The Great Siege of Gibraltar was an unsuccessful attempt by Spain and France to capture Gibraltar from the British during the American Revolutionary War. It was the largest battle in the war by number of combatants.
On 16 June 1779, Spain entered the war on the side of France and as co-belligerents of the revolutionary United States—the British base at Gibraltar was Spain's primary war aim. The vulnerable Gibraltar garrison under George Augustus Eliott was blockaded from June 1779 to February 1783, initially by the Spanish alone, led by Martín Álvarez de Sotomayor. The blockade proved to be a failure because two relief convoys entered unmolested—the first under Admiral George Rodney in 1780 and the second under Admiral George Darby in 1781—despite the presence of the Spanish fleets.