1933, he left the army having attained the rank of major. SS career Steiner first joined the Nazi Party (NSDAP) (membership number: 4,264,295) and the Sturmabteilung (SA). In 1935 he enlisted in the SS. He took command of a battalion of SS-Verfügungstruppen (SS-VT) troops, and within a year had been promoted to SS-Standartenführer; and later was put in command of the SS-Deutschland Regiment. At the outbreak of World War II, he was SS-Oberführer (senior leader) in charge of the Waffen-SS regiment SS-Deutschland. He led this regiment through the Invasion of Poland and the Battle of France, for which he was awarded the Knight's Cross of the Iron Cross on 15 August 1940. Steiner was introduced to Heinrich Himmler, the head of the SS, to oversee the creation of, and then command the new SS Division Wiking. This division was militarily successful but also very barbaric in the invasion of the Soviet Union, for example killing 600 Jews in Zboriv, Ukraine. At the time of its creation, the division consisted mostly of non-German volunteers (Dutch, Flemish, Finns and Scandinavians), including the Danish regiment Frikorps Danmark. In April 1943, he was placed in command of a newly formed III SS Panzer Corps. The unit participated in anti-partisan actions in Yugoslavia. In November/December 1943 his corps was transferred to the Eastern Front and positioned in the northern sector at Leningrad under Army Group North. Steiner's Panzer Corps played a leading role during the Battle of Narva and the Battle of Tannenberg Line. His unit then withdrew with the rest of Army Group North to the Courland Peninsula. Battle of Berlin In January 1945, Steiner along with the III SS Panzer Corps was transferred by ship from the Courland Pocket to help with the defence of the German homeland. The corps was assigned to Army Group Vistula under the new Eleventh SS Panzer Army although the army really existed only on paper. Once the Soviet Army had reached the Oder River, the Eleventh SS Panzer Army became inactive, and the III SS Panzer Corps was reassigned to the German Third Panzer Army as a reserve during the Soviets' Berlin Offensive Operation. During the Battle of Seelow Heights, the first major battle of the offensive, General Gotthard Heinrici, the commander of Army Group Vistula, transferred most of the III SS Panzer Corps' divisions to General Theodor Busse's Ninth Army. By 21 April, Soviet Marshal Georgi