Revanchism (French: Revanchisme, from revanche, "revenge") is the political manifestation of the will to reverse territorial losses incurred by a country, often following a war or social movement. As a term, revanchism originated in 1870s France in the aftermath of the Franco-Prussian War among nationalists who wanted to avenge the French defeat and reclaim the lost territories of Alsace-Lorraine.
Revanchism draws its strength from patriotic and retributionist thought and is often motivated by economic or geopolitical factors. Extreme revanchist ideologues often represent a hawkish stance, suggesting that their desired objectives can be achieved through the positive outcome of another war. It is linked with irredentism, the conception that a part of the cultural and ethnic nation remains "unredeemed" outside the borders of its appropriate nation-state.
Revanchist politics often rely on the identification of a nation with a nation state, often mobilizing deep-rooted sentiments of ethnic nationalism, claiming territories outside the state where members of the ethnic group live, while using heavy-handed nationalism to mobilize support for these aims. Revanchist justifications are often presented as based on ancient or even autochthonous occupation of a territory since "time immemorial", an assertion that is usually inextricably involved in revanchism and irredentism and justifies them in the eyes of their proponents.