Why did the French Revolution slip back from its original enlightened ideas and move towards authoritarian regimes.

The French Revolution began with enlightened ideas of liberty, equality and fraternity but ended up with authoritarian regime. We see after the king Louis XIV, the revolutionary factions like Goirondons, Cordliers, Montgnards and Jacobins become more radical and dogmatic as the revolution progressed. Thousands of people were killed and persecuted (Reign of Terror 1794) by these so called republic revolutionary radicals. They began to work for their private agendas rather than for public good. Later we see Napoleon became the dictator of France and fallowed an expansionist policy. So the revolution in true sense was a transition from one authoritarian regime to another.