This shouldn't be too surprising. Romanian is a romance language after all, in the same family as French. Even English has Latinate root words via the Norman invasion and the Catholic Church.
Romanian has close ties with France (Romanian children learn French at school, and I think until recently French was the foreign language most taught at schools) so some loanwords (like "merci") aren't unusual.
Good luck with the language! :)
So I found France's Foreign Diplomacy website, and their page on Romania. Here's an excerpt:
"The spread of the French language in Romania dates back to the 18ᵗʰ century, when the Romanian principalities of Wallachia and Moldova were still under Ottoman rule and the sons of the great Romanian families left to study in Paris. [...] Political relations between France and Romania date back to the role played by Napoleon III in the creation of the Romanian State on the European stage in the 19ᵗʰ century, then France’s assistance (in competition with Germany, however) for the establishment of this new State. "
You're right that a Napoleon played a part, but you were probably thinking of the wrong one ;)
Here's the original page if you're curious: http://www.diplomatie.gouv.fr/en/country-files/romania/france-and-romania/