In September 1938 the SS-owned company Deutsche Erd- und Steinwerke (DEST) (English: German Earth & Stone Works) bought the defunct brickyard (German: Klinkerwerk) in Neuengamme. On 13 December 1938 the Neuengamme concentration camp was set up, with the first 100 prisoners coming from the Sachsenhausen concentration camp.
In April 1940 the SS and the city of Hamburg signed a contract for the construction of a larger brick factory, and on 4 June the Neuengamme concentration camp became an independent main camp.
According to the testimony of Wilhelm Bahr, an ex-medical orderly, during the trial against Bruno Tesch, 200 Russian prisoners of war were gassed by prussic acid in 1942. In April 1942, a crematorium was constructed at the camp. Prior to that all bodies were taken to Hamburg for cremation. In late 1943, most likely November, Neuengamme recorded its first female prisoners according to camp records. In the summer of 1944, Neuengamme received many women prisoners from Auschwitz, as well as other camps in the East . All of the women were eventually shipped out to one of its twenty-five female subcamps.
In July 1944, a camp section for prominent prisoners from France was set up. These were political opponents and members of the French resistance who had taken up arms against German forces. They included John William, who had participated in the sabotaging and bombing of a military factory in Montluçon. William discovered his singing voice while cheering his fellow prisoners at Neuengamme and went on to a prominent career as a singer of popular and gospel music. At the end of 1944 the total number of prisoners was around 49,000, with 12,000 in Neuengamme and 37,000 in the subcamps.
On 15 March 1945 the transfer of Scandinavian prisoners from other camps to Neuengamme started. This was part of the White Buses program. On 27 March a Scandinavian camp was established at Neuengamme. On 8 April an air raid on a train transporting prisoners led to the Celle massacre.
Aerial shot of the Neuengamme camp taken by British aviation on 16 April 1945
On 26 April 1945 about 10,000 surviving prisoners were loaded into four ships: the passenger liners Deutschland and Cap Arcona and two large steamers, SS Thielbek and Athen. The prisoners were in the ships' holds for several days without food or water.
The order to transfer the prisoners from the camps to the prison ships came from the Hamburg Gauleiter Karl Kaufmann who was himself acting on orders from Berlin. Kaufmann later claimed during a war crimes tribunal that the prisoners were destined for Sweden. However, at the same trial, the head of the Hamburg Gestapo, Georg-Henning Graf von Bassewitz-Behr, said that the prisoners were in fact slated to be killed in compliance with Himmler's orders, and it has been suggested that the plan called for scuttling the ships with the prisoners still aboard.
On 2 May 1945 the SS and the last prisoners left the Neuengamme camp.
On 3 May 1945 the ships were attacked by three squadrons of Royal Air Force Hawker Typhoons. The RAF believed the ships carried SS personnel who were being transferred to Norway; intelligence that the ships carried concentration camp prisoners did not reach the squadrons in time to halt the attack. The Thielbek was sunk and the Cap Arcona and Deutschland set on fire, they both later sank; survivors who jumped into the water were strafed by cannon fire from the RAF aircraft. Thousands of dead were washed ashore just as the British Army occupied the area; the British forced German prisoners-of-war and civilians to dig mass graves to dispose of the bodies. Approximately 7,000 prisoners were killed, with only 450 surviving.