<P> The Defeat of the Floating Batteries at Gibraltar (also called The Siege of Gibraltar, The Siege and Relief of Gibraltar or The Repulse of the Floating Batteries at Gibraltar) is the title of a 1791 oil - on - canvas painting by Boston - born American artist John Singleton Copley . It depicts the defeat of the floating batteries at Gibraltar during the Great Siege of Gibraltar . The Governor of Gibraltar, General George Augustus Eliott, is on horseback pointing to the rescue of the defeated Spanish sailors by the British . </P> <P> The painting is based on an attack that took place in Gibraltar on September 13, 1782 . The Great Siege of Gibraltar was an unsuccessful attempt by Spain and France to capture Gibraltar from the British during the War of American Independence . In September 1782 the Spanish formulated a secret weapon known as the Floating Batteries . Designed to fire on Gibraltar at close quarters with deadly accuracy, floating batteries were built of 1 metre (3 ft) - wide timbers packed with layers of wet sand, and were considered fire - proof and unsinkable . The British used heated shot to counterattack these batteries . These "hot potatoes," as they were nicknamed, were pre-heated to furnace temperatures before being fired at the advancing ships . Many were doused but a rogue heated shot could lie smouldering in the bowels of an enemy ship burning a cavity into the wood . Left long enough, these would eventually cause an inferno . </P> <P> American - born John Singleton Copley was commissioned by the City of London in 1783 to depict the victory of the Great Siege which had been won a few months earlier . At over 42.5 square metres (458 square feet), his picture is one of Britain's largest oil paintings . </P> <P> It depicts the Governor General George Augustus Eliott, riding to the edge of the battlements to direct the rescue of the defeated Spanish sailors by the British . General Eliott, created Lord Heathfield in 1787, was also portrayed by Sir Joshua Reynolds (link), currently in the National Gallery, London and Copley himself (link), currently in the National Portrait Gallery; both pictures were painted in 1787 . Two of Copley's preparatory sketches for the painting are in the Metropolitan Museum of Art . </P>

The siege and relief of gibraltar 13 september 1782