I'm not really an historian, french revolution is not my favourite period but as a french i think i still have some knowledge to talk about it.

French revolution escalated quickly, at the origins nobody wanted to overthrow the monarchy. (If you don't already know the white in the french flags is the sign of the royalty.) People just wanted change, but would still follow the king. Even after the takeover of the Bastille (Royal jail), the king was still the king and the huge majority of the french didn't want that to change.

But like always, things got worse, the king wouldn't accept every change asked by the population, and tought he will not last long at this rate, and decided to get back the country by force with the help of other countries. He left versaille and tried to escape to austria where he would be safe and would be able to launch the attack from there, but that settled his fate.

The reign of terror come from that, trust was broken between the revolutionary and the king, between the nobles and the king, between the revolutionary and the noble, even amongst the revolutionnary so far working together, some conflict started to appeared.

It's not different from what happened nowadays, as soon as your common enemy is no longer, you don't think about what you have in common, but what difference you have. Not all the revolutionary had the same idea, some of them still tought the noble were needed, and didn't want a mass murder. The other part, were strongly against all the noble, and were thinking the noble were all traitor and the other revolutionaries their ally.

When you don't have any common goal, no plans for the future, different opinions about what you want, no common ennemy and nobody on top of everything to settle it. It's predictable that nothing good will happen.

The republic was still new, and not strongly established, some people were still against it, the noble and their followers for example, but also the church who has lost a lot during the revolution. With strong opponent, from both the inside and the outside, the republic was in bad shape, and they used the strong way trying to consolidate it. Every person that had a different opinion, was a traitor, or will soon or later be an enemy of the republic.

It's hard to summarize the whole thing even more in english , but this is how i see what happened at that time, now for what i think about it, here we go.

The reign of terror, is not the best moment in the french history, but it was inevitable. You need to take in consideration the world situation at that time. France was a strong kingdom, and despite fighting with almost every other countries in europe, that was the first time, they were the enemy of everyone at the same time. All the other kingdom dreamed of conquering the country and put his cousin or anyone else in top of the new monarchy of the kingdom.

People feared that the french noble would follow the king step and betray their country an join an other kingdom. They needed a strong governement able to settle everyone under it, but they choose to do it by the terror, and thing got out of control. When almost anyone feared to be called a traitor and be executed, they started to go against the executioner, even if they had globally the same opinion.

That's some years of terror, but something needed to be done, they choose one way to do it, i'm not really a fan of it, but at least they did it, and the country learned something.

Ps : Sorry for my english, you may (will) find some mistakes, i'm sorry about it. If you have any precise question about it i would be glad to anwser it, it's hard to talk about something so large.