The French Revolution was successful at defending the Revolution from its enemies inside and outside of France. But failed horrible by the way they were keeping things under control. The French citizens were controlled by fear and nothing else.
There were many reasons why the French Revolution came into play. For example, many were inspired by the outcome of the American Revolution, so many thought they had a chance and could do the same. And another big reason is because France was deeply in debt, so they tried many schemes invoking taxes.
The reign of terror was a time during the French Revolution when multiple members of radical groups came into power, and used fear to control the people. One way of doing this was by either arresting or executing those who made even the smallest of crimes. This reign lasted for 10 months and around 300,000 people and arrested and about 17,000 people were sentenced to death by guitine, including the king, and one of the most radical leaders; Maximillen Robespierre.
Many citizens in the French society did not question the government during these 10 months in fear of being executed or arrested. By orders of the radical leaders, they were to eliminate any resistance to the Revolution. This is what set the reign of terror into action.
Many countries, including Britain found the French Revolution to be disgusting and cruel. For example, a British news paper used words like "diabolical" and "savag" to show their disgust of this event. Most Americans thought something similar but blamed it on the French government its self. Thomas Paine said that the Goverment was already corrupt, and that they should have taken out the corrupter ones with powers sooner.