When the National Constituent Assembly dissolved itself on 3 September 1791, it decreed as a final measure that King Louis XVI should have a Constitutional Guard, also known as the garde Brissac after its commander Louis Hercule Timolon de Cossé, duc de Brissac. This guard's formation was the only court reform to be put into effect, but it only lasted a few months, being superseded by the National Guard.
Formerly created on 16 March 1792 and numbering 1200 infantry and 600 cavalry, the Constitutional Guard provided a substantial force expected to ensure the security of the constitutional monarchy in the event of any uprising in Paris. It was recruited from a mixture of regular soldiers with good service records and selected volunteers. Members of the former Regiment of French Guards (which had mutinied immediately before the storming of the Bastille) were specifically excluded from the new corps.
The new force was stationed in and near to the Tuileries palace. Queen Marie-Antoinette had asked that it be uniformed in sky-blue but the conservative politician Antoine Barnave was able to persuade her that this apparently minor measure would lead to confusion with the German mercenary regiments of the former Royal Army. The Constitutional Guard was accordingly issued with the dark blue coats of the French National Guard.
Although the new corps had been organized and sworn in according to the requirements of the Constitution of September 1791, it almost immediately became the object of suspicion and hostility by the growing revolutionary movement. There were street brawls between guardsmen and anti-monarchists, and revolutionary newspapers inaccurately described the Constitutional Guard as being made up of aristocrats. This appears to have been an attempt to link the new guard with its predecessor - the recently disbanded Bodyguard, which had been recruited solely from members of the nobility.
On 29 May 1792 the Constitutional Guard was disbanded. This measure was undertaken following a formal request from the Legislative Assembly addressed to King Louis, whose position had been weakened following the abortive flight to Varennes. He hoped by concurring in the dissolution of his guard to win support for several vetoes that he wished to impose on measures aimed at the deportation refractory priests and the establishment of a military camp for provincial militias near Paris.
The Constitutional Guard was replaced by units of the Paris National Guard, who took over responsibility for the security of the Tuileries palace and the royal family resident there. Lacking any particular commitment of loyalty to the monarchy, the National Guard was to prove unreliable when the Tuileries was finally stormed by revolutionary forces on 10 August 1792. The Duc de Brissac was arrested on charges of planning to use his guardsmen against the Assembly, and subsequently killed during the September Massacres that followed.