As the war was more often a cause of political events than a consequence, it will be convenient to follow up the progress of military affairs to the fall of Dumouriez, postponing the catastrophe of monarchy to next week.
On the 17th of February 1792 Pitt informed the House of Commons that the situation of Europe had never afforded such assurance of continued peace. He did not yet recognise the peril that lay in the new French Constitution. Under that Constitution, no government could be deemed legitimate unless it aimed at liberty, and derived its powers from the national will. All else is usurpation; and against usurped authority, insurrection is a duty. The Rights of Man were meant for general application, and were no more specifically French than the multiplication table. They were not founded on national character and history, but on Reason, which is the same for all men. The Revolution was essentially universal and aggressive; and although these consequences of its original principle were assiduously repressed by the First Assembly, they were proclaimed by the Second, and roused the threatened Powers to intervene. Apart from this inflaming cause the motives of the international conflict were indecisive. The emperor urged the affair of Avignon, the injury to German potentates who had possessions in Alsace, the complicity of France in the Belgian troubles, and the need of European concert while the French denied the foundations of European polity.
Dumouriez offered to withdraw the French troops from the frontier, if Austria would send no more reinforcements, but at that moment the queen sent word of an intended attack on Liége. The offer seemed perfidious, and envenomed the quarrel. Marie Antoinette despatched Goguelat, the man who was not at his post on the flight to Varennes, to implore intervention. She also gave Mercy her notions as to an Austrian manifesto; and in this letter, dated April 30, there is no sign of alarm, and no suggestion yet that France might be cowed by the use of exorbitant menaces. Dumouriez, who desired war with Austria, endeavoured to detach Prussia from the alliance. He invited the king to arbitrate in the Alsatian dispute, and promised deference to his award. He proposed that the prerogative should be enlarged, the princes indemnified, the émigrés permitted to return. Frederic William was unmoved by these advances. He relied on the annexation of Alsace and Lorraine to compensate both allies, and he expected to succeed, because his army was the most illustrious of all armies in Europe. He wished to restore the émigrés, who would support him against Austria, and the émigrés looked to him to set up the order of society that had fallen. "Better to lose a province," they said, "than to live under a constitution."
The allied army was commanded by the Duke of Brunswick, the most admired and popular prince of his time. His own celebrity disabled him. Many years ago Marshal Macmahon said to an officer, since in high command at Berlin, that an army is best when it is composed of soldiers who have never smelt gunpowder, of experienced non-commissioned officers, and of generals with their reputation to make. Brunswick had made his reputation under the great king, and he feared to compromise it. Want of enterprise made him unfit for his position, although nobody doubted his capacity. In France, they thought of him for the command of their armies, and even for a still higher post. In spite of the disasters I am about to describe, the Prussians believed in him, and he was again their leader when they met Napoleon. The army which he led across the Rhine fell short of the stipulated number by 35,000 men. Francis, the new emperor, did not fulfil his engagements, and entered on the expedition with divided counsels.
Kaunitz, who was eighty-two years of age, and knew the affairs of Europe better than any other man, condemned the policy of his new master. He represented that they did not know what they were going to fight for; that Lewis had never explained what changes in the Constitution would satisfy him; that nothing could be expected from disaffection, and nothing could be done for a system which was extinct. On August 2 he resigned office, and made way for men who speculated on the dismemberment of France, and expected to see a shrunken monarchy in the north and a confederate republic in the south.
The entire force brought together for the invasion amounted to about 80,000 men, of which half were Prussians. When they were assembled on the Rhine, it became necessary to explain to the French people why they were coming, and what they meant to do. Headquarters were at Frankfort, when a confidential emissary from Lewis XVI., Mallet du Pan, appeared on the scene. Mallet du Pan was neither a brilliant writer like Burke and De Maistre and Gentz, nor an original and constructive thinker like Sieyès; but he was the most sagacious of all the politicians who watched the course of the Revolution. As a Genevese republican he approached the study of French affairs with no prejudice towards monarchy, aristocracy, or Catholicism. A Liberal at first, like Mounier and Malouet, he became as hostile as they; and his testimony, which had been enlightened and wise, became morose and monotonous when his cause was lost, until the Austrian statesmen with whom he corresponded grew tired of his narrowing ideas. He settled in England, and there he died. As he was not a man likely to propose a foolish thing, he was heard with attention. He proposed that the allies should declare that they were warring on Jacobinism, not on liberty, and would make no terms until the king regained his rightful power. If he was injured, they would inflict a terrible vengeance.
Whilst Mallet's text was being manipulated by European diplomacy at Frankfort, Marie Antoinette, acting through Fersen, disturbed their counsels. The queen understood how to control her pen, and to repress the language of emotion. But after June 20 she could not doubt that another and a more violent outrage was preparing, and that the republicans aimed at the death of the king. The terms in which she uttered her belief outweighed the advice of the sober Genevese. "Save us," she wrote, "if it is yet time. But there is not a moment to lose." And she required a declaration of intention so terrific that it would crush the audacity of Paris. Montmorin and Mercy were convinced that she was right. Malouet alone among royalist politicians expected that the measure she proposed would do more harm than good. Fersen, to whom her supplications were addressed, employed an émigré named Limon to draw up a manifesto equal to the occasion, and Limon, bearing credentials from Mercy, submitted his composition to the allied sovereigns. He announced that the Republicans would be exterminated, and Paris destroyed. Already Burke had written: "If ever a foreign prince enters into France, he must enter it as into a country of assassins. The mode of civilised war will not be practised; nor are the French, who act on the present system, entitled to expect it." Mallet du Pan himself had declared that there ought to be no pernicious mercy, and that humanity would be a crime. In reality, the difference between his tone and the fanatic who superseded him was not a wide one.
The manifesto, which proceeded from the queen, which had the sanction of Fersen, of Mercy, of Bouillé, was accepted at once by the emperor. The Prussians introduced some alterations, and Brunswick signed it on July 25. His mind misgave him at the time, and he regretted afterwards that he had not died before he set his hand to it. Mercy, when it was too late, wished to put another declaration in its place. The Prussian ministers would not suffer the text to be published at Berlin. They allowed the author to fall into poverty and obscurity. He had acted in the spirit of the émigrés.
On July 27 the Princes issued a declaration of their own, to the effect that not Paris only should suffer the extremity of martial law, but every town to which the king might be taken if he was removed from the capital. Breteuil, although he complained that the invaders exhibited an intolerable clemency, disapproved the second proclamation. But Limon demanded the destruction of Varennes, and the émigrés expected that severities should be inflicted on the population as they went along. The idea of employing menaces so awful as to inspire terror at a distance of 300 miles was fatal to those who suggested it; but the danger was immediate, and the consequences of inaction were certain, for the destined assailants of the Tuileries were on the march from Toulon and Brest. It was not so certain that the king would be unable to defend himself. The manifesto was a desperate resource in a losing cause, and it is not clear that wiser and more moderate words would have done better. The text was not published at Paris until August 3. The allies were too far away for their threats to be treated seriously, and they are not answerable for consequences which were already prepared and expected. But their manifesto strengthened the hands of Danton, assured the triumph of the violent sections, and suggested the use to which terror may be put in revolutions. It contributed to the fall of the monarchy, and still more to the slaughter of the royalists three weeks later. The weapon forged by men unable to employ it was adopted by their enemies, and served the cause it was intended to destroy.