Correct, after Wolfgang Preiss played von Stauffenberg in 1955 (already!), he was almost in every international movie production the prototype of an upright, dutiful and honest German military officer. An English director once said, he was often playing an enemy you could almost love.
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Curd Jürgens (or "Curt" in some productions, because of the name similarity with which we Germans call "Quark") usually played the more problematic characters, never really evil, but psychologically torn between their claims to themselves and the dishonest and dishonorable reality. In "The Devil's General", he played very well one of the most famous German first aviators and knight like heros from WW I, who became general under Hitler: Ernst Udet.
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But when I think of Curd Jürgens, my first thought is a part of this movie because I love satirical comedies with a serious background so much:
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In this movie, Jürgens played the Polish Colonel Prokoszny with a "Samurai"-like attitude to war - always on the brink of committing a suicide of honour. Danny Kaye played the Jewish refugee Jacobowsky with the attitude that you always have two possibilities in life and although they both rather hate each other, they have to work together in order to escape the advancing German troops in France.
Well, in any case, in the scene I will remember for all my life, Jürgens as Prokoszny tells his French girl-friend as he always told all other of his girl-friends and every woman who ever helped him: "In the cathedral of my heart, there will always be a candle burning for you!"
After Jacobowsky heard this kind of flirting several times, he is shaking his head and murmurs in the background: "This must be the most brightly lit place of worship in Europe!"
But in the successful end for both, even Jacobowsky tells the Polish colonel when they are saying good-bye to each other: "In the synagogue of my heart, there will always be a candle burning for YOU!"