A rare letter in English written by Napoleon Bonaparte – complete with errors − fetched €325,000 at an auction in Paris.

The one-page letter, dated March 9, 1816, penned by Napoleon during his post-Waterloo exile on the South Atlantic island of St Helena, was one of just three known in the world, said auction house Osenat.

Addressed to the Count of Las Cases, Napoleon’s companion in exile, the letter was acquired by the private Museum of Letters and Manuscripts in Paris and originally estimated to fetch just €60,000 to €80,000.

In his Memorial of St Helena, Las Cases wrote about how Napoleon began in March 1816 to correspond with him in English in order to practise the language of his jailers that he had began learning a few weeks earlier.

The count also wrote in particular about the auctioned letter, saying: “The emperor did not sleep that night − during his insomnia, he decided to write me a new letter in English.

“He sent it sealed to me, I corrected his errors and replied to him, in English also, by mail.”

Despite Las Cases encouraging words, Napoleon’s writing required some guesswork.

For instance, in one passage, he wrote: “He shall land above seven day a ship from Europe that we shall give account from anything who this shall have been even today of first January thousand eight hundred sixteen.”

Napoleon was referring to a ship from Europe that would dock in seven days, bringing news on what has happened since January 1, 1816.