On November 14, 1939 he joined the 12th SS Totenkopf Standarte in Łódź, which shot a thousand residents of the psychiatric hospital in Owinsk near Poznań.

[2] He participated in so called operations against "partisans", which meant the execution of Polish intellectuals and Jews.

[2] Prior to Operation Barbarossa he came to the Leibstandarte, and commanded its 13th (heavy) company of Tiger I tanks.

[2] As an ardent Nazi, Kling was popular among his fellow Waffen-SS soldiers.

[3] Since late November 1943 the SS Panzer Regiment 1 was commanded by Joachim Peiper, of whom Kling was a personal favorite.