Franz Oppenhoff (18 August 1902 – 25 March 1945) was a German lawyer who was appointed mayor of the city of Aachen after its capture by Allied forces in World War II.

Oppenhoff was an expert on Nazi law, had been legal representative for the Bishop of Aachen, Johannes Joseph van der Velden, and had defended some cases for Jewish companies.

Assisted by the Bishop of Aachen, officials managed to make contact with a group of local business people, one of whom was willing to become the first German mayor under American rule.

[1] Also, earlier in October the SS newspaper, Das Schwarze Korps, had written that there would be no German administration under the occupation because any official who collaborated with the enemy could count on being dead within a month.

[2] In December 1944 a group of officers belonging to the US Army's Psychological Warfare Division, coordinated by historian Saul K. Padover, arrived in Aachen to assess the German population's political views and their attitude to the Nazis and the local situation.

In January 1945 Padover claimed that he had discovered a "wholesale political conspiracy" in the city, centering on Oppenhoff, whose purpose was to keep left-wing forces out of stewardship.

[1] Padover saw to it that his story was leaked to the press so as to create sufficient uproar in the American public, and a purge of the city administration resulted, to expel former Nazis.

Ilse Hirsch, a 23-year-old Nazi youth leader,[4] a Hauptgruppenführerin (captain) in the League of German Girls (BDM) was supposed to provide supplies, but turned out to play an important part in the operation.