Pospolite ruszenie (Polish pronunciation: [pɔspɔˈlitɛ ruˈʂɛɲɛ], lit. mass mobilization; "Noble Host",Latin: motio belli, the French term levée en masse is also used) is a name for the mobilisation of armed forces during the period of the Kingdom of Poland and the Polish-Lithuanian Commonwealth. The tradition of wartime mobilisation of part of the population existed from before the 13th century to the 19th century. In the later era, pospolite ruszenie units were formed from the szlachta (Polish "nobility"). The pospolite ruszenie was eventually outclassed by professional forces.
Before the 13th century, the feudal levy of knights was the customary method employed in the raising of Polish armies in the Kingdom of Poland of the Late Middle Ages. The earliest mentions of the term can be traced to the reign of Władysław I the Elbow-high (1320–1333).Statutes of Casimir the Great made the service in the military obligatory for all knights-landowners, under the penalty of land confiscation. The more wealthy knights provided a lances fournies unit (known in Poland as kopia), and the less prosperous ones served as a light horseman or even infantryman. They were obliged to take arms and defend the country, and to participate in wars in foreign lands.