The programme targeted former officials and members of mainstream centre and left-wing "Bourgeois" parties from the period of democratic government that were declared illegal after January 1933.
"Gewitter" is a German word for a "thunder storm" and Heinrich Himmler was a senior member of the government whose areas of responsibility included policing and a wide range of other matters administered in his capacity as Minister of the Interior.
The mass arrests of Aktion Gitter were neither unprecedented nor a spontaneous government response to the assassination attempt of July 1944, but the working through of long-standing policies.
On 14 August 1944 SS Chief Heinrich Himmler received the mandate to have former Social Democratic (SPD) and Communist Party (KPD) officials detained.
The mass arrest, which was estimated to cover more than 5,000 former politicians, should take no account of whether or not those detained were still engaged in opposition activity, and was not connected with the search underway for the July assassination plotters.
On 21 August the order was extended so that pre-1933 assembly members from the old Centre Party were also to be detained, although this broadening of the scope of The Aktion was partially rescinded two days later.
Some of the concentration camps receiving the largest numbers of "Aktion Gitter" detainees were at Neuengamme near Hamburg (650), Buchenwald near Weimar (742)[5] and Dachau near Munich (860).
It gave notice that under Hitler the war would be fought by Germany to the bitter end - in his own words "till five minutes past midnight" - regardless of how hopeless the cause had become...[8]
The way in which the mass arrests were carried out triggered such popular resentment that one week later on 30 August 1944, Ernst Kaltenbrunner ordered a review that led to some mitigation.
Former national Reichstag Gitter detainees who did not survive the concentration camps included Otto Gerig [de], Karl Mache and Heinrich Jasper.
Former member of the Reichstag Friedrich Puchta [de] initially survived his death march out of Dachau and lived to see liberation, after which he was immediately hospitalised.
Other Gitter detainees perished when the SS Cap Arcona, by then used as a prison ship and moored off Lübeck, was sunk by the British Royal Air Force the day before the German military surrender.