Napoleon had invaded Russia in 1812 to…

Napoleon had invaded Russia in 1812 to compel Emperor Alexander I to remain in the Continental System.

The Grande Armée, consisting of as many as six hundred and fifty thousand men (roughly half of whom were French, with the remainder coming from allies or subject areas), had crossed the Neman River on June 23, 1812.

Russia had proclaimed a Patriotic War, while Napoleon had proclaimed a "Second Polish War", but against the expectations of the Poles, who had supplied almost one hundred thousand troops for the invasion force, and having in mind further negotiations with Russia, he had avoided any concessions toward Poland.

Russian forces had fallen back, destroying everything potentially of use to the invaders until giving battle on September 7 at Borodino, where the two armies fought a devastating battle.

Despite the fact that France had won a tactical victory, the battle was inconclusive.

Following the battle the Russians had withdrawn, thus opening the road to Moscow.

By September 14, the French had occupied Moscow but found the city practically empty.

Alexander I (despite having almost lost the war by Western European standards) had refused to capitulate, leaving the French in the abandoned city of Moscow with little food or shelter (large parts of Moscow had burned down) and winter approaching.

In these circumstances, and with no clear path to victory, Napoleon had been forced to withdraw from Moscow.

So began the disastrous Great Retreat, during which the retreating army came under increasing pressure due to lack of food, desertions, and increasingly harsh winter weather, all while under continual attack by the Russian army led by Commander-in-Chief Mikhail Kutuzov, and other militias.

Total losses of the Grand Army were at least three hundred and seventy thousand casualties as a result of fighting, starvation and the freezing weather conditions, and two hundred thousand captured.

By November, only twenty-seven thousand fit soldiers had re-crossed the Berezina River.

Napoleon had then left his army to return to Paris and prepare a defense of Poland against the advancing Russians.

The situation is not as dire as it might at first have seemed; the Russians have also lost around four hundred thousand men and their army is similarly depleted.

However, they have the advantage of shorter supply lines and are able to replenish their armies with greater speed than the French, especially because Napoleon's losses of cavalry and wagons are irreplaceable.