His uncle, Emil von Zelewski, died in 1891 as commanding officer of the Schutztruppe of German East Africa while fighting the Hehe.

In 1924, he resigned his army commission (or was discharged) and returned to his farm in Düringshof (now Bogdaniec in the Gorzów Wielkopolski county of Poland).

[10] During this period he reportedly quarreled with his staff officer, Anton von Hohberg und Buchwald,[3] and had him killed during the Night of the Long Knives in 1934 (for which he was convicted of manslaughter in 1961).

[7] A Nazi Party member of the Reichstag from 1932–44, Bach-Zelewski participated in the Night of the Long Knives in 1934, using the opportunity to have his rival Buchwald murdered.

[citation needed] In November 1939, SS chief Heinrich Himmler offered Bach-Zelewski the post of "Commissioner for the Strengthening of Germandom" in East-Silesia (the Polish territories incorporated into Silesia in 1939).

[12] Bach-Zelewski provided the initial impetus for the building of Auschwitz concentration camp[13] at the former Austrian and later Polish military barracks in the Zasole suburb of Oświęcim due to overcrowding of prisons.

From July to September 1941, he oversaw the murder of Jews in Riga and Minsk by the Einsatzgruppe B, led by Arthur Nebe, also visiting other sites of mass killings such as Bialystok, Grodno, Baranovichi, Mogilev, and Pinsk.

Bach-Zelewski regularly cabled to headquarters on the extermination progress; for example, the 22 August message stated: "Thus the figure in my area now exceeds the thirty thousand mark".

[16] In February 1942, he was hospitalized in Berlin for treatment of "intestinal ailments" stemming from opium abuse, and was described as suffering from "hallucinations connected with the shooting of Jews".

He was the only HSSPF in the occupied Soviet territories to retain genuine authority over the police after Hans-Adolf Prützmann and Friedrich Jeckeln lost theirs to the civil administration.

[citation needed] Bach-Zelewski's methods produced a high civilian death toll and relatively minor military gains.

In fighting irregular battles with the partisans, his units slaughtered civilians in order to inflate the figures of "enemy losses"; indeed, far more fatalities were usually reported than weapons captured.

Even when successful in pacification actions, Bach-Zelewski usually accomplished little more than to force the real enemy to relocate and multiply their numbers with civilians enraged by the massacres.

[25] In July 1943, Bach-Zelewski received command of all anti-partisan actions in Belgium, Belarus, France, the General Government, the Netherlands, Norway, Ukraine, Yugoslavia, and parts of the Bezirk Bialystok.

[citation needed] In early 1944, he took part in front-line fighting in the Kovel area, but in March he had to return to Germany for medical treatment.

[citation needed] On 2 August 1944, Bach-Zelewski took command of all German troops fighting Bor-Komorowski's Home Army that had staged the Warsaw Uprising.

The German forces were made up of 17,000 men arranged in two battle groups: under Hanns von Rohr [de], and under Heinz Reinefarth – the latter included the Dirlewanger Brigade of convicted criminals.

Units under his command murdered approximately 200,000 civilians (more than 65,000 in mass executions) and an unknown number of prisoners of war, in numerous atrocities throughout the city.

[26] After more than two months of heavy fighting and the almost total destruction of Warsaw, Bach-Zelewski managed to take control of the city, committing atrocities in the process, notably the Wola massacre.

[29] Incidentally, during the slaughter and razing of Warsaw, he is alleged to have personally saved Fryderyk Chopin's heart, by taking it for his own collection of curiosities.

[30] In October 1944, he was sent by Hitler to the Hungarian capital Budapest, where he participated in the fall of Regent Miklós Horthy and his government, and its replacement by the fascist and highly anti-Semitic Arrow Cross Party with their leader Ferenc Szálasi.

"[32] In saying so, Bach-Zelewski effectively linked the facts of mass murder on the ground to Nazi ideology, and established the connection between the Wehrmacht and the actions of the Einsatzgruppen in the Soviet Union, which turned out to be of great value to interrogators and prosecutors at the Nuremberg Trials.

Most modern historians dismiss Bach-Zelewski's claim and agree that a U.S. Army contact within the Palace of Justice's prison at Nuremberg most likely aided Göring in his suicide.

[34] In 1951, Bach-Zelewski was sentenced to 10 years in a labor camp for the murder of political opponents in the early 1930s; however, he did not serve prison time until February 1961, when he was convicted of the manslaughter of Anton von Hohberg und Buchwald, an SS officer, during the Night of the Long Knives.

[18] He had at the same time "denounced Himmler's racism in strong terms, as well as incitement to ‘exterminate "inferior races", possibly to curry favor with prosecutors.

[33] Bach-Zelewski died in Harlaching Hospital after transfer from Stadelheim Prison due to illness in Munich on 8 March 1972, a week after his 73rd birthday.