Why was russia’s defeat of france the turning point in the napoleonic wars?

Russia’s defeat of France was the turning point in the Napoleonic Wars because after that event Napoleon's empire turned against him.

Explanation:

In 1812 Russia opened its ports to British ships. Napoleon, who considered Britain as an enemy, sent the Grand Army - about 650,000 troops - against  the Russians to force them to recognize the blockade against the British and prevent their invasion of the Duchy of Warsaw, one of his closest allies.

On June 23, 1812 Napoleonic forces moved across the border through Russia, winning several minor clashes and the Battle of Smolensk on August 18, but on the same days the Russians stopped another part of French forces in the Battle of Polotsk, which protected them from marching to the then Russian capital of St. Petersburg. Nevertheless, the main French forces, led by Napoleon, continued their march to Moscow. The Russian army retreated using scorched earth tactics, destroying areas where Napoleon's forces had to march, and seeking to prevent the enemy from obtaining resources and food supplies. After the Battle of Borodin, Mikhail Kutuzov decided to leave Moscow without a fight. On September 14, the French army entered Moscow.

Napoleon had hoped that after the fall of Moscow, Alexander I would sign a peace treaty, but the latter disagreed and rejected all Napoleon's terms. Napoleon, fearing for a longer stay in Moscow, ordered the army to retreat. The situation was aggravated by early winter, and many French soldiers died of cold, hunger, disease. In addition, Russian attacks on the retreating French forces caused a huge amount of casualties. It was massacre, as only 100,000 of the 600,000 men that went to Russia survived.

The defeat caused amazement both in society and in the political sector of France, which began to see Napoleon as a tyrant who was not qualified for his position as general of the nation. Furthermore, in the face of the devastating defeat, Prussia and Austria decided to break their alliance with Napoleon, leaving him alone on the international plane.