Early in 1797, a Spanish fleet of 27 sail of the line lay at Cartagena, with the intention of joining the French fleet at Brest. Adiral Sir John Jervis, commander of the British Mediterranean fleet, aimed to prevent this and with 15 sail of the line, plus frigates, he repaired to rendezvous with Rear-Admiral William Parker off Cape St Vincent. Don José de Cordova and the Spanish fleet left Cartagena on 1 February and might have reached Cadiz safely but for a fierce Levanter, the easterly wind, blowing between Gibraltar and Cadiz. This pushed the Spanish into the Atlantic and by 13 February, close to the British force. Early on the 14th, Jervis learnt that the Spanish fleet was 35 miles to windward.

This picture concentrates on the dramatic incident of the capture of the ‘San Nicolas', 80 guns, and the 'San Josef', 112 guns. In the left central foreground the 'Captain', 74 guns, in starboard-bow view, commanded by Commodore Horatio Nelson, is alongside the 'San Nicolas', also starboard view. Soldiers and marines pour onto the Spaniard's decks. Beyond the bow of the 'San Nicolas' the stern of the 'San Josef', in starboard-quarter view, is accidentally foul of (attached to) the 'San Nicolas'. Sailors fire from the stern galleries of the 'San Josef' down on to the British in the waist of the 'San Nicolas'. The fact that the two Spanish ships were hooked together prompted Nelson to lead a boarding party through the stern galleries of the 'San Josef', capturing that too, a course of action that became known as ;Nelson's patent bridge for boarding first rates'. The whole incident is what first made Nelson a public celebrity, rather than just known in the Navy, and earned him a knighthood: his promotion to rear-admiral shortly afterwards was a routine one by seniority rather than as a direct result. In the right foreground is part of the 'San Josef's' mizzen-mast, topmast and cro'-jack yard, with people clinging to them. In the left foreground people, tossed by the waves, are clinging to the 'Captain's’ foretopmast and yard.Further left, a rescue boat is pulling in. Beyond the stern of the 'Captain' is the stern, starboard-quarter view, of a British three-decker and in the left of the picture a British two-decker nearly bow on. In the right background, beyond the bow of the 'San Josef', is the starboard bow of a British three-decker, and beyond her the bow of a British two-decker. On the right of the picture is a British two-decker almost stern-on, flying the red ensign.

Allan, the artist, was a notable Scotish painter and President of the Royal Scottish Academy. Given that he was not primarily a marine painter, this canvas is an unusual and fine example of what he could do in that line. It is dated 1845 and may be one shown as no. 391 at the RSA exhibition of 1847 (the 50th anniversary of the battle) as 'Commodore Nelson boarding the San Nicolas at the Battle of St Vincent 14 February 1797' which is the same one under which it was previously catalogued when in the Naval Gallery of Greenwich Hospital from 1860. However, in 1847 it was noted as being lent by the Admiralty and there is as yet no confirmation tha it (or any other version) was ever in their possession. The apparently private donor who gave it to Greenwich Hospital in 1860 was H.C. Blackburn.