'Aktion 1005' was a German undertaking as part of the effort to conceal or obliterate evidence that people had been murdered by the Germans in 'Reinhard' within occupied Poland (May 1942/1944)

Otherwise known as 'Sonderaktion 1005' (Special Action 1005) and 'Enterdungsaktion' (Exhumation Action), this was undertaken in the strictest secrecy, beginning in May 1942 and lasting into 1944. The operation exploited prisoners for the exhumation of mass graves and the incineration of the bodies. One year after the start of 'Aktion 1005', the operation was enlarged into the occupied territories within Eastern Europe in an effort to destroy evidence of the 'Final Solution'. The task of 'Aktion 1005' was to conceal the evidence of the massacres of several million persons by SS-Einsatzgruppen. 'Aktion 1005' was supervised by selected squads from the Sicherheitsdienst and Ordnungspolizei.

In March 1942, SS-Obergruppenführer Reinhard Heydrich placed SS-Standartenführer Paul Blobel in charge of the 'Aktion 1005', but the launch of the operation was delayed after Heydrich was assassinated in June 1942 in 'Anthropoid' and it was only after the end of June that SS-Gruppenführer Heinrich Müller, head of the Gestapo, finally gave Blobel his orders. While the primary objective was the erasure of all evidence of Jewish exterminations, 'Aktion 1005' was also to include non-Jewish victims of the SS-Einsatzgruppen.

Blobel began his work with experiments at Chełmno. Attempts to bring about the destruction of exhumed bodies by the use of incendiary bombs proved unsuccessful as the weapons set fire to nearby forests. The most effective way was eventually found to be huge fires on iron grills. The method involved the construction of alternating layers of corpses and firewood on railway tracks, and the remaining bone fragments were then crushed by pounding with heavy dowels or in a grinding machine, and then reburied in pits.

The operation officially began at Sobibór extermination camp. The Leichenkommando (corpse units) exhumed the bodies from mass graves around the camp and then burned them, after which task the workers were executed. The process then moved to Bełżec in November 1942. The Auschwitz and Belsen camps had on-site crematoria with furnace rooms for the disposal of bodies, so the 'Aktion 1005' teams were not needed there.

The semi-industrial incineration of corpses at the Treblinka extermination camp began as soon as the political danger associated with the earlier burials was realized. In 1943, the 22,000 Polish victims of the Katyn massacre by the Soviets were discovered near Smolensk in western Russia and reported to Adolf Hitler. The victims' remains were well preserved under the ground, attesting to the Soviet mass murder, and by April 1943 Nazi propaganda began to draw the attention of the international community to this war crime, and the Germans established the Katyn Commission to make detailed examinations in an effort to drive a wedge between the Allied powers. Meanwhile, secret orders for the exhumation of mass graves and the incineration the many thousands of victims instead came directly from the Nazi leadership in April. The corpses buried at Treblinka were dug up and cremated on the orders of Reichsführer-SS Heinrich Himmler, who visited the camp in March 1943. The instructions to make use of rails as grates came from SS-Scharführer Herbert Floss, the camp’s cremation expert. The bodies were placed on cremation pyres 100 ft (30 m)) long, with rails laid across the pits on concrete blocks. Petrol was splashed over the wood, and each pyre burned in a massive blaze attended by roughly 300 prisoners who operated the pyres. At Bełżec, the round-the-clock operation lasted till March 1943, and at Treblinka until the end of July.

The operation also revisited the locations of earlier massacres such as Babi Yar in Ukraine, Ponary in the Baltic states, the Ninth Fort in Lithuania and Bronna Góra in Belorussia.

By 1944, with Soviet armies advancing, SS-Obergruppenführer Wilhelm Koppe, head of the Reichsgau Wartheland ordered that each of the five districts of the Generalgouvernement’s territory set up its own 'Aktion 1005' commando to begin the so-called 'cleaning' of mass graves. The operations were not entirely successful, for the advancing Soviet forces reached some of the sites before they could be cleared.