The trope of "Napoleon the Conqueror" is as old as the British propaganda that was made to demean him. As a result of this, and as a result of Anglophone historiography that resulted from an Allied victory after Waterloo, Napoleon will always be an Ogre to many people rather than a complex human being that is far from the evil of his other comparisons, which I cover here in respect to the often used comparison to another actual conqueror of nations..

First and foremost, with two major exceptions, Napoleon never acted as an aggressor in the political realm of war. Every time that war was declared, it was one of the members of the Allies, the coalition of nations that had joined in the fight against Revolutionary and Napoleonic France for the purpose of ending Revolutionary or Napoleonic rule. The principal players were Great Britain (funding the various members with loans or gold, fighting from 1793-01, 1805-14, and 1815), Prussia (fighting from 1793-5, 1806-7, 1813-14, and 1815), Austria (fighting from 1793-1802, 1805-6, 1809, 1813-14), Russia, (1798-9, 1805-1807, 1812-14, 1815), and Spain (fighting from 1808-1814) in a series of six coalition wars (all variously smaller wars lumped together for the ease of historiography). There are multiple players and there is no way a singular person or nation could be to blame for the two decades of war, however France was on the defensive with two exceptions, yet Napoleon marched into enemy territory for the explicit purpose of making the enemy pay for the war by using resources from the local populace and keeping it away from France (protecting France's economic power and taxing the enemy's).

Now, the two exceptions of France's politically defensive yet strategically offensive campaigns are due to an economic policy aimed at the British. Britain, lacking many resources, resorted to a political policy aimed at protecting trade as income. To fight Britain's income, Napoleon aimed to create a virtual embargo of all trade between the European Continent and Great Britain in order to lock them out of Continental trade and starve them. However, it wouldn't work because Britain ends up diversifying trade through India and the Far East. This system would be the Continental System and enforced on Napoleon's enemies on the Continent. It would become important for Napoleon to strangle Britain of trade and this could only happen if every nation on the Continent; France imposed it on Prussia and Austria following their defeats, Russia would agree to it for peace, and Napoleon would invade Portugal through Spain and use a bad Spanish king to take Spain for his family (which would backfire through a combination of religious fervor, British funding, and poor leadership of French armies). This would become the Spanish Ulcer that would drain France of soldiers and officers.

The second aggressive political action in war that Napoleon would engage in is the French Invasion of Russia in 1812. By 1811, France & Russia would have a tense relationship after a series of minor slights (Alexander refusing a wife for Napoleon, disagreements and an end of a friendship between the two) and the movement of Russia to the British camp after promise of funds and a return to trade with Britain. The Russians were in the process of preparing for war by June of 1812 and had started trade with Great Britain, a clear break of the Continental System that Napoleon needed to enforce, and in enforcing it, Napoleon would invade Russia.

As for the land that France gained throughout the wars with Europe, that is something different. It is common to see maps such as this represent Napoleonic Europe. It is very misleading because most of that land may be allied with France directly or controlled by French governors. It is improper to argue that the Netherlands was "French" but rather it was governed by the Batavian Republic, which would become the Kingdom of Holland which was led by Louis Bonaparte, brother of Napoleon, but acted as an independent Kingdom (which would cause issues for Napoleon as Louis often acted in Dutch interests rather than French). Other places like Rome are nominally ruled by Napoleon while the North East of Spain and contemporary Croatia were ruled by military governors. What is interesting is that the Kingdom of Italy had Napoleon as the nominal head yet ruled by a viceroy, Eugene de Beauharnais (Napoleon's son-in-law from Josephine), whom was extremely effective both in combat (Napoleon wrote frequently to Eugene to give him advice on war, which is where many of his "maxims" come from) and as a leader (with the European allies even willing to grant him the throne of Italy, yet he refused out of loyalty to his father-in-law). Finally, the Confederation of the Rhine is actively protected by France yet counted as separate. (This map is a mess...)

However Napoleon did change the map of Europe. With the defeat of Prussia in 1807, Napoleon carved out the Grand Duchy of Warsaw, and claimed but never acted to restore the Kingdom of Poland. Lands would be taken from the enemy and given to allies or "liberated" by military governors. The Illyrian Provences are taken from the Austrians in 1806 and saw General August Marmont modernize the area and reportedly created the first stone roads since Rome. Other regions, like Tyrol (which belonged to Austria and still is a part of it) was given to the Kingdom of Westphalia in 1806 as a reward for being allied with France and receiving the first acts of the Austrian invasion which prompted the War of the Third Coalition (Austrian theatre). This was common in the 18th century, lands would shift between monarchs like puzzle pieces while leaving the locals generally uninvolved in the status of their "nationality" and would end with the Napoleonic Era with some exceptions (the loss of Alsace-Lorraine in 1870 is one of the more significant exceptions).

Napoleon conquered Europe out of necessity; in order to defend France from countless wars waged against her (at first out of fear of a change in the establishment, then anger in how Napoleon treated the defeated), with two exceptions. Lands passed between nations as war trophies and tokens of thanks, areas modernized through necessity despite being French for weeks or months. Whether it is right or not that Napoleon did so, he did it with gusto and near malice. Anger was had for enemies that rose against France and looked to destroy his Empire (particular anger toward Great Britain, which he called a "Nation of Shopkeepers"), thus punishments were doled out with territory changes. Napoleon defeated his enemies, but conquered is not proper to say.