1926, "a German seeking to avenge Germany's defeat in World War I and recover lost territory," on model of French revanchiste, which had been used in reference to those in France who sought to reverse the results of the defeat of France by Prussia in 1871 (which was accomplished by World War I).
This is from revanche "revenge, requital," especially in reference to a national policy seeking return of lost territory, from French revanche "revenge," earlier revenche, back-formation from revenchier (see revenge (v.)). Used during the Cold War in Soviet propaganda in reference to West Germany. Related: Revanchism (1954).
<a href="https://www.etymonline.com/word/revanche">Etymology of revanche by etymonline</a>
Harper, D. (n.d.). Etymology of revanche. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/revanche