Marlene Dietrich’s war days were in the remote past when this came out in 1959. My guess is she was trying to cash in on the success of the war song Lili Marleen, the song she was singing for the troops during the European campaign of the US army in the Second World War.
The song itself is a bit older, and not originally sung by Dietrich. The words were written by a schoolteacher in 1915. He got the name from two different girls, both of them not his own girlfriend. It was published in 1937 and quickly put to music by Lale Andersen in 1939.
During the war, the song was popular among soldiers on both American and German sides. It was used as a propaganda song for each side, beginning in 1941 by the German radio station in Belgrade. For the Americans it was Marlene Dietrich incessantly touring for the troops, supposedly on rickety stages. She changed the title slightly to fit her own: Marleen became Marlene.
After war the song stayed popular. More than two hundred artists have tried their hands at it, from singer songwriters and jazz to punk bands. Most of them followed Dietrich in calling the song Lili Marlene.