[5] The program's operational guidelines were based on the policy of Lebensraum proposed by Adolf Hitler and the Nazi Party in fulfilment of the Drang nach Osten (drive to the East) ideology of German expansionism.

[16][17][18] Implementing it would have necessitated genocide[19] and ethnic cleansing on a vast scale to be undertaken in the Eastern European territories occupied by Germany during World War II.

[21] Hitler's doctrine of Lebensraum envisaged the mass-killings, enslavement and ethnic cleansing of Slavic inhabitants of Eastern Europe, followed by the colonization of these lands with Germanic settlers.

This was mentioned by SS-Obergruppenführer Erich von dem Bach-Zelewski during his evidence as a prosecution witness in the trial of officials of the SS Race and Settlement Main Office (RuSHA).

According to Bach-Zelewski, Himmler stated openly: "It is a question of existence, thus it will be a racial struggle of pitiless severity, in the course of which 20 to 30 million Slavs and Jews will perish through military actions and crises of food supply.

"[25] A fundamental change in the plan was introduced on June 24, 1941 – two days after the start of Operation Barbarossa – when the 'solution' to the Jewish question ceased to be part of that particular framework gaining a lethal, autonomous priority.

[27] A cost estimate of 45.7 billion Reichsmarks was included in the spring 1942 version of the plan, in which more than half the expenditure was to be allocated to land remediation, agricultural development, and transport infrastructure.

For example, by August–September 1939 (Operation Tannenberg followed by the A-B Aktion in 1940), Einsatzgruppen death squads and concentration camps had been employed to deal with the Polish elite, while the small number of Czech intelligentsia were allowed to emigrate overseas.

[21] "The treatment of the civilian population and the methods of anti-partisan warfare in operational areas presented the highest political and military leaders with a welcome opportunity to carry out their plans, namely, the systematic extermination of Slavism and Jewry."

In ten years' time, the plan effectively called for the extermination, expulsion, Germanization or enslavement of most or all East and West Slavs living behind the front lines of East-Central Europe.

The programme delineated various settler-colonial policies to be undertaken by Nazi Germany in Eastern Europe over a period of 25 years; such as the establishment of new settlements, demographic engineering, construction of new centres, etc., after the planned liquidation of the native populations.

While various Wehrmacht commanders wanted to portray Germans as "liberators" of Eastern Europe and incite anti-communist dissidents to foment a pro-Axis partisan warfare against Soviet Union, Nazi ruling elites sought outright suppression of what they regarded as Slavic "untermenschen".

"[50]German implementation of Nazi racial principles, combined with the severity of the war in the Eastern Front, resulted in German-occupation forces inflicting brutal measures during its anti-insurgency campaigns.

The Schutzstaffel military apparatus, packed with militants ideologically indoctrinated to view Slavs as subhumans, fanatically implemented "Herrenvolk vs. Untermensch" racist criteria in their dealings with natives.

[52] Even as deteriorating conditions in the front brought around a change in military strategy,[50] speeches of various Wehrmacht generals continued to explicitly and implicitly designate German fighters as "the last bulwark of European civilisation against Slav hordes".

[53] Exploiting anti-semitic sentiments which had persisted since the Tsarist period in occupied territories, collaborationism was also incited amongst the native inhabitants to assist Nazi Germany in implementing the Holocaust.

As a consequence of the ideological constraints of National Socialism and Wehrmacht's rising casualties across the Eastern Front, German units faced shortages of personnel in carrying out the "Final Solution".

[54] As anti-fascist partisan warfare intensified across the German-occupied territories of Eastern Europe, Poland, and Yugoslavia, Hitler stated on 6 August 1942: “We shall absorb or eject a ridiculous hundred million Slavs.

[55] According to Nazi intentions, attempts at Germanization were to be undertaken only in the case of those foreign nationals in Central and Eastern Europe who could be considered a desirable element for the future Reich from the point of view of its racial theories.

Special institutes for children in occupied territories were operated to separate kids who were categorised by Nazi authorities as "racially suitable" from the local inhabitants, wherein they were indoctrinated to be transferred to families in Germany.

[58] Despite the obstruction of German war efforts by the colonization policies and scorched earth tactics unleashed against native populations, Himmler dogmatically pursued the implementation of GPO programme and proposed the further expansion of Konrad Meyer's plan.

[59] GPO policies hindered the German military from efficiently exploiting the resources from occupied territories during 1942, a decisive phase of the war during which Axis forces had the capability to potentially win in the Eastern Front, before the Red Army could amass more strength.

[60] After the German defeat at the Battle of Stalingrad and other Axis setbacks in the Eastern Front, Nazi planners were forced to practically abandon the extermination campaigns of the GPO by mid-1943.

[61][62] From spring 1943, SS adopted the "Vernichtung durch Arbeit" (trans: "Extermination through labour") policy, which focused on exploiting natives in occupied territories as forced labor to aid German economy and military industry.

[64][8] Nazi Germany conducted its warfare in the Eastern Front as a colonialist campaign of plunder and slaughter, involving the unhinged looting of resources and wholesale terrorism against native populations.

Such concessions were non-existent in Poland, Ukraine and Belarussia, where the Germanic occupation policy was characterised by full-blown colonization, exploitation of resources, state-terrorism and forcing natives into slave labour.

[58] Nazi anti-insurgency warfare conducted across occupied Eastern Europe was also used as an opportunity by German authorities to advance the objectives of GPO and Lebensraum settler-colonial agenda.

[70]: 32  A majority of them, now deprived of their leaders and most of their intelligentsia (through mass murder, destruction of culture, banning education above the absolutely basic level, and kidnapping of children for Germanization), would have to be deported to regions in the East and scattered over as wide an area of Western Siberia as possible.

[97] A major document which enabled historians to accurately reconstruct the Generalplan Ost was a memorandum released on April 27, 1943, by Erhard Wetzel [de], director of the NSDAP Office of Racial Policy, entitled "Opinion and thoughts on the master plan for the East of the Reichsführer SS".

[105] According to historian Norman Naimark: "If the awful counterfactual of a Nazi victory had come to pass, not just Soviet soldiers, but Russians, Belarusians and Ukrainians would surely have shared the fate of the Poles and been eliminated culturally and ethnically as distinct peoples and nations.