There could have been an innocent explanation for the dust cloud: it could have been caused by a herd of cows being driven to market, by a Prussian regiment on exercise, or even by a work gang hammering cobbles into the highway’s bed of chalk and flint, yet the musket-fire Sharpe had heard earlier, and the presence of the enemy Dragoons on the southern bank of the Sambre suggested a more sinister cause.

Invasion? For days now there had been no news from France, evidence that the Emperor had forbidden all traffic over the border, but that silence did not necessarily suggest an immediate invasion, but rather the concealment of exactly where the French forces concentrated. The best allied intelligence insisted that the French would not be ready till July, and that their attack would advance through Mons, not Charleroi. The Mons road offered the shortest route to Brussels, and if Brussels fell the Emperor would have succeeded in driving the British back to the North Sea and the Prussians back across the Rhine. Brussels, to the French, spelt victory.

Sharpe urged his horse down the rutted lane that dropped into a shallow valley before climbing between two unhedged pastures. He veered to his right, not wanting to betray his presence with dust from the dry mud of the lane. The mare was breathing hard as she trotted up the pastureland. She was accustomed to exercise for, each morning for the past two weeks, Sharpe had saddled her at three o’clock, then ridden her south to watch the dawn break over the Sambre valley, but this morning, hearing the crackle of musketry to the east, he had ridden the mare much further than usual. The day also threatened to be the hottest of the summer, but Sharpe’s fears of the enemy’s mysterious appearance made him force the beast onwards.

If this was the French invasion then the news of it must reach the allied headquarters quickly. The British, Dutch and Prussian armies guarded eighty miles of vulnerable Dutch frontier; the Prussians to the east and the British and Dutch to the west.