Complex sentence: For unknown reasons, he was drafted shortly before World War II to be specific, on 28 August 1939 by the Gestapo when Schelcher was arrested and enlisted as a soldier and was "probation battalion assigned".
Split into simpler sentences: For unknown reasons, he was drafted shortly before World War II on 28 August 1939 by the Gestapo. When Schelcher was arrested he was enlisted as a soldier and was "probation battalion assigned".