From 1923–1925 Bischoff was a member of Jungwiking, the youth-wing of the Viking League, an ultra-nationalist and antisemitic paramilitary group associated with the far-right Organisation Consul movement.
During the invasion of Poland in September 1939, Bischoff served as the commander of Einsatzkommando 1/IV (a sub-unit of Lothar Beutel's Einsatzgruppe IV) which was deployed in the northern Polish territories of Pomerania, Warsaw, Białystok and Polesie.
[3] In October 1939 Einsatzgruppe IV was placed under the command of SS-Standartenführer Josef Albert Meisinger and stationed in Warsaw, where it took part in the initial round-up of the city's Jewish residents, setting in motion their eventual ghettoization.
Following the dissolution of Einsatzgruppe IV in November 1939, Bischoff was transferred to the newly annexed Polish territory of Reichsgau Wartheland and served as chief of the Gestapo for the city of Poznań (Posen).
While primarily a detention center, Fort VII also served as a regular execution site for many local Poles, Jews and the physically or mentally disabled.
[4] Bischoff was promoted to the rank of SS-Obersturmbannführer (Lieutenant Colonel) in September 1941 and returned to Germany, where he had been appointed chief of the State Police Headquarters (Staatspolizeileitstelle) in Magdeburg.
Bischoff played a central role in orchestrating the deportation of the Jews from Magdeburg and the nearby towns of Stendal, Dessau, Bernburg and Aschersleben.
[5] In December 1943 Bischoff was reassigned to the SS-Main Economic and Administrative Office (SS-WVHA) and attached to the general staff of SS-Obergruppenführer Hans Kammler, ostensibly as a representative of the Organisation Todt.
Kammler was the director of Amtsgruppe C (Buildings and Works), the organization tasked with managing the extensive civil and military engineering projects of the SS-WVHA.
Most of Germany's V-1 flying bombs and V-2 ballistic missiles were produced at Mittelwerk, a major armaments factory housed in an elaborate tunnel system in the Harz Mountains that had been built, and was partially administered, by Amtsgruppe C. The complex and dangerous work performed to assemble the V-weapons themselves was done under brutal conditions in the tunnels by thousands of slave-laborers (mainly Russians, Poles and French, among other nationalities) drawn from the inmate population of the adjunct Mittelbau-Dora concentration camp.
[6] In February 1944 the SS police and security services in the Nordhausen district (which surrounded Mittelwerk and the adjunct camp of Mittelbau-Dora) were placed under the authority of Bischoff's organization, now headquartered in Ilfeld.
[7] At Bischoff's direction, Mittelbau-Dora's Politische Abteilung (Political Department) had the leaders of the camp's Russian, French and Communist inmates rounded up in November 1944 and interned in solitary confinement.
As chief of the camp's SD, Bischoff supervised a wave of executions at Mittelbau-Dora in March 1945 that saw hundreds of prisoners, mostly Soviet POWs, killed in a series of mass-hangings.
Following the German defeat, Bischoff went into hiding in Bavaria and Hamburg before returning to Magdeburg, where he was identified and arrested by the Soviet security services in January 1946.