Lt. Karl-Heinz Reintgen was an officer in the German Army, with the rank of lieutenant during World War II.
He was in charge of the German Army's radiostation Radio Belgrade, situated in Belgrade, Yugoslavia. He is credited with making the tune "Lili Marleen" by Lale Anderson a war-time theme for troops on both sides by playing it every evening at 9.55 PM.
References
Karl-Heinz Reintgen Wikipedia(Text) CC BY-SA