July 14th celebrates the day the Bastille in Paris was stormed, thus leading to a major turning point in the French Revolution. Shortly after, feudalism was abolished.
Bastille day represents something much bigger than the sovereignty of the people, when one looks deeper, though people often want to leave it at that. Reactionaries often point to the French Revolution as the beginning of modernity, with which they give themselves no option but to have an antogonistic relationship, and many of them would prefer some type of monarchy.
Bastille day represents the moment in history when the Divine Right of Kings died in a metaphysical sense. That's something most reactionaries are not willing to admit. Monarchy was dead long before it was actually abolished (or in some countries, made impotent). Sovereignty was always a two-way relationship. When Royalty failed to do what it needed to keep the demos happy, the demos took over.
Bastille day is a good reminder that power is not about what one possesses, but that it is always a relationship. For whatever good or bad came out of the French Revolution, it was an inevitability born out of the impotence of an old power system that no longer believed in itself enough to continue into the next era.