The Spanish Parallel
The simultaneous disasters in Spain and Russia revealed the fundamental overstretch of French resources. Napoleon's attempt to control both ends of Europe exceeded French capabilities while providing enemies with opportunities to exploit French weakness. The guerrilla warfare that had begun in Spain spread to Russia, where Cossacks and peasants harassed French communications just as Spanish guerrillas had done.
Wellington's victories in Spain during 1812-1813 demonstrated that French forces could be defeated even when not distracted by Russian disasters. The Battle of Salamanca in July 1812 was a tactical masterpiece that destroyed French power in central Spain, while the siege of Burgos showed that French defensive positions could be reduced by patient siege warfare.
The Spanish war's human cost was staggering. Over six years of fighting, French casualties in Spain exceeded 300,000 men, while Spanish losses were proportionally even higher. Entire regions were depopulated, cities destroyed, and the Spanish economy ruined. The war's brutality, captured in Goya's "Disasters of War" etchings, revealed the true cost of Napoleonic ambition.