July 1812 - undeclared French invasion.
Russian slow retreat in conditions of number inferiority.
August 1812: Smolensk battle .
September 1812: Borodino clash (the initial forces and the resulted losses
in that general battle of the war were almost equal)
; fire of Moscow.
October-december 1812: French retreat from Russia, forsed by the regular troops and partisans.
At the border, only 1600 Frenches left of The Great Army (about 3%).
The broken cannons at Borodino field (click to enlarge).