It took two decades before Napoleon briefly justified Chaumette's prediction, minus the Jacobin ingredient. Initially, the Rhineland enjoyed strategic and ideological front-line status following the French declaration of war on Austria in April 1792. The Austrians and Prussians first held the initiative, advancing and capturing Verdun on 2 September. Then the French, under Dumouriez, managed to redeploy and block the Prussians at Valmy (20 September), a battle that condemned Europe to a generation of war. The French, exploiting their numerical superiority, followed up Valmy by invading the Reich: one army, under Custine, entered the Palatinate, whose cities fell quickly, whilst a second, under Dumouriez, advanced into the Netherlands, pushed aside the Austrians at Jemappes (6 November), captured Brussels and invaded the Lower Rhine.

As the situation deteriorated, Austria attempted to mobilise the military potential of the Holy Roman Empire. This proved difficult. Officially, France was not at war with the Reich, as she had declared war on the Habsburgs as kings of Hungary. The Reich as a whole lacked the internal consensus to resort to force, and this French diplomats exploited. Opposition to the war was led by France's old allies, the Wittelsbachs, but was a sentiment that extended widely. In electoral Cologne domestic opposition to war from the estates prevented mobilisation.