Holocaust: The Holocaust wasn't just about Jews. A generation of gypsies and gays was also consumed in the Nazi death camps, writes Daniel McLaughlin.
The world knows it as the Holocaust but for the Gypsies, who lost perhaps half a million people to the Nazi death camps, it is called Porrajmos: the Devouring.
Adolf Hitler drove Europe's Gypsy, or Roma, community along a parallel path to the Jews, subjecting them to violent discrimination in the 1930s, then squalid ghettos and SS killing squads, before sending them to the gas chambers at Auschwitz and elsewhere.
But as world leaders gather in southern Poland this week to mark 60 years since the liberation of Auschwitz, Nazi persecution of the Gypsies - as well as other "asocial and criminal elements", from homosexuals to Jehovah's Witnesses - is largely forgotten.
After coming to power in 1933, Hitler quickly passed laws to marginalise "non-Aryans" and people with hereditary health problems or an "habitually criminal nature".
Gypsies, whose appearance and way of life shared nothing with Nazi ideals, were an obvious target, and thousands of men and women were arrested and forcibly sterilised on orders from Heinrich Himmler's Office for the Fight Against the Gypsy Nuisance.
In 1939 their fate passed into the hands of Adolf Eichmann, a chief co-ordinator of the Holocaust, who shoved thousands of Roma into prison camps and seething Jewish ghettos in occupied Poland.
By late 1942 - as marauding SS Einsatzgruppen units slaughtered countless Jews and Roma in Eastern Europe and the Soviet Union - Himmler had ordered 30,000 Gypsies into the cattle trucks that now rattled incessantly from the ghettos to the Polish death camps of Majdanek, Sobibor, Belzec and Treblinka.
More than 20,000 other Gypsies arrived at Auschwitz, where the "Angel of Death", Dr Josef Mengele, awaited them with particular enthusiasm.
As arrivals in Europe from northern India in the 1400s, the Gypsies had strong "Aryan" origins, and so were believed by Nazi doctors to be biologically far closer to Germans than were the Jews.
While Himmler considered sparing a few "pure-bred" Roma to serve as a kind of live ethnographic exhibit, Mengele thought Germans could benefit from experiments performed on other people with Aryan heritage - albeit irrevocably "sullied" by centuries of interracial breeding as the Roma moved north through Asia and the Balkans.
Mengele and colleagues killed thousands of Gypsies, many of them children, with tests for the navy on how long someone could survive on saltwater, for the Luftwaffe on the effects of altitude and pressure, and an array of other, more bizarre, procedures.
Records are incomplete, but about 20,000 Roma are believed to have died at Auschwitz alone, including 3,000 men, women and children on the night of August 2nd, 1944, when they were gassed to make way for trainloads of doomed Hungarian Jews.
August 2nd is the day when Gypsies remember the Devouring, a genocide that has been drowned by the sheer weight of Jewish remembrance of the Holocaust.
"Every Gypsy lost someone. No community in Europe, except Spain's, was untouched by this," says Mr Donald Kenrick, a Jewish expert on the subject. "At least 200,000 Roma died, but very often families didn't talk about it - through shame of being sterilised or forced to eat horsemeat - and many didn't read or write."
Mr Claude Cahn, of the European Roma Rights Centre in Budapest, says a growing willingness to discuss the Devouring - which was only recognised as genocide in 1982 by West German leader Helmut Schmidt - is helping Gypsies unite in their struggle against lingering prejudice.
"It is no wonder that the Holocaust is becoming a basis of Romany unification, in the recognition that Roma are one people with one common fate, and that the treatment suffered during the Holocaust is emblematic - if extreme - of the threat to Roma," he said.
But just as many Jews refuse to compare the Roma loss to their own, many Gypsies baulk at talk of the systematic Nazi persecution of homosexuals.
About 50,000 gays were sent to concentration camps in a vicious purge that followed the execution of Ernst Roehm, a leading Fascist and emerging rival to Hitler, on the so-called Night of the Long Knives in June 1934.
Afterwards, Roehm and allies in his radical Nazi "Brownshirt" militia were denounced as homosexuals, and a gay community that had flourished in the post-war Weimar Republic was persecuted along with Gypsies, alcoholics and criminals as antisocial elements.
Forced to wear a pink star and live in isolation from other inmates, gay prisoners performed menial and degrading work between regular beatings and floggings. Some were disingenuously promised freedom if they accepted castration or an experimental testosterone implant.
Himmler made his own pledge that any gay SS men would be shot: "Thereby, I hope finally to have done with persons of this type in the SS, and the increasingly healthy blood which we are cultivating for Germany will be kept pure."
A possible total of 10,000 homosexuals died in the Nazi pursuit of pure blood, forming a river that emptied, along with the Devouring, into the Holocaust's ocean of 11 million dead.
See Fintan O'Toole - Opinion
Tomorrow: Bringing the perpetrators to justice - how the Nazi hunters tracked down the guilty.