His Russian ally was not agreeing with his Continental System, so he made the decision to invade Russia, a mistake. He led many of his troops, the Grande Armee, into Russia. However, the Russians had a tactic of schorched-earth-policy that they used, in which the Russians burned everything as they moved East, leaving nothing for the French. Napoleon captured Moscow, but it was also destroyed. The weather was an element that did not help. The winter Killed thousands of his army. He was defeated.