A Lesson Not Learned (1971)

This film was made in reaction to revanchism fear that Germany would reunite and seek revenge on Europe and the USSR for World War II. A disguised Nazi slips into the US zone of divided Germany. The Americans nurse him back to health as he plots how to reunite the Fatherland. His plans are ruined when he runs headlong into the Berlin Wall, erected by the USSR between East and West Berlin in 1961.

Unfortunately the movie A Lesson Not Learned is not yet available on HBO Max.