It happened again. The suspect in the El Paso shooting is the latest in a ghoulish parade of white men who in recent years have taken it upon themselves to gun down crowds of civilians in the name of defending their race from the nefarious plots of suspected "invaders" bent on destroying white civilisation from within.

The document written by the shooter credits the "Great Replacement" as his central motivation. Also known as "white genocide", this is the increasingly popular conspiracy theory that the white race and the entirety of "western civilisation" are besieged by the combined forces of non-white migration and dwindling white birth-rates, orchestrated by multicultural, globalist [read: Jewish] elites in an attempt to undermine the integrity of white life. For the shooter, this could not be allowed to stand.

He killed 22 people, and injured many more. Add that to the toll of 77 murdered by Anders Breivik, and the black churchgoers murdered by Dylan Roof, both of whom saw themselves as the first soldiers in an all-out "race war" for the survival of white people. Add those to the 11 murdered at the Tree of Life Synagogue, by someone set out to punish Jewish people for orchestrating an "invasion" of migrants. At the Unite the Right Charlottesville rally, neo-Nazis chanted "Jews will not replace us" – and then, one of them killed a counterprotester. The Christchurch shooter, who killed 52 people, titled the document he left behind "the Great Replacement". “It’s the birthrates.” he insisted. “It’s the birthrates. It’s the birthrates.” This is paranoiac race-war fanaticism newith an ever-growing body count.

The phrase "the great replacement" was coined by white supremacist French philosopher Renaud Camus, in his alarmist 2012 screed of the same name. He wrote that French society is critically endangered by an onslaught of non-white, Muslim migration, a pattern of "reverse colonisation" reflected across the western world which has left white cultures – and national securities – under siege from hostile forces. He denies seeing the white race as "superior", insisting rather that he’s neutrally concerned about the integrity and survival of an ethnic group facing down an exterior threat; an undeniable concern, surely. But the victims and their aggressors are clear; Camus uses hysterically inflated statistics and good old-fashioned reactionary nativism to describe white Europeans being “invaded” and “occupied” by a vicious army of black and brown people, with catastrophic results. Providing academic structure to a concocted sense of white victimhood has earned Camus a vaunted place as the darling of the global alt-right. He’s a doyen of the New Right in France, whose youth movement Génération Identitaire spawned a network of international versions in Generation Identity and Identity Evropa. These anti-migrant, anti-Muslim groups have found champions in Richard Spencer, Lauren Southern and Katie Hopkins - and in the Christchurch shooter.

The shadow of the Great Replacement conspiracy looms large over the mainstream right. Tucker Carlson has accused US Democrats of orchestrating “demographic replacement,” with a “flood of illegals” to create “a flood of voters for them”. In 2013, Nigel Farage intimated that some Muslim people are “coming here to take us over”.

Steve Bannon, Trump’s former chief Strategist notoriously cited The Turner Diaries, a novel considered the “bible of the racist right”, in which white men heroically take up the struggle for the survival of the white race, suffering under near-future tyranny of black people, migrants and jews. For his part, Trump’s has anointed himself a similar hero, the champion of the beleaguered working whites, helping them throw off the yoke of globalisation.

Public-facing theories about the Great Replacement, playing for popular respectability, usually eschew direct reference to white supremacy, favouring the altogether more slippery language of diversity, cultural preservation and of self-defence. Hence, the insistence among the "identitarian" right, that if BAME people can talk about defending the survival of their own cultures and races, then so can white people. The El Paso manifesto decried “shameless race mixers” for “destroy[ing] genetic diversity”.

These excuses are just as flimsy as they sound, collapsing into all-out racism under the weight of the slightest scrutiny. The soft-shuffle manoeuvre from race to culture is a routine canard of the far right to avoid accountability, and handwringing about "cultural preservation" is nothing but a dog whistle for those embarrassed to openly show their disgust for miscegenation. Moreover, the steady effects of demographic change and cultural mixing are only worrisome if you’re clinging to a rabid ideal of ethnocultural purity; a foundational doctrine of fascists everywhere. There is precisely zero evidence that "liberal elites" would be interested in the fatal dilution of whiteness, even if they did indeed have shadowy cabals of Jewish people to put their plans in motion. None of this really matters; the conspiracy is less about levelling a statistically robust world picture, and more about telegraphing a sense of global white victimhood around which to arrange a sense of political outrage. It’s about mobilising an age-old panic to build a case for extreme racial violence.

This is bait-and-switch white supremacy for media-savvy crypto-fascists distantly aware that calling for the all-out extermination of black and ethnic minority people doesn’t play well on the TV (at least for now). Better instead to gloss it with a thin patina of plausible deniability; talking diversity rather than supremacy, preservation rather than extermination.

But really, fears of a white population overwhelmed by racial others is nothing new.

The spectral menace of the "race war" has long haunted our political imaginaries; a frenzied Caucasian cautionary tale in which BAME people and migrants, when inadequately punished and cowed, wreak extraordinary vengeance on the white man. It can be found in desperate petitions to preserve chattel slavery as a backstop against the supposed threat of violent black people. Thomas Jefferson described the institution of slavery as “holding a wolf by the ears”. In 1898, Winston Churchill cautioned against the “militant Mahommedanism” of migrant workers. In 1968, Enoch Powell declared that an influx of migrants meant "the black man [would] have the whip hand over the white man".

If you buy into this world picture (and many, many do), any step towards racial inequality becomes an unthinkable concession to a deadly set of enemies who must be crushed – or else. If you buy into this world picture, must be prepared to do whatever it takes to survive.

This, of course, is precisely the point.

Of all the swivel-eyed conspiracies shambling through the more squalid reaches of the internet, the Great Replacement has proved uniquely powerful. Its doctrine of survival is a captivating persuasion tactic for people bent on drawing more people to the cause of white supremacy. It crams children into cages in detention centres, and it puts guns in the hands of men wishing to exorcise their bloody power fantasies. And it veils the real operation of violence, recasting terrorism as heroism and tyranny as the tactical necessities of self-defence.

The El Paso shooter allegedly wrote: “I can no longer bear the shame of inaction knowing that our founding fathers have endowed me with the rights needed to save our country from the brink of destruction.” Such is the mythos of the Great Replacement. It reaches out a hand to the foetid, trembling, paranoid soul of white supremacist culture and tells it that everything it has ever feared is coming true. But that we have the power to stop it. It asks – do you want to be a hero, kid? I can tell you how to be a hero. Just follow me.