Born in 1901, Priess volunteered for military service in the army of the German Empire in January 1919, which was transformed to the
Reichsheer in the
Weimar Republic. Due to the limitations imposed by the
Treaty of Versailles, his regiment was disbanded. He then joined the paramilitary group
Freikorps and fought in the
Estonian War of Independence. In 1920, he returned to the army and was discharged in June 1931. On 24 October 1944, Priess succeeded
Georg Keppler as commander of
I SS Panzer Corps. He led this formation, as part of the
6th Panzer Army, in the failed
Ardennenoffensive, which was dubbed the
Battle of the Bulge. The objective of the offensive was to split the British and American line in half, so the Germans could then proceed to encircle and destroy four Allied armies, forcing the
Western Allies to negotiate a
peace treaty with the Axis Powers. Subordinated to I SS Panzer Corps was
Kampfgruppe "Peiper", led by
Joachim Peiper. Peiper's command was responsible for the
Malmedy massacre, a
war crime in which 84 American
prisoners of war were murdered by their German captors near
Malmedy, Belgium. After the Ardennes offensive, the 6th SS Panzer Army was transferred to Hungary, where it fought against the advancing Soviet Army. The I SS Panzer Corps arrived in Hungary in early February 1945. There, Priess committed his forces in
Operation Southwind against the
Hron Bridgehead, a strong position formed by the Soviets over the
Danube near the town of
Esztergom, destroying the bridgehead by the end of February. He then commanded I SS Panzer Corps in
Operation Spring Awakening, the last major German offensive of World War II. The attack, centered in the
Lake Balaton area, began on 6 March 1945 and ended with a German defeat on 16 March 1945. ==War crimes trial and conviction==