The War of the First Coalition was a set of wars that several European powers fought between 1792 and 1797 initially against the constitutional Kingdom of France and then the French Republic that succeeded it. They were only loosely allied and fought without much apparent coordination or agreement; each power had its eye on a different part of France it wanted to appropriate after a French defeat, which never occurred.
Relations between the French revolutionaries with neighbouring monarchies had deteriorated following the Declaration of Pillnitz in August 1791. Eight months later, following a vote of the revolutionary-led Legislative Assembly, France declared war on Austria on 20 April 1792; Prussia, having allied with Austria in February, declared war on France in June 1792. In July 1792, an army under the Duke of Brunswick and composed mostly of Prussians joined the Austrian side and invaded France. The capture of Verdun triggered the September massacres in Paris. France counterattacked with victory at Valmy and two days later the Legislative Assembly proclaimed the French Republic.