While he would have seen nothing like that, Napoleon was given a spectacular chess set for his own use during his exile on St Helena; it was, according to one account, a gift from "The Honourable John Elphinstone, a token of gratitude to Bonaparte for having saved the life of his brother, Captain Elphinstone, of the 15th Light Dragoons. He was severely wounded and made prisoner the day before the battle of Waterloo." The chess set, allegedly, was "Chinese . . . of exquisitely carved ivory, marked with eagles and the initial N surmounted by the Imperial Crown".

It would have been well used. In his Mémorial de Sainte-Hélène, Napoleon's companion in captivity, le Comte de Las Cases, wrote that "before dinner the emperor always played several games of chess". The question to which we would all like the answer is, of course: how good a player was Napoleon? His successful military campaigns were characterised by a style that we associate with the greatest chess players: speed of attack, combined with an ability to concentrate force with maximum impact on the opponent's weakest point. Yet although a spectacular game allegedly played on St Helena against his aide-de-camp General Bertrand shows some of that brilliance, it is nowadays regarded as a hoax: a game between two genuinely strong players of the day and attributed to Napoleon for literary purposes.

In 1836 an issue of La Palamède (the world's first chess magazine) contained an account of Napoleon's chess skills by the Duke of Bassano, who had actually played the great military leader on a number of occasions. He wrote: "The Emperor was not skilful in opening a game of chess. From the outset he often lost pieces and pawns. It was only in the middle game that he was inspired; the mêlée of pieces kindled his intelligence."

Obviously, there is no reason why a brilliant military strategist should be anything more than a mediocre chess player, even if it was his favourite pursuit away from the battlefield. The construction of a real-life battle plan, while resting heavily on deception, does not require anything like the powers of geometric visualisation essential in calculating long chessboard variations. In some respects warfare is closer to a game like poker, in which it is impossible for much of the time to know exactly what the opponent has at his disposal — chess is an "open information" game, by contrast.

That Napoleon could even have been a poor chess player is given greatest credibility by the game which he is said to have played at the Schönbrunn Palace in 1809 against the Mechanical Turk. This was a fake chess-playing machine which was one of the sensations of Europe from the late 18th century until its destruction by fire in 1854. The "machine" in fact contained an artfully concealed operator, who at the time Napoleon played "it" was the German chess theorist Johann Allgaier.