At the Battle of St Vincent, 14 February 1797, Nelson, commanding the 'Captain', 74 guns, swiftly captured the Spanish 'San Nicolas', 80 guns, through the element of surprise. During this feat he met two or three Spanish officers already taken prisoner by his sailors, who handed him their swords. Although the surrender was quick, it was interrupted by firing from the 'San Josef', 112 guns, with whose mizzen starboard rigging a bow anchor of the 'San Nicolas' had become accidentally entangled. Nelson immediately led his men across into the 'San Josef' and took her as well, a capture which rapidly became celebrated (as Nelson himself reported) as 'Nelson's patent bridge for boarding first rates'.

Nelson is shown in the central foreground, standing on the deck of the captured 'San Nicolas'. Facing to the left, he is bare-headed and his left hand is outstretched. He is poised to receive the sword of a Spanish officer who kneels on the deck to support the dying Spanish Commodore Geraldino in his right arm. A priest also kneels just beyond him, and another Spanish officer holds his sword in both hands towards Nelson. Immediately behind Nelson on the left, is Captain Edward Berry, who was with him in the 'Captain' as a volunteer supecargo, looking down on the dying Spaniard. On the right of Nelson, and with his left arm pointing down at the Spaniard is Lieutenant Pearson of the 69th Regiment, some of whom were serving as marines in the 'Captain'. His head is turned away from the viewer and with his right hand and sword he gestures to his men that the ship has struck. In the left background, part of the stern galleries of the 'San Josef' are visible, with Spanish sailors firing from them.

Westall has conveyed the staged effect by employing a dramatic language of gesture and expression. The static tableau in the foreground contrasts with the turmoil being played out in the distance. Nelson's uniform has been closely observed as he stands poised over the dying man, while still-life objects such as a pistol, piece of rope and bloody swords arranged carefully on the deck. A theatrical effect is implied by the rhythmic and exaggerated arm movements of the chief protagonists, particularly Lieutenant Pearson. Rigging is visible in the distance on the right and the action of Spanish sailors firing guns has been suggested by the use of pale colours and sketchier appearance. The composition is both idealized and largely imaginary. By Nelson's own account the Spanish Commodore on the 'San Nicolas' was shot down in the initial rush, which Nelson led and thence straight into the 'San Josef', on whose quarter-deck he received the swords of surrendering Spanish officers. There is no clear evidence that a scene like this took place on either the 'San Nicolas' or the 'San Josef', where the admiral was also mortally wounded, and almost certainly not as regards the former.

This painting was commissioned by John McArthur, as a plate for 'The Life of Admiral Lord Nelson, KB', which he wrote with James Stanier Clarke in 1809, and which was the first major biography of Nelson. Engraved by R. Golding in 1808, it formed part of a series of five painted for the book by Westall, all intended to show Nelson's life as a series of heroic acts. With two by West, also used in the same way (BHC0566 and BHC2905), and Lemuel Abbott's best-known portrait of Nelson (BHC2889), all were presented to Greenwich Hospital in 1849 'by Jasper de St Croix, Esq., and several other patriotic individuals'.

The artist came from an English family of painters and illustrators, and was a book illustrator who turned to painting historical subjects. He was apprenticed in 1779 to John Thompson, a heraldic engraver in London. In his spare time he studied drawing at the Royal Academy Schools in 1785, became an ARA in 1792 and an RA in 1794. His last employment was as drawing master to Princess Victoria. Although his output was prolific, unfortunate picture dealings led him to poverty. The painting is signed and dated,'1806 R Westall RA'.