follow his lead in wearing silk legwear to make the surgeon’s job easier if he was hit, had also insisted on wearing his full ceremonial regalia. With his stars and medals and braided epaulettes, he presented a mobile but not too demanding target for the skilful sniper. He took a musket-ball in the lower spine.

Nelson was carried four decks below to a midshipman’s berth, where he was attended by both the surgeon and Captain Hardy. He was to survive for another three hours, during which time Hardy brought him the news that the British victory was complete. Dying with his captain’s kiss of both consolation and congratulation on his cheek, Nelson’s final utterance, characteristically, was “Thank God I have done my duty”. The loss was keenly felt. “God bless you!” wrote one crewman in his journal, “chaps that fought like the Devil sit down and cry like a wench!”

In accordance with his wishes, Nelson’s body was not thrown overboard, but carried back to London for a full state funeral. To preserve it on the voyage home, it was placed in a cask which was then filled with brandy, a sentry standing guard over it through the nights. Nelson was buried beneath the dome in St Paul’s Cathedral, his coffin lowered into a sarcophagus originally made for Cardinal Wolsey. His cortege had proceeded through eerily quiet streets. It was said that the rustle of people’s hats as they were removed along the route of the procession sounded like the gentle lapping of waves against the side of a ship.