The French Revolution ran for a decade (1789-99) and saw fundamental changes in French society as a result. The monarchy came to an end as did the entire feudal system that had run France for centuries. It began with the assault on the much-hated Bastille where the king's enemies had been imprisoned, and then a march to Versailles.
For several years the monarchy and the revolutionaries faced off without either side having momentum. Then in September 1792 the Republic was formally proclaimed liberated by "liberal" forces. King Louis XVI was beheaded the following year. The death of the king paralleled the rise of Maximilien Robespierre and the year-long Reign of Terror where up to 40,000 people faced the guillotine for a variety of reasons, many insubstantial. Robespierre was finally murdered by guillotine and after a few more years of turmoil, Napoleon Bonaparte came to power and the era of France's expansion and its Napoleonic Wars had begun.
The French Revolution, which led to the rise of Napoleon, shows us how violent revolutions can go wrong. Born of the Age of Enlightenment, which gave way to the Age of Reason, the Revolution soon emphasized the "reason" of human beings over any other influence. Reason eventually gave way to the martial despotism of Napoleon. While the American Revolution based its premise of natural law on God-given rights, the French Revolution placed the reasoning man at the heart of the state. This led to disastrous consequences once Napoleon assumed the mantle of "the man with the most reason."
If human beings, through the exercise of reason, can create perfected states then the state itself is the source and fountain of power. Whether it is the French Revolution, the Russian Revolution or the Chinese Revolution we can see how this misguided perception has eventually led to the deaths of millions. In France, the perfectibility of mankind led to the rise of Napoleon and eventually to serial warring. In Russia and China, under communism, the theory that human beings through reason could build utopian worlds led eventually to massive starvation and genocide.
There is no way to build better societies but patiently by way of education and reasoned discourse, acknowledging as one does so that human beings are fallible creatures and that there is no divinity on Earth that can create a perfect society for all. The more one tries, the less one succeeds. Societies are best run in the smallest increments possible and by respecting natural law and the ability of humans to create their own prosperity through the exercise of human action benefitting themselves, their families and the larger local community.
The French Revolution, for all its promise, provides us with an example of what happens when violent revolutions are accompanied by a faith in the perfectibility of the human beings who are making the revolution. It is very important that revolutions do not feature violence and create the conditions for gradual evolution of fairer social conditions emphasizing free markets and the primacy of individual human action. These are the keys, not grand schemes that lead inevitability to the primacy of the state.