Marlene's German lyrics closely follow the very simple English ones. Test your German familiarity. I do like one distinction, however:
Wann wird man je verstehen, [When will they ever learn,]
Wann wird man je verstehen? [When will they ever learn?]
The original phrase "when will they ever learn" grates on me because it blames others for the human condition. In the context of the original song, it was very much an "us vs. them" mentality. According to Pete Seeger and a very eager postwar generation, war was what other people did. Nowadays, war is what the US does; "others" are freedom fighters. The German version is one step closer to the truth and Google is a full measure closer to the truth:
Not "when will they ever learn"; not "when will one ever learn"; but rather -- when will we ever learn? It's the pronoun, you see.
Pete Seeger is credited with writing most of the song, but a lesser-known songwriter named Joe Hickerson (who is still alive?) nearly perfected it by turning the song into a circle. Another example of such a circular song is Zager and Evans' "In The Year 2525." Can anyone think of others?
The song is also an example of a now rare artistic device called Ubi Sunt.