The Quadruple Alliance was formed by the monarchist Great Powers of Austria, Prussia, Russia, and Great Britain to counter the military and revolutionary republican political threats posed by the expansion of the First French Empire under Napoleon I and to fight the War of the Seventh Coalition. In the wake of the final defeat of Napoleon at the Battle of Waterloo on 18 June 1815, the alliance was formalized with the signing of the Treaty of Paris on 20 November 1815. It renewed the use of the Congress System which sought to stabilize European international relations at the time and pledged each signatory to a military alliance that ultimately aimed to crush any recurrence of revolutionary outbreaks like those that led to the French Revolution if they occurred anywhere in Europe. The quadr