With the advance of the Red Army in the spring of 1945, Sachsenhausen was prepared for evacuation. On 20–21 April the camp's SS staff ordered 33,000 inmates on a forced march northwest. Most of the prisoners were physically exhausted and thousands did not survive this death march; those who collapsed en route were shot by the SS. The march ended near Raben Steinfeld on 2 May, when 18,000 remaining prisoners were liberated by tanks of the 2nd Belorussian Front. On 22 April 1945 the camp's remaining 3,000 inmates were liberated by the Red Army and the Polish Army's 2nd Infantry Division.