No one, conveniently for a writer of fiction, knows the precise cause of the catastrophe, but the accepted version, pieced together from the stories of survivors, is that a leaking keg of gunpowder was rolled from the cathedral and an exploding French shell ignited the accidental powder train, which fired back to musket ammunition stored by the main door. This, in turn, flashed down to the main magazine, and so the greatest obstacle between Massena and his invasion of Portugal was gone. One Portuguese soldier, very close to the cathedral, saved his life by diving into a bread oven, and now his presence of mind has been borrowed by Richard Sharpe. The most unlikely stories often turn out to be the truth.

The Lines of Torres Vedras existed and truly were one of the great military achievements of all time. They can still be seen, decrepit for the most part, grassed over, but with a little imagination Massena's shock can be realized. He had pursued the British army from the border to within a day's march of Lisbon, had survived Wellington's crushing victory at Busaco on the way, but surely, so close to Portugal's capital, he must have thought his job done. Then he saw the lines. They were the furthest point of retreat for the British in the Peninsula; they were never to be used again, and four years later Wellington's superb army marched over the Pyrenees into France itself.

Sharpe’s Gold is, sadly, unfair to the Spanish. Some Partisans were as self-seeking as El Catolico, but the large majority were brave men who tied up more French troops than did Wellington's army. The Richard Sharpe books are the chronicles of British soldiers and, with that perspective, the men who fought the 'little war' have suffered an unfair distortion. But at least, by the autumn of 1810, the British army is safe behind its gigantic Lines and the stage is set for the next four years: the advance into Spain, the victories, and the ultimate conquest of France itself.

Richard Sharpe and Patrick Harper will march again.