Photo: The Canadian Press. All rights reserved.

In this photo taken Wednesday, Nov. 28, 2012, a letter dictated by Napoleon in secret code that declares his intentions "to blow up the Kremlin" during his ill-fated Russian campaign is displayed in Fontainebleau, outside Paris. The rare letter, written in unusually emotive language, sees Napoleon complain of harsh conditions and the shortcomings of his grand army. The letter goes on auction Sunday, Dec. 2, 2012. (AP Photo/Christophe Ena)

A secret code letter sent in 1812 by Napoleon Bonaparte boasting that his French forces would blow up Moscow's Kremlin has sold at auction for ten times its estimated presale price.

A Paris museum -- the Museum of Letters and Manuscripts -- was finalizing its purchase of the Oct. 20, 1812, document for $243,500, including fees. That's far above the pre-sale estimate of $19,500.

Auctioneers at Fontainebleau Auction House south of Paris say the letter sold Sunday is unique. It was written in a numeric code used by the French ruler to throw off would-be interceptors. Its content bared the strains on Napoleon of his calamitous Russian invasion.

One line said: "At three o'clock in the morning, on the 22nd I am going to blow up the Kremlin."