Was Borodino really a victory for Napoleon? Wasn't it more of a draw? Sure, the Russians retreated afterwards, so it didn't stop Napoleon's drive on Moscow. Still...
It was a Pyrrhic victory. At the end of battle, the Russian army retreated from the field and the French remained - so it was a victory by definition. But the French army could not replace its casualties or secure its supply lines, so the victory in battle resulted in defeat in the overall war.