The Jacobin revolutionary who led the Reign of Terror was Maximilien Robespierre. Initially, Robespierre opposed using the death penalty, but counter-revolutionary uprisings caused him to implement executions as a means of advancing the French Revolution.
Maximilien Robespierre began life in Arras, but attended grammar school in Paris. Although he came from a bourgeois background, he took a radical stance when it came to the rights of France's citizens. While some individuals supporting the French Revolution did not believe in giving rights to those who did not own land, Robespierre did. As such, he was considered a far-left member of the movement.
Robespierre first became involved in the revolutionary movement while in his early thirties. Although he attempted to establish a constitutional monarchy with his contemporaries, France's political and economical state declined severely between 1789 and 1792. When the revolution failed to benefit the population in general, there were uprisings calling for an absolute end to the monarchy. From 1792 to 1793, France became involved in wars abroad, and there were counter-revolutionary movements within the country. When France's population became restless due to lack of progress, they supported using the Jacobins to lead the revolution instead. Robespierre changed his stance on the death penalty and began supporting the executions the country seemed to be calling for.
Between June 1793 and September 1794, more than 16,000 people faced execution in the form of the guillotine and mass beatings. The Reign of Terror came to an end when Robespierre himself was executed.