Before achieving its remarkable price, the letter went on display in Fontainebleau, south of Paris and, following the sale, looks set to be exhibited once more after being purchased by Paris' Museum of Letters and Manuscripts.

The letter was a rare display of Napoleon's desire to learn the English language following his defeat by the British at the battle of Waterloo. Dated March 1816, the letter was written to his aide and English teacher, the Comte de Las Cases, while Napoleon was imprisoned on the remote island of St Helena.

It starts: "It's two o'clock after midnight, I have enow sleep, I go then finish the night with you."

Despite his determination to understand his captors, Bonaparte's letter clearly demonstrates his struggle with the language of his enemy. For example, the French emperor addresses Las Cases "at his bonk", when he supposedly meant "bunk".

"It's very moving, since it's one of the last pieces of writings in English before his death," commented 19th century manuscript expert Alain Nicholas, adding: "At the end he's written: 'Four o'clock in the morning,' so he wrote that in two hours. He took some time to write it. It shows he couldn't sleep and took his time. He had painful cancer in the stomach. He was an insomniac."

The letter's rarity and insight into the personality of the Little General was reflected at auction, where it shot past its pre-sale estimate of €60,000-80,000 to achieve an impressive €325,000 ($409,998).

Paul Fraser Collectibles has a superb collection of letters from Napoleon Bonaparte to buy without the need to go to auction. This letter, penned in 1812, was written to the Duc de Feltre, who would later become Napoleon's minister of war.

We are also offering collectors the chance to own an authentic strand of hair from history's greatest military leader.