LOS ANGELES, CA (Catholic Online) - "My cavalry is in tatters, many horses are dying," Napoleon says in his pleading missive. It's a sterling example of how far the mighty can fall, penned at a time when his calamitous Russian invasion halved his army.

Dated Oct 20, 1812, signed "Nap" in the emperor's hand and written in numeric code is up for auction this weekend at France's Fontainebleau Auction House.

Used only for top-secret letters when the French emperor was far from home, the Napoleonic code attempted to halt enemies from intercepting French army orders. The code was regularly changed to prevent it from being cracked.

The system presumably used Napoleon's strongest horses and riders to carry the news: It only took three days to reach France's interior ministry - 1,540 miles across Europe.

"This letter is unique. Not only is it all in code, but it's the first time we see this different Napoleon. He went into Moscow in 1812 at the height of his power. He returned profoundly weakened. In Moscow, the Russians had fled days before and burnt down the city. There was no victory for Napoleon, nor were there any provisions for his starving, dying army," Jean-Christophe Chataignier of the auction house says.

Napoleon final order was to burn Russia's government buildings - coded in the letter as "449, 514, 451, 1365..."

Historians cite the letter as evidence of the general's fall, wherein Napoleon's "glorious empire," which started in Russia and ended in disgrace at Waterloo three years later.

In June 1812, Napoleon's "Grand Army," at 600,000 men one of the largest in human history entered Russia. Unprepared for the harsh weather, the strong Russian defense and its scorched-earth tactics, nothing was left behind to sustain the hungry and freezing French troops.

"This letter is an incredible insight, we never see Napoleon emotively speaking in this way before," Chataignier says. "Only in letters to (his wife) Josephine did he ever express anything near to emotion. Moscow knocked him."

The message announces that his commanders are evacuating Moscow and Napoleon laments his army's plight, asking for assistance to replenish his forces and the ravaged cavalry, which saw thousands of horses die.

The letter, which is accompanied by a second decoded sheet, is estimated to fetch up to 15,000 euros.

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