During Napoleon’s invasion of Russia in 1812, the French emperor came to the realization that he would have to abandon Moscow and order the retreat of his Grand Armée. In a coded letter to his foreign minister, he announced that he was planning to plant bombs in the Kremlin to destroy its fortifications before beginning the retreat.

This letter was sold at auction this week and purchased by the Musée des Lettres et Manuscrits in Paris.

The BBC reports on the auction.