Revanchism is a policy of seeking to retaliate, especially to recover lost territory. 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.
Extreme revanchist ideologues often represent a hawkish stance, suggesting that their desired objectives can be achieved through the positive outcome of another war. Revanchist justifications are often presented as based on ancient occupation of a territory.
The instance of revanchism that gave these groundswells of opinion their modern name came in the 1870s. French revanchism was a deep sense of bitterness, hatred and demand for revenge against Germany, especially because of the loss of Alsace and Lorraine following defeat in the Franco-Prussian War.
Georges Clemenceau, of the Radical Republicans, opposed participation in the scramble for Africa and other adventures that would divert the Republic from objectives related to the "blue line of the Vosges" in Alsace-Lorraine. After the governments of Jules Ferry had pursued a number of colonies in the early 1880s, Clemenceau lent his support to Georges Ernest Boulanger, a popular figure, nicknamed Général Revanche, who it was felt might overthrow the Republic in 1889. This ultranationalist tradition influenced French politics up to 1921 and was one of the major reasons France went to great pains to woo the Russian Empire, resulting in the Franco-Russian Alliance of 1894 and, after more accords, the Triple Entente of the three great Allied powers of World War I: France, Great Britain, and Russia.
French revanchism influenced the Treaty of Versailles of 1919 following the end of World War I, which restored Alsace-Lorraine to France and extracted reparations from the defeated Germany. The conference was not only opened on the anniversary of the proclamation of the "Second Reich", the treaty also had to be signed by the new German government in the same room, the Hall of Mirrors.
A German revanchist movement developed in response to the losses of World War I. Pan-Germanists within the Weimar Republic called for the reclamation of the property of a German state due to pre-war borders or because of the territory's historical relation to Germanic peoples. The movement called for the reincorporation of Alsace-Lorraine, the Polish Corridor and the Sudetenland (see Bohemia, Moravia, Silesia—parts of the Austrian Empire and Austria-Hungary until its dismemberment after World War I). Those claims, supported by Adolf Hitler, led to World War II, with the invasion of Poland. This irredentism had also been characteristic of the Völkisch movement in general and of the Pan-German League (Alldeutsche Verband). The Verband wanted to uphold German 'racial hygiene' and were against breeding with so-called inferior races like the Jews and Slavs.