 The Spanish declaration of war on Britain and Portugal in October 1796 made the British position in the Mediterranean untenable.The combined Franco-Spanish fleet of 38 ships of the line heavily outnumbered the British Mediterranean Fleet of fifteen ships of the line, forcing the British to evacuate their positions in first Corsica and then Elba.Early in 1797, the Spanish fleet of 27 ships of the line, which were supposed to join the French fleet at Brest lay at Cartagena, on the Mediterranean Sea, with the intention of sailing to Cádiz as an escort of a 57 merchant convoy, carrying mainly mercury—necessary for gold and silver production—which would eventually enter that Spanish harbour along with warships "Neptuno", "Terrible" and "Bahama", prior to running into the British force.