Career
Henning enlisted as an officer in the German Imperial Army in 1879 and remained until 1919 when he retired with the rank of Major. From 1917 he served in the War Ministry and was moved to Street St. Petersburg in 1918. Entering politics, Henning joined the conservative German National People"s Party (DNVP) and was elected to the Reichstag in 1920.
From the start Henning was on the extreme anti-Semitic and was close to the likes of Albrecht von Graefe, Reinhold Wulle and Richard Kunze, although the latter split from the DNVP in 1921 to form his own Deutschsoziale Partei.
Rathenau controversy
Henning became notorious for an article of his that appeared in the June 1922 edition of Konservative Monatsschrift. In the article, "The Real Face of Rapallo Terror", Henning denounced Walther Rathenau as an "international Jew" who had sullied German honour by not mentioning the murder of envoy Wilhelm Graf von Mirbach-Horff in Moscow during the Treaty of Rapallo negotiations.
During the struggles for the leadership of the Völkisch movement between the DVFP and the Nazis Henning had been a strong critic of Adolf Hitler and had denounced him as "not a politician". Despite this he would go one to serve as a Nazi Party member after the collapse of the DVFP. Henning also served as the deputy chairman of the Verband nationalgesinnter Soldaten, a right-wing veterans organisation active in the 1920s.