On the 3rd of December, 1791 (to quote a fundamental date in the rapid progress towards the war which was to transform the Revolution), the King—writing in a manner which betrays dictation by his wife—begged the King of Prussia (as she had begged the Emperor) to mobilise an armed force, and with it to back a Congress that should have for its object the prevention of the spread of the Revolution. That letter was typical of the moment. From both sides tension was rapidly proceeding to the breaking point. Nor was the tension merely upon generalities. The Revolution had broken a European treaty in the annexation of the Papal State of Avignon, and it had broken European conventions when it had abolished in Alsace feudal rights that were possessed by the princes of the empire. It was as though some State to-day, attempting Collectivism, should confiscate, along with other property, securities lying in its banks, but held by the nationals of a foreign State.
On the revolutionary side also there was a definite point at issue, which was the permission accorded within the empire for the emigrants to meet in arms and to threaten the French frontier.
But these precise and legal points were not the true causes of the war. The true causes of the war were the desire of the unreformed European Governments (notably those of Prussia and Austria) that the Revolution should, in their own interests, be checked, and the conviction that their armed forces were easily capable of effecting the destruction of the new French régime.
The Court of Vienna refused to accept a just indemnity that was offered the princes of the empire in Alsace for the loss of their old feudal rights; Leopold, the emperor, who was one of the same generation as the French King and Queen, died upon the 1st of March, 1792, and was succeeded by a son only twenty-four years of age and easily persuaded to war.
On the French side, with the exception of the Mountain and notably of Robespierre, there was a curious coalition of opinion demanding war.
The Court and the reactionaries were sufficiently certain of the victory of the Allies to find their salvation in war.
The revolutionary party, that is, the mass of public opinion and the “patriots,” as they called themselves, the Girondins, also, and especially, desired war as a sort of crusade for the Revolution; they suffered grievous illusions, as enthusiasts always must, and believed the French armed forces capable of sustaining the shock. The plans had already been drawn up for the campaign (and promptly betrayed to the enemy by the Queen); Dumouriez, an excellent soldier, had from the middle of March 1792 been the chief person in the ministry, and the director of foreign affairs, and a month later, on the 20th of April, war was declared against Austria, or, to be accurate, against “the King of Hungary and Bohemia.”
Such was still the official title of Marie Antoinette’s nephew, who, though now succeeded to the empire, had not yet been crowned emperor. It was hoped to confine the war to this monarch, and, indeed, the German princes of the empire did not join him (the Landgrave of Hesse-Cassel was an exception). But the one German power that counted most, the kingdom of Prussia, which Dumouriez had especially hoped to keep neutral, joined forces with Austria. The royal letters had done their work.
At this critical moment the French armed forces and the French strongholds were at their worst. The discipline of the army was deplorable. The regular soldiers of the old régime had lost from six to nine thousand officers by emigration, and mixed no better than water and oil with the revolutionary volunteers who had been drafted (to the number of over two hundred battalions) into the ranks of the army; moreover, these volunteer battalions were for the most part ill provided, far below their establishment, some only existed on paper; none were trained as soldiers should be trained. In a more orderly time, when the decrees of the Government corresponded with reality, four hundred thousand men would have held the frontier; such a number was in the estimates. As it was, from the Swiss mountains to the English Channel, the French could count on no more than one-fifth of that number. Eighty thousand alone were under arms. The full Prussian army was, alone, apart from its allies, close upon treble the size of this disorganised and insufficient force.
Panics at once ludicrous and tragic opened the campaign upon the French side. The King took advantage of them to dismiss his Girondin Ministry and to form a reactionary Government. The Parliament replied by measures useless to the conduct of war, and designed only to exasperate the Crown, which was betraying the nation. It ordered the dismissal of the royal Guard, the formation of a camp of revolutionary Federals outside Paris, the transportation of the orthodox priests; in pursuit of the Court’s determination to resist the Assembly and to await the victorious allies, Louis vetoed the last two decrees. La Fayette, who was now in command of the army of the centre, with his headquarters at Sedan, right upon the route of the invasion, declared for the King.