In 1803, France was once again at war with Great Britain, and by 1805, Great Britain, Austria, Russia and Prussia had united to form the Third Coalition. Within two years Napoleon crushed the other European powers. With the defeat of the Third Coalition and the conclusion of the Treaty of Tilsit with Alexander I of Russia, Napoleon controlled most of Western and even Central Europe (from Spain to the Grand Duchy of Warsaw, with the exception of the Habsburg lands).

From 1807 to 1812 Napoleon was the master of Europe. His territorial ambitions and military genius had defeated continental Europe. The countries were either part of the enlarged French Empire, dependant states with Napoleon's relatives on the throne, or allied states (countries which had been defeated by him). The only enemy was Great Britain. 

Unable to defeat Britain at sea, he hoped to subdue the island nation with the Continental System, which cut Britain off from European trade. This hurt European nations too, though, and many did not strictly enforce the embargo. Russia finally refused to participate. The system failed to bring Britain to its knees.