The Russian Campaign began as a result of Tsar Alexander 1st disreagard for the embargo that Napoleon had boycotting the trade on Britsh goods. Napoleon decided the Russians needed to be brought back into line and so amassed a contingent of more than 500,000 troops in Poland including Prussian and Austrians as a warning of invasion to Russia.
Tsar Alexander chose to ignore Bonaparte's threats and ordered two Russian armies to protect the motherland. on the 24th June, 1812, Bonaprte crossed the river Niemen on advance to Moscow and so began the loss and killing of over 500,000 men.
The weather and shortage of supplies contributed to Napoleon's defeat and by the time that Bonaprte entered Moscow his already depleated by battles, illness and heat exhaustion. Napoleon entered a Moscow, that was already burning and set alight by the Russians themselfs. After staying to long in Moscow, Napoleon against the sound advice from his Marshal's began a long reatret back thruogh territory he and his men already plundered. This decsion alongside Cossack attacks, abd weather and hunger resulted in the failure of Napoleon's great Russian Campaign.
Marshal Michel Ney defending the rearguard of the retreating Grand army of Napoleon but in was the two day battle at Berezina, that 32'000 died crossing a bridge that collapsed and the Russians army had the advantage of shelling the Grand Army from postions overlooking the river.
On the 7th December 1812, only 20'000 french soldiers survived, finally Russian soil.
What began with more that 500'000 troops, ended in a bitter tragady.