During the Napoleonic Wars, France conquered Egypt, Belgium, Holland, much of Italy, Austria, much of Germany, Poland and Spain. France directly conquered or controlled through alliance most of western Europe by 1812.
Driven by a desire to spread the French revolutionary principles throughout Europe, Napoleon first conquered Egypt to cripple British trade. He returned to France and, using both diplomacy and warfare, conquered neighboring states. Because much of Europe at the time was fragmented principalities and semi-autonomous states similar to modern Monaco or Luxembourg, it was simple to take over each country a bit at a time.
Although the French Empire ultimately failed, Napoleon changed the face of Europe, forcing the consolidation of Italy and Germany and crippling the power of the aristocracy.