The constitution of 1791 lasted less than a year. War, distrust of the king and the pressure of the Paris streets pushed the revolution into a republic and then into a fight for survival.
Choosing war
The new Legislative Assembly met in October 1791. Nobles who had fled abroad, the émigrés, gathered in the Rhineland, and in August 1791 the rulers of Austria and Prussia had issued the Declaration of Pillnitz, a vague threat to intervene. A group of deputies around Jacques Pierre Brissot, later called the Girondins because several came from the Gironde, made the case for war. The Girondins argued that war would spread liberty abroad and expose traitors at home; peoples living under kings, they said, would welcome French armies. Robespierre disagreed, warning that "no one loves armed missionaries." Louis XVI also wanted war, for his own reasons: he hoped defeat would bring back his power. On 20 April 1792 France declared war on Austria, and Prussia soon joined. The first campaigns went badly.
The fall of the monarchy
In July the Prussian commander issued the Brunswick Manifesto, threatening Paris with destruction if the royal family were harmed. It enraged rather than frightened. On 10 August 1792 crowds stormed the Tuileries Palace, where the royal family lived, killing hundreds of the king's Swiss Guards, and the Assembly suspended the king. The attackers included National Guards from the provinces, among them volunteers from Marseille who brought a new marching song, and above all the sans-culottes. The name means "without knee breeches," the silk garment of the well off. The sans-culottes were working Parisians such as artisans and shopkeepers, organized in the city's 48 sections, who wanted bread at fair prices, harsh treatment of traitors and a direct voice in politics.
September
With Prussian troops advancing and the fortress of Verdun fallen, fear gripped Paris. In early September crowds broke into the city's prisons and, after improvised trials, killed roughly 1,100 to 1,400 prisoners, most of them ordinary criminals, along with priests and nobles. These September Massacres horrified opinion across Europe. Weeks later, on 20 September, the French army stopped the Prussians at Valmy. Goethe, who watched from the Prussian side, later wrote: "From this place, and from this day forth, commences a new era in the world's history."
The Republic and the king's trial
A new assembly, the National Convention, was elected with nearly all adult men entitled to vote, though turnout was low. On 21 September 1792 the Convention abolished the monarchy, and the next day became the first day of Year I of the Republic. In December the Convention put "Louis Capet" on trial. Saint-Just, aged 25, argued that "no man can reign innocently." The deputies found Louis guilty with near unanimity, voted narrowly for death, and rejected a reprieve. He was guillotined on 21 January 1793. The Girondins had tried to delay; the radical deputies of the Mountain, named for their high seats, insisted.
The crisis of 1793
By spring France was at war with Britain, the Dutch Republic and Spain as well. In March the Vendée revolt was sparked by a call to conscript 300,000 men; in that western region peasants who resented the attacks on their priests refused to fight for Paris and rose in arms. The general Dumouriez defected to the Austrians in April. The Convention created a Revolutionary Tribunal and, in April, a Committee of Public Safety. On 2 June armed sans-culottes surrounded the Convention and forced the arrest of 29 Girondin deputies. Lyon, Marseille, Bordeaux and other cities rose against Paris in the "federalist" revolts. In July Charlotte Corday stabbed the radical journalist Jean-Paul Marat in his bath.
In August the Convention decreed the levée en masse, mobilizing the whole nation for war: "The young men shall go to battle; the married men shall forge arms and transport provisions; the women shall make tents and clothes and shall serve in the hospitals." Within a year the French army was the largest Europe had seen, and the idea of a nation in arms would shape warfare for the next two centuries.
Worked example: Robespierre against the war
Over the winter of 1791 to 1792 the Jacobin Club hosted a long debate. Brissot's case: the revolution is surrounded by hostile monarchs and a disloyal court; a war fought now, on France's terms, will rally patriots, unmask traitors and carry freedom to peoples who want it. Robespierre's case: foreigners do not welcome liberty delivered at bayonet point; the real enemies are at home; and war hands power to generals, who may one day turn it against the people.
Judge each case by what followed. Brissot was right that war would rally the nation and unmask the king, but wrong that it would be short or welcomed. Robespierre was right that war would empower generals, a warning Napoleon later fulfilled, though he himself would use the emergency of war to justify the Terror. Arguments about war often look like this: each side sees one real danger clearly and underrates the other.