Few men have dominated an age so thoroughly as Napoleon Bonaparte dominated his. In many ways he was like Adolph Hitler: charismatic, a master psychologist and politician, and ambitious to the point of self-destruction. Both started wars that led to vast destruction and a new political order. Both men shaped their times, but both were also products of their times who went with the currents of their respective histories and adeptly diverted those currents to suit their own needs. And ultimately, both were dismal failures.
To a large extent, Napoleon's career resulted from the military and political forces he inherited from the Revolution and exploited for his own purposes. In military affairs, he was lucky to inherit the military innovations of the French Revolution, such as mass conscription which made possible the use of block tactics in order to attack in column and eliminated the need for supply lines, thus making French armies much more mobile. Therefore, the two characteristics of Napoleonic warfare, massed firepower and mobility were already present when he started his career. However, it was Napoleon's genius that knew how to use them effectively in his first Italian campaign against the Austrians.
Politically, France had suffered a full decade of revolutionary turmoil by 1799, making the government unstable and corrupt. Church policies were unpopular, especially since they had triggered rampant inflation. People were sick of this turmoil and longed for a more stable government that would make their lives more secure. Therefore, the interplay of military innovations that made Napoleon a national hero and the longing for a strong, secure government that Napoleon promised led to his seizure of power in 1799. Further military victories, once again against the Austrians in Italy allowed Napoleon to consolidate his hold on power and declare himself emperor of France in 1804.
While we mainly think of Napoleon as a general, he was also a very active administrator, and his internal reforms did a great deal as far as both consolidating some accomplishments of the French Revolution and suppressing others. One way to assess his government of France is to see how it conformed to the revolutionary motto: "Liberty, fraternity (i.e., nationalism), and equality". As far as political and civil liberties were concerned, Napoleon largely suppressed them with strict censorship and the establishment of a virtual police state in order to protect his power.
However, Napoleon saw equality as a politically useful concept that he could maintain with little threat to his position. After all, everyone, at least all men, were equally under his power. One of his main accomplishments as a ruler was the establishment of the Napoleonic Civil Law Codes, which made all men equal under the law while maintaining their legal power over women. Therefore, any hopes women may have had of the Revolution improving their legal position were thwarted by Napoleon.
Napoleon saw nationalism as indispensable to maintaining the loyalty of the French people to his regime. After all, it was the spirit of nationalism that had inspired its armies in a remarkable series of victories that had especially benefited Napoleon and allowed his rise to power. The trick was for Napoleon to build a personality cult around himself so that the French people would identify him with France itself and therefore make loyalty to him equivalent to loyalty to France. However, by identifying national loyalty with one man, Napoleon inadvertently weakened the inspirational force of nationalism and thus his own power.
Overall, Napoleon's internal policies strengthened France and allowed it to dominate most of Europe after a series of successful military campaigns (1805-7). Naturally, he established his style of rule in the countries he overran. However, he mistakenly thought that the administrative and legal reforms of the revolution he carried to the rest of Europe could be separated from the ideas of Nationalism and Liberalism (liberty and equality) that had given those reforms life and substance. Therefore, Napoleon's imperial rule inadvertently spread these ideas of Nationalism and Liberalism.
This had three effects, all of which combined to overthrow Napoleon. First of all, the empire's non-French subjects picked up the ideas of Nationalism and Liberalism and used them to overthrow, not support, French rule. Second, subject rulers adopted many of the very military and administrative reforms that had made France so strong. Once again, this was not to support French rule, but rather to overthrow it.
Finally, Napoleon's power and success up until 1808 apparently blinded him to his own limitations. Therefore, he got involved in a long drawn out war in Spain (1808-14) and launched a disastrous invasion of Russia (1812). This led to the formation of a new coalition that finally defeated and overthrew him in 1815. The victors met at the Congress of Vienna, hoping to restore the old order as it had existed before the Revolution.
However, despite his intentions, Napoleon had effectively planted the seeds of Nationalism and Liberalism across Europe, and these ideas would spread in new waves of revolution by mid-century. Europeans would take these ideas, along with the powerful new technologies unleashed by the Industrial Revolution, to establish colonies across the globe by 1900. Ironically, these European powers, like Napoleon, would fall victim to the force of these ideas when their subjects would use them in their own wars of liberation after World War II.