The Wehrmacht was the German Army in the Third Reich. The Wehrmacht collaborated with the Nazis throughout their time in power to help them achieve their ideological aims, such as Lebensraum and the extermination of Jews and others.
Generally, prior to the Second World War, soldiers and armies adhered to the Hague Conventions of 1899 and 1907 (and Geneva Protocol of 1925), which laid out the accepted international laws of war and war crimes. Under these conventions, civilians and civilian property were protected and there were regulations on the welfare of prisoners of war and chemical and biological warfare were banned.
In the Second World War, many of the Wehrmacht soldiers did not adhere to the Hague Convention and instead actively helped the Nazis to persecute and murder the Jews of Europe, as well as other racial victims such as eastern European civilians and Roma. Orders from the Nazi high command, such as the Guidelines for the Behaviour of the Troops in Russia (issued on 4 June 1941), which advocated ruthless action against communists, partisans, saboteurs and Jews and the total elimination of all who resisted the Nazi rule in any way, guided the Wehrmacht and their actions.
During the invasion of the Soviet Union, the Wehrmacht provided vital logistical support, in the form of supplies, organisation, transport, to the Einsatzgruppen. This support allowed the Einsatzgruppen to successfully and quickly carry out their orders across the Soviet Union. In some instances, the Wehrmacht also took part in or independently carried out mass killings, such as at the Babi Yar massacre.
The Wehrmacht were also complicit in the death of millions of Soviet Prisoners of War (POWs). As Soviets were thought of as racially inferior by the Nazis, the Wehrmacht intentionally did not provide them with shelter or medical care, and only allowed them inadequate amounts of food. Approximately 3.3 million Soviet Prisoners of War died under the care of the Wehrmacht.
Although some Wehrmacht soldiers resisted and refused to carry out murders of civilians or prisoners of war, they were a minority overall.