By 1805 "Neptuno" was based at Ferrol, under the command of Captain Don Cayetano Valdés y Flores. There she was joined in late July by ships of the combined Franco-Spanish fleet under Vice-Admiral Pierre-Charles Villeneuve. The combined fleet had recently arrived in European waters from the West Indies, where they had evaded a British fleet under Lord Nelson, but had failed to carry out any attacks on the British colonies in the Caribbean. The fleet, hotly pursued across the Atlantic by Nelson, had been intercepted by another fleet under Robert Calder that had been positioned off Cape Finisterre in expectation of their arrival. Calder captured two of Villeneuve's ships in a confused action, after which Villeneuve withdrew to Ferrol and Corunna. He sailed again on 9 August, taking the Spanish ships he had found in those ports, including "Neptuno", with him, hoping to rendezvous with the French Rochefort squadron under Zacharie Allemand. The hoped-for rendezvous failed: the two French fleets supposedly mistook each other for the main British fleet and, instead of joining, attempted to escape from each other, with Villeneuve fleeing to Cádiz.