Sachsenhausen () or Sachsenhausen-Oranienburg was a German Nazi concentration camp in Oranienburg, Germany, used from 1936 until April 1945, shortly before the defeat of Nazi Germany in May later that year. It mainly held political prisoners throughout World War II. Prominent prisoners included Joseph Stalin's oldest son, Yakov Dzhugashvili; assassin Herschel Grynszpan; Paul Reynaud, the penultimate Prime Minister of France; Francisco Largo Caballero, Prime Minister of the Second Spanish Republic during the Spanish Civil War; the wife and children of the Crown Prince of Bavaria; Ukrainian nationalist leader Stepan Bandera; and several enemy soldiers and political dissidents. Sachsenhausen was a labor camp, outfitted with several subcamps, a gas chamber, and a medical experimentation area. Prisoners were treated inhumanely, fed inadequately, and killed openly. After World War II, when Oranienburg was in the Soviet Occupation Zone, the structure was used by the NKVD as NKVD special camp Nr. 7. Today, Sachsenhausen is open to the public as a memorial. Sachsenhausen under Nazi Germany The camp was established in 1936. It was located north of Berlin, which gave it a primary position among the German concentration camps: the administrative centre of all concentration camps was located in Oranienburg, and Sachsenhausen became a training centre for Schutzstaffel (SS) officers (who would often be sent to oversee other camps afterwards). Initially, the camp was used to perfect the most efficient and effective execution method for use in the death camps. Given that, executions obviously took place at Sachsenhausen, especially of Soviet prisoners of war. During the earlier stages of the camp's existence, the executions were done by placing the prisoners in a small room, often even with music playing, called the Genickschussbaracke and told they were to have their height and weight measured but were instead shot in the back of the neck through a sliding door located behind the neck. This was found to be far too time-consuming, so they then trialled a trench, killing either by shooting or by hanging. While this more easily enabled group executions, it created too much initial panic among the prisoners, making them harder to control. Then small scale trials of what would go on to become the large scale, death camp gas chambers were designed and carried out. These trials showed the authorities that this method facilitated the means to murder the largest number of prisoners without "excessive" initial panic. So by September 1941, when they