WARNING: I am not a historian, and barely know what I’m talking about. I’d love for someone to do some fact checking for me.
In the 1780s France was well out of the Middle Ages, but there were many, many aspects of society that retained the “irrational” history of feudalism. For example, laws legitimized distinctions between three different levels of citizenship: the aristocracy, the Church, and everybody else (a.k.a. “the people”). The king’s budget crisis got the ball of the revolution rolling when he put the responsibility of resolving the problem on a legislative body of representatives from each of these three equal-vote groups, which is to say, the very small constituencies of the first two groups had equal voice at the table as all of the rest of France. The ideas of the Enlightenment were in full swing by this point, and the French had recently helped the American’s in their revolution against the king of England.
While they may have intended to solve the budget problem, the “Third Estate” (the people) quickly got distracted by the idea of getting everybody to work as one legislative body on the budget, rather than three separated groups who would each have an equal voice. The aristocracy and Church preferred to work within their own groups, and then come together afterwards (as originally planned). A few priests joined the Third Estate, and after one month the Third Estate decide to call themselves the official legislative body of all of France, and called themselves the National Convention, refusing to recognize the legitimacy of the first two “estates.” This was the first step in forming the Republic, though they still left some authority for the king. They wrote a constitution capturing their Enlightenment values. It should be noted that no one wanted to get rid of the king yet. It should also be noted that the representatives of the Third Estate were educated doctors and lawyers that voted accordingly. Finally, it is worth mentioning that there were Enlightenment thinkers among the aristocracy and clergy, as well.
The political unrest in the National Convention contributed to a major symbolic outburst, when the people “stormed the Bastille,” a castle-turned-prison populated by a few of the monarchy’s political prisoners. It was a very symbolic moment. The people carried around a few guards’ heads on sticks to celebrate their victory.
During this time the Left and the Right wrestled vigorously. We get these terms, the Left and the Right, from the French Revolution, because it was a literal description of the seating of those in the National Convention, now called the Legislative Assembly, or something. I lose track. The Right included those who wanted to give the king quite a bit of power, while the Left wanted the king to remain a figure head. The center Left were liberals who believed in reason, war, freedom of the press (kinda), free trade, property, and the rule of law. The far Left, including Robespierre, opposed war, opposed capital punishment, opposed freedom of the press when the press was counter-revolutionary, opposed free trade when it harmed the poor, supported full (male) emancipation, and supported the political outbursts of the people (a.k.a. “the mob”).
Progressively the king became more unpopular. Eventually he decided to escape the country, which failed, and resulted in things getting a lot worse for him. Now there was no question- he proved himself to be a traitor and an enemy of the people.
The patriotism of the new Republic was strong, and most people felt like going to war with the Austrians (and a few other countries) was a good way to prove how great they were. The king supported it because he thought it would result in Austria setting him free. He was wrong.
On August 10 the French de-kinged the king, who then became “citizen Louis.” Shortly afterwards they put him on trial, making up the legal justification as they went, because this had never happened before, and eventually guillotined him (how very humane).
There were more public outbursts of violence, which Robespierre defended as a necessary part of the very revolutionary spirit that had set the people free in the first place. By this point the entire Legislative Assembly (which may or may not have changed its name again) was entirely Leftist, due to the new laws that gave all men the right to vote. The “people” (of Paris) wanted nothing to do with no-good “unAmerican” (or should I say “unFrench,” uneaters of “Freedom Fries!”) conservatives.
The far Left fought for price controls on a number of foods in order to address food shortages and cost hikes. The price controls were popular, but failed to actually address the food shortages and what appeared to be price gouging. The belief was that the wealthy were hiding food, inflating the costs, but this conspiracy theory appears to have been false.
From the beginning, and getting increasingly worse, was the fear of undercover counter-revolutionaries. The Left proposed that anyone who caused disunity should be executed, an idea accepted by the center Left and far Left. This crackdown was targeted at the wealthy and powerful conservatives, but also some peasants. As the peasants in the countryside that were growing frustrated with the oppression of the church from the revolutionaries, and the economic hardships caused by the revolutionaries’ Paris-mob-friendly laws, the far Left had to decide how they would respond to the outbursts of “the people,” which ended up being “brutally.”
Eventually the center Left were executed for actual and rumored ties to a counter-revolutionary coup, leaving the far Left alone to lead the Republic.
The far Left formed the Committee of Public Safety, in order to protect France from counter-revolutionaries. They initially observed rule of law as they put people on trial, but this fell away as hysteria increased. Robespierre eventually became the unofficial leader of the Committee of Public Safety, which consolidated power over the frequently renamed legislative body.
After some white collar crime resulted in cover ups within the legislative body, Robespierre argued that virtue was essential for government leaders, and Terror must be enforced on those who are corrupt. The government must treat itself harshly in order to rule the virtuous people.
Around the same time, as the war, the unrest in Paris, and the unrest in the countryside, were getting under control, the government essentially called a state of emergency. This was probably a response to the ever-increasing patriotism, hysteria and rumors. Some have speculated that Robespierre was experiencing a nervous breakdown by this point.
Robespierre led the arrest of a guy named Danton as a possible counter-revolutionary. You could say he was to Robespierre as Trotsky was to Lenin… and along those lines, I have heard Lenin admired and studied Danton as a revolutionary. This charge from Robespierre was absurd. Danton had been aligned with Robespierre from before it was popular to be far Left. This made everyone around Robespierre uncomfortable. Who would he execute next? (FYI: There is a Criterion movie about the last days of Danton.)
The Committee for Public Safety escalated executions, guillotining thousands of people, disproportionately from the countryside (the aristocracy escaped France years ago); people who were probably turned in by their neighbors due to private grievances, not conspiracy. This period was called “the (Great) Terror.” It happened quickly and efficiently.
Shortly after Danton was killed, Robespierre was arrested and executed. After Robespierre’s death, checks and balances were put back in place in order to restore the Republic, though political unrest continued. The executions almost entirely stopped instantly, though the revolution continued for years, eventually leading to the conquest of Emperor Napoleon throughout Europe.