According to Ute Deichmann's book Biologists under Hitler, in 1942 he became director of a unit affiliated with the Central Cancer Institute at the University of Posen (Poznań in Poland, annexed by Germany in 1939).

In 1943, Schumann wrote to Dr. Heinrich Kliewe, one of the Wehrmacht's biological warfare experts that "in particular, America must be attacked simultaneously with various human and animal epidemic pathogens as well as plant pests.

"[5] According to Kliewe, plague, typhoid, cholera and anthrax were being developed as weapons, as well as a new "synthetic medium for the spread of these bacteria" which would allow them to remain virulent for eight to twelve weeks.

By May 1944, the institute had sections devoted to physiology-biology, bacteriology and vaccines, radiology, pharmacology, cancer statistics and a tumor farm, and had received at least 2.7 million Reichsmarks in funding from the Wehrmacht and S.S. in 1943–45.

At the University of Strassburg, a "special unit" headed by Prof. Eugen von Haagan and employing researchers like Kurt Gutzeit and Arnold Dohmen, tested typhus, hepatitis, nephritis, and other chemical and biological weapons on concentration camp inmates.

[9] Gutzeit was in charge of hepatitis research for the German Army, and he and his colleagues carried out virus experiments on mental patients, Jews, Russian POWs and Gypsies in Sachsenhausen, Auschwitz and other locations.

[11] In 1943, Blome proposed spreading malaria "artificially by means of mosquitoes" and experimented on prisoners at Dachau and Buchenwald with lice in order to cause typhus epidemics.

[12] Eduard May, director of the Entomological Division of the SS Institute for Practical Research in Military Science, received a commission to experiment on concentration camp prisoners with "humanly harmful insects" starting in October 1943, which was closely connected with Blome's biological warfare program.

[15] Blome also worked on aerosol dispersants and methods of spraying nerve agents like Tabun and Sarin from aircraft, and tested the effects of these gases on prisoners at Auschwitz.

[16] This led Blome to experiment with the dispersal of insecticides, fungicides and nerve gas from aircraft, especially after Hitler had ordered a "drastic increase" in the production of Tabun and Sarin at I.G.

He informed Walter Schreiber, head of the Wehrmacht's Military Medical Inspectorate, that he was "very concerned that the installations for human experiments that were in the institute and recognizable as such, would be very easily identified by the Russians.

Blome brought his biological cultures with him from Poland, and was still promising Hitler a Wunderwaffe or 'miracle weapon' that would turn the tide of war in Germany's favor, but the Geraburg facility was captured by the U.S. Army in April 1945, along with its records and equipment.

Hojo Enryo, a Japanese Army doctor and expert in biological weapons "frequently visited the Robert Koch Institute as well as companies under German occupation to collect information about research on bacteriological warfare" and gave a lecture on this subject at the Berlin Military Academy of Medicine in October 1941.

After his arrival at the castle a secret message was transmitted to Operation Alsos, an Anglo-American team of experts, tasked with investigating the state of German and Italian weapons technology towards the end of the war:In 1943 Blome was studying bacteriological warfare, although officially he was involved in cancer research, which was however only a camouflage.