Well in Russia he lost a majority of his army due to the cold winter which cut off supply lines and caused a lot of soldiers to die. In addition the Russians basically didn't leave any food behind and destroyed the land so that Napoleon's soldiers couldn't live of the land.
**Napoleon Bonaparte **made costly errors in both Spain and Russia. His imposition of his brother as Spanish royalty led to an uprising and protracted, expensive warfare, while his failed invasion of Russia led to massive loss of life and his eventual abdication. His Continental Blockade policy also resulted in strife and burden for the Spanish citizens. ;
Napoleon made significant mistakes in both Spain and Russia. In Spain, his decision to install his brother as king led to the Peninsular War, severely draining resources and manpower. In Russia, his invasion was plagued by logistical failures, harsh winter conditions, and the scorched earth tactics of the Russians, resulting in massive losses for his army.
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