Question: what was used by the revolutionaries to execute opponents
Answer: Several historians consider the `` reign of terror '' to have begun in 1793 , placing the starting date at either 5 September , June or March ( birth of the Revolutionary Tribunal ) , while some consider it to have begun in September 1792 ( September Massacres ) , or even July 1789 ( when the first beheadings by guillotine took place ) , but there is a consensus that it ended with the fall of Maximilien Robespierre in July 1794 .