The name of Maximilien Robespierre has come to be associated with the most violent phase of the French Revolution, The Reign of Terror. It is this particular phase that tends to epitomize the French Revolution for most people: that terrible period in European history when violence and bloodshed were the order of the day and countless innocent victims were dispatched by the swift blow of the guillotine.
Robespierre, like most political fanatics, genuinely believed that what he was doing was right. He regarded himself as the paragon of revolutionary virtue, an incorruptible man of integrity whose determination to defend the Revolution at all costs was second to none. Robespierre looked about him and saw only traitors and backsliders, who lacked his firm, unshakeable conviction. He developed a paranoid mindset which encouraged him to believe that the Revolution was under threat from all sides and that only he could save the nation from traitors both within and without.
To do this, Robespierre insisted on the necessity of terror. As head of the notorious Committee of Public Safety, Robespierre became the most powerful—and feared—man in the whole of France. He used his immense power to root out and destroy anyone he thought might be a threat to the Revolution, using the most ruthless methods available. Violence and bloodshed had always been part and parcel of the Revolution from day one, but under The Terror it became a regular feature of public life.
So long as France was besieged by hostile foreign powers who wanted to restore the French monarchy, then terror could in some ways be justified as a necessary measure to protect the nation from traitors and saboteurs. But once the tide began to turn in favor of the French Revolutionary Army, which chalked up a remarkable string of victories on the battlefield, then it became much harder for Robespierre and the other radical Jacobins to justify their increasingly repressive policies.
Inevitably, Robespierre, intoxicated with power, overreached himself. By threatening to extend The Terror, he frightened many of those politicians who'd previously kept their heads down to side with his most bitter enemies. The ensuing coalition made its move, and Robespierre, along with many of his comrades, ended up suffering the same fate to which he'd consigned thousands of innocent people: death by guillotine.