Much of the detail was due to the personal intervention of Napoleon, who as a soldier rather than a sailor failed to consider the effects of weather, difficulties in communication, and the strengths of the Royal Navy.

A final mopping up action at the Battle of Cape Ortegal on 4 November completed the destruction of the combined fleet, and secured the supremacy of the Royal Navy at sea.

The resumption of hostilities in 1803 led to their revival, and forces were gathered outside Boulogne in large military camps in preparation for the assembling of the invasion flotilla.

[1] The Royal Navy was the main obstacle to a successful invasion, but Napoleon declared that his fleet need only be masters of the Channel for six hours and the crossing could be effected.

[5][6] Napoleon's first plan, put forward in May 1804 for execution between July and September envisaged the break-out from Toulon of 10 ships of the line and 11 frigates under Admiral Latouche Tréville.

[7] While this was taking place Vice-Admiral Ganteaume would sail from Brest with 23 ships of the line and head out into the Atlantic, hopefully drawing the main British Channel Fleet under Admiral William Cornwallis after them.

[8] They would sail to Saint Helena and capture the island from the British, before returning northwards to land at Senegal and stir up trouble in West Africa.

[8] With a combined force of nearly 40 ships of the line, the French would sweep up the Channel to Boulogne and effect the third and final part of the plan, the invasion of England.

[8] He decided to temporarily put his plans for invasion on hold, and developed a new strategy whereby his largely idle fleet could cause trouble for Britain.

[8] Missiessy duly sailed from Rochefort on 11 January with five ships of the line, evaded Vice-Admiral Thomas Graves's blockading force and escaped into the Atlantic.

[9][10] Nelson immediately rushed his fleet to sea, determining that considering the weather and the fact the French had embarked troops, that Villeneuve was heading east, perhaps to attack locations on the Italian coast, or the islands of Malta or Sardinia, or maybe even Greece or Egypt.

[8][13] The error of the frigates leaving the fleet unobserved when they had rushed to report to Nelson meant that he had spent nearly six weeks sailing back and forth across the Mediterranean through heavy seas while the French remained in port.

Napoleon recalled Missiessy once it became clear the Villeneuve had remained trapped in Toulon, and Missiessey began to voyage back to France on 28 March.

[16] The fleet at Brest under Ganteaume was to embark 3,000 troops and sail to Ferrol, where he would chase away Calder's blockading squadron and unite with the French and Spanish forces in the port under Gourdon and Grandallana.

[19] Cotton did not however risk an engagement with night closing, many shoals and with the enemy fleet under the guns of French shore batteries, and chose to merely observe and blockade Ganteaume.

Nelson had been spotted near Barcelona and Villeneuve hoped that by sailing due south from Toulon and passing east of the Balearic Islands, he might avoid the patrolling British.

[20] In reality Nelson was preparing a trap, and having allowed himself to be observed off the Spanish coast, had withdrawn to a position south of Sardinia, hoping that in attempting to avoid the supposed location of the British fleet, Villeneuve would sail straight into them.

[21] Villeneuve put to sea on 30 March, observed by the British frigates Active and Phoebe, and as Nelson hoped, set course to sail between the Balearic Islands and Sardinia.

[20] From Cádiz Villeneuve collected the French 74-gun Aigle and set off across the Atlantic to the West Indies, followed by six Spanish ships of the line and a frigate under Federico Gravina.

Initially reluctant to undertake any large scale assaults on the British possessions in the Caribbean without orders, he was finally persuaded by the Governor of Martinique to attack the British-held Diamond Rock after two weeks of sitting idle at anchor.

Villeneuve was instructed to await the arrival of two extra ships under Rear-Admiral René Magon, and then spend a month attacking and capturing the British colonies in the West Indies.

[24] Villeneuve gathered his forces and pressed northwards towards Antigua, but on 7 June he came across a lightly defended convoy of British merchants, and captured several of them the following day.

[28] Calder duly received an extra five ships of the line under Rear-Admiral Charles Stirling and on 22 July the enemy fleet was sighted heading westwards towards Ferrol.

[d][33][34] Both admirals claimed a victory, with Villeneuve assuring Napoleon that he intended to sail north to rendezvous with Allemand's force from Rochefort, before heading to the Channel.

[36] The following day the combined fleet under Villeneuve, heading for Brest and then on to Boulogne to escort the French invasion forces across the Channel, sighted the three British ships.

'[33] Finisterre and Villeneuve's retreat became the decisive action of the campaign as far as the invasion of England went, for abandoning all hope of fulfilling his plans to secure control of the Channel Napoleon gathered the Armée d'Angleterre, now renamed the Grande Armée, which then left its camps along the Channel coast on 27 August to march east for the Upper Danube valley (via Bavaria) to attack the Austrians in the Ulm Campaign.

Drawing on his own experience from the Nile and Copenhagen, and the examples of Duncan at Camperdown and Rodney at the Saintes, Nelson decided to split his fleet into squadrons rather than forming it into a similar line parallel to the enemy.

[42] Napoleon, increasingly dissatisfied with Villeneuve's performance, ordered Vice-Admiral François Rosily to go to Cádiz and take command of the fleet, sail it into the Mediterranean to land troops at Naples, before making port at Toulon.

[45] Four French ships under Rear-Admiral Pierre Dumanoir le Pelley had escaped Trafalgar and headed north, hoping to reach Rochefort.

Already postponed several times, Villeneuve's defeat at Finisterre and his final failure to link up with the Rochefort and Brest fleets caused Napoleon to abandon his plans in favour of a march eastward.