First of all, even before Napoleon Bonaparte, Napoleon was an unusual name, of Italian origin. So unlike, say, "Louis," there wasn't a longstanding tradition of naming kids "Napoleon" to be affected by the rise to power of the most famous Napoleon in history. (Contrast this, for example, with the precipitous decline starting anywhere from 1925 to 1945, depending on the country, in use of the once-popular name "Adolf" and its variants. We also, FWIW, see this in France with the name "Adolphe.")

The name Napoleon, in other words, is going to rise and fall based solely on Napoleon Bonaparte. And unfortunately for fans of the name Napoleon, during the height of the Napoleonic legend in the 19th Century, the name "Napoleon" was also an intensely political choice. During the periods when Bonapartes were not ruling France, members of the family were claiming the right to rule France — and, very frequently, exiled from the country for doing so, and often conspiring to bring this about. Naming your child "Napoleon" could be mildly (or not-so-mildly) seditious.

That's not to say that people didn't name their child Napoleon. Sudhir Hazareesingh's The Legend of Napoleon gives a number of examples of people in the period 1815-1848 who were named Napoleon, either as their full name or as part of the compound first names that the French loves so much. Many of those people ended up under police surveillance because of their seditious name, but Napoleon was popular enough (especially as he faded into legend) that people did it.

But here's the thing... Napoleon was a long time ago. Not one but two imperial Bonapartes were ignominiously kicked out of power in the 19th Century. The second, Napoleon's nephew Louis-Napoleon Bonaparte, a.k.a Emperor Napoleon III, was humiliatingly defeated and captured after provoking the ill-advised and disastrous Franco-Prussian War. That took a lot of the shine off the name "Napoleon."

Unfortunately I can't demonstrate that with certitude, because the digitized French baby name statistics only go back to the year 1900. But even by that point, just 30 years after the fall of the Second Empire, "Napoleon" was an almost completely unused name. It peaked with 24 baby Napoleons in 1902 and has gone down from there. There were no baby Napoleons between 1975 and 2008. In contrast, in 1902 there were more than 10,000 baby Louis.

Take a look at this chart I made of the post-1900 history of the name Napoleon.

To put this in even starker contrast, take a look at this chart showing the post-1900 history of the names of the five sons of Carlo Buonaparte: Joseph, Napoleon, Lucien, Louis and Jerome. All five names* were popular in the House of Bonaparte over the years. But among the common people, notice which one doesn't even register. It's Napoleon, the greatest by far of the Bonaparte brothers, but by far the least of their names.

*Note: This includes uses of these first names in compound or hyphenated names as well. The name Napoleon has not been used as part of a compound name in the available post-1900 database.