While the revolutionary government frantically raised fresh troops and reorganised its armies, a Prussian-Austrian army under Charles Wilhelm Ferdinand, Duke of Brunswick assembled at Coblenz on the Rhine. In July, the invasion began, with Brunswick’s army easily taking the fortresses of Longwy and Verdun.
The duke then issued a proclamation called the Brunswick Manifesto, on July 25, 1792. It was written by Louis XVI’s émigré cousin, Louis-Charles the Prince de Condé, declaring the intent of the Austrians and Prussians to restore the king to his full powers and to treat any person or town who opposed them as rebels to be condemned to death by martial law.
King Louis XVI of France and Navarre
Contrary to its intended purpose of strengthening Louis XVI’s position against the revolutionaries, the Brunswick Manifesto had the opposite effect of greatly undermining his already highly tenuous position. It was taken by many to be the final proof of collusion between the king and foreign powers in a conspiracy against his own country.
The anger of the populace boiled over on August 10, when an armed mob – with the backing of a new municipal government of Paris that came to be known as the Insurrectional Paris Commune – marched upon and invaded the Tuileries Palace. The royal family took shelter with the Legislative Assembly.
Louis XVI was officially arrested on August 13, 1792 and sent to the Temple, an ancient fortress in Paris that was used as a prison. On September 21, the National Assembly declared France to be a Republic, and abolished the monarchy. Louis was stripped of all of his titles and honors, and from this date was known as Citizen Louis Capet.
The Girondins were partial to keeping the deposed king under arrest, both as a hostage and a guarantee for the future. Members of the Commune and the most radical deputies, who would soon form the group known as the Mountain, argued for Louis’s immediate execution.
Louis XVI imprisoned at the Tour du Temple
The legal background of many of the deputies made it difficult for a great number of them to accept an execution without the due process of law, and it was voted that the deposed monarch be tried before the National Convention, the organ that housed the representatives of the sovereign people.
In many ways, the former king’s trial represented the trial of the monarchy by the revolution. It was seen as if with the death of one came the life of the other. The historian Jules Michelet later argued that the death of the former king led to the acceptance of violence as a tool for happiness. He said, “If we accept the proposition that one person can be sacrificed for the happiness of the many, it will soon be demonstrated that two or three or more could also be sacrificed for the happiness of the many. Little by little, we will find reasons for sacrificing the many for the happiness of the many, and we will think it was a bargain.”
Louis was then tried by the National Convention, found guilty of high treason, and executed by guillotine on January 21, 1793, as a desacralized French citizen under the name of Citizen Louis Capet, in reference to Hugh Capet, the founder of the Capetian dynasty – which the revolutionaries interpreted as Louis’ surname. Louis XVI was the only King of France ever to be executed, and his death brought an end to more than a thousand years of continuous French monarchy.