Русский корпус
After occupation of the Kingdom of Yugoslavia by Nazi Germany in April 1941, Shteifon was offered a position of chief of staff of the Russian Corps organized in Belgrade on 12 September by the Germans on the initiative of former Russian general Mikhail Skorodumov and became its commander three days later. Until the spring of 1944, the principal task of the Russian Corps, which was mainly composed of former servicemen of the Russian Imperial Army and the White Army, was to guard certain sites and areas from the Communist partisans led by Josip Broz Tito, who were supported by the USSR and later in the war also by Britain; in 1944 the Corps was actively engaged in fighting against Tito′s partisans; and finally, from September 1944, after the previously Germany-allied Romania and Bulgaria switched sides and regular units of the Red Army advanced into the Western Balkans, the Corps also fought against the regular Soviet troops in Serbia and later in what is now Croatia.