Other monarchies in Europe had been watching the developments in France with alarm as early as 1791, and have considered intervening, either in support of Louis XVI or to take advantage of the chaos in France.

The ideological differences between France and the monarchical powers of Europe are compounded by continuing disputes over the status of Imperial estates in Alsace, and the French are becoming concerned about the agitation of émigré nobles abroad, especially in the Austrian Netherlands and the minor states of Germany.

In the end, France, charging Austria with sponsoring counterrevolutionary agitation, declares war on Austria first, with the Assembly voting for war on April 20, 1792, after the presentation of a long list of grievances by Charles François Dumouriez, who had joined the French Revolution following army service under the monarchy and become foreign minister in March.

Louis XVI, hoping for Austrian intervention, vetoes emergency measures.