Happy... what?
The French find the "patriotic" displays of Americans - the flags everywhere, the pugnacious slogans on bumper stickers - kind of apalling. Not really any kind of reassuring that we really appreciate our country. More like we're horribly insecure about it and ready to punch anyone who giggles.
We call the French national holiday Bastille Day, but it's just another way in which we don't get true patriotism. To the French, the storming of the Bastille is a very minor part of the whole story. Whereas, our national anthem is nothing but the story of just such a battle. We don't have much patriotism on display here, but we do have a poisonously intense strain of nationalism.
So in France you don't say, "Happy Bastille Day," but rather, "Bonne Fete Nationale!" Have a good national festival! Now go watch the fireworks across the Seine from the Eiffel Tower.