"Levee en Masse" is declared in France
The first modern use levée en masse occurred during the French Revolutionary Wars.
Under the Ancien Régime, there had been some conscription (by ballot) to a militia, milice, to supplement the large standing army in times of war. This had proven unpopular with the peasant communities on which it fell and was one of their grievances which they expected to be addressed by the French States-General, when it were convened in 1789 to put the French monarchy on a sounder footing. When this led instead to the French Revolution, the milice was duly abolished by the National Assembly.
The progression of the Revolution came to produce friction between France and its European neighbors, who grew determined to invade France to restore the monarchical regime. War with Prussia and Austria was declared in April 1792. The invading forces were met in France by a mixture of what was left of the old professional army and volunteers (it was these, not the levée en masse, that won the battle of Valmy in September 1792).
By February 1793 the new regime needed more men, so the National Convention passed a decree on 14 February allowing for the a national levy of about 300,000 with each French département to supply a quota of recruits. By March 1793 France was at war with Austria, Prussia, Spain, Britain, Piedmont and the United Provinces. The introduction of recruitment for the Levy in the Vendée, a political and religiously conservative region, added to local discontent over other revolutionary directives emanating from Paris, and on 11 March the Vendée erupted into civil war—just days after France declared war on Spain and adding further strains on the French armies' limited manpower. By some accounts, only about half this number appears to have been actually raised, bringing the army strength up to about 645,000 in mid-1793, and the military situation continued to worsen.
In response to this desperate situation, at war with European states, and insurrection, a levée en masse was decreed by the National Convention on 23 August 1793. All unmarried able-bodied men between 18 and 25 were requisitioned with immediate effect for military service.
From this moment until such time as its enemies shall have been driven from the soil of the Republic, all Frenchmen are in permanent requisition for the services of the armies. The young men shall fight; the married men shall forge arms and transport provisions; the women shall make tents and clothes and shall serve in the hospitals; the children shall turn old lint into linen; the old men shall betake themselves to the public squares in order to arouse the courage of the warriors and preach hatred of kings and the unity of the Republic.”— 1793 levee en masse