By 1805, Napoleon's Armee d'Angleterre had been encamped at Boulogne for months, drilled and ready. The only obstacle was the English Channel and the Royal Navy that patrolled it. The plan required French Admiral Pierre-Charles Villeneuve to escape the British blockade at Toulon, collect Spanish allies at Cadiz, and lead the combined fleet to Martinique. There, reinforced by Admiral Ganteaume's squadron from Brest, the fleet would race back across the Atlantic, clear the Channel, and buy the invasion army a few crucial days to cross. Villeneuve sailed on March 29 with eleven ships of the line. He evaded Nelson, passed Gibraltar, picked up six Spanish ships at Cadiz, and reached Martinique by May 12. But Ganteaume never arrived -- his fleet remained trapped at Brest. When Villeneuve learned Nelson had followed him to the Caribbean, he abandoned the mission and turned for home.

Vice Admiral Robert Calder received intelligence on July 19 that the Franco-Spanish fleet was approaching. He lifted his blockade of Ferrol and Rochefort and positioned his fifteen ships of the line off Cape Finisterre. The fleets sighted each other around 11:00 on July 22, but hours of maneuvering consumed the afternoon. Action began at 17:15 as the British bore down through thickening fog. What should have been a line engagement dissolved into a confused melee. HMS Malta, commanded by Sir Edward Buller, found herself surrounded by five Spanish warships. In a fierce fight that killed five and wounded forty of her crew, Malta battled her way out, sending devastating broadsides from both sides simultaneously. By 20:00, Buller had forced the 80-gun San Rafael to surrender and then seized the 74-gun Firme. Calder signaled to break off at 20:25, though gunfire continued for another hour in the darkness.

Dawn on July 23 revealed the fleets 27 kilometers apart. Calder held two prizes but faced a dilemma. He was outnumbered twenty ships to fifteen, his Windsor Castle and Malta were damaged, and he feared that the French squadrons at Ferrol and Rochefort might sortie and join Villeneuve. He chose caution over aggression and withdrew northeast. Villeneuve, for his part, claimed the light breeze prevented him from closing for attack. On July 24, the wind shifted to give the Franco-Spanish fleet the advantage of the weather gauge -- the ideal position for an assault. Villeneuve turned away. British losses totaled 41 killed and 162 wounded. The Franco-Spanish fleet lost 476 killed and wounded, with 800 more reported ill, and over 1,200 sailors and marines were captured aboard the two surrendered ships.

Both commanders paid for their timidity. Calder was court-martialed and severely reprimanded for failing to renew the battle. He never served at sea again. Villeneuve's consequences were more far-reaching. He limped into Vigo to refit, then slipped into A Coruna, where Napoleon's orders demanded he proceed immediately to Brest and Boulogne. Instead, perhaps believing false reports of a large British fleet in the Bay of Biscay, Villeneuve sailed south to Cadiz, arriving August 21. Napoleon was furious. "Gravina is all genius and decision in combat," he wrote of the Spanish admiral. "If Villeneuve had had those qualities, the battle of Finisterre would have been a complete victory." The withdrawal to Cadiz killed the invasion plan. The Armee d'Angleterre was renamed the Grande Armee and marched east to fight Austria and Russia. Villeneuve's fleet remained bottled up until October 21, when it sailed out to its destruction at Trafalgar.