Levée en masse is a French term used for a policy of mass national conscription, often in the face of invasion.

Conscription is the state-mandated enlistment of people in a national service, mainly a military service. Conscription dates back to antiquity and it continues in some countries to the present day under various names. The modern system of near-universal national conscription for young men dates to the French Revolution in the 1790s, where it became the basis of a very large and powerful military. Most European nations later copied the system in peacetime, so that men at a certain age would serve 1 to 8 years on active duty and then transfer to the reserve force.