Reign of Terror refers to a period during the French Revolution after the First French Republic was established and it lasted from September 1793 until the fall of Robespierre in 1794. Its purpose was to purge France of enemies of the Revolution and protect the country from foreign invaders.
The key reason for Calvin Coolidge's victory in the 1924 presidential election is that they managed to get voters from southern states to vote for him! Hope this helps!