From its first performance on April 14, 1713 Joseph Addison’s play Cato: A Tragedy captured the imaginations of theatregoers in Britain and North America with its themes of liberty and resistance to tyranny. It tapped into a current of thinking about tyrannicide which went back to the killing of Julius Caesar by Brutus in 44 B.C.. William Shakespeare, for one, made it the central issue in his play about Julius Caesar which appeared in 1599. Addison was intrigued with Cato the Younger’s opposition to Caesar and his support for Roman liberty and repubicanism. This struck a chord with two opposition Whig writers, Thomas Gordon and John Trenchard, who used the nom de plume of Cato in a series of newspaper letters called Cato’s Letters which appeared between 1720-23. Addison’s influence upon other thinkers is quite impressive, including David Hume, Adam Smith, Rousseau, Voltaire, George Washington, John Adams, and many others in the late 18th century.
For further reading see the Editors' Introduction to Cato: A Tragedy and Selected Essays, ed. by Christine Dunn Henderson and Mark E. Yellin, with a Foreword by Forrest McDonald (Indianapolis: Liberty Fund, 2004).