In the early days of September 1782, the largest action of the whole of the American War of Independence was about to start. Despite the battle of Yorktown, which sealed US independence, being nearly a year before, the war was not quite over, and this revolutionary battle would have a number of unique features. Firstly, not a single American was taking part, and secondly, it was happening not in the New World, but around Gibraltar in the Mediterranean.

When the Revolutionary War broke out, the Americans had found themselves with some unexpected allies in the form of the ‘Bourbon Alliance’, a combination of French and Spanish powers whose interests had as much to do with containing the British as with freeing American colonists. So, with the fighting in America all but over, the biggest engagement of the war had yet to begin.

This gave George Eliott, the British Governor defending Gibraltar, something of a problem. He had been besieged by the Bourbon allies...