The vehicle attack that left a civil rights activist dead and 19 others injured on Saturday was the product of continuous incitement to violence across extreme rightwing echo chambers. After police announced the disbanding of the far-right protest in Charlottesville, Virginia, the live stream chat room of the “alt-right” writer Baked Alaska was flooded with calls to kill Jews, black people and counter-protesters. And members of the anti-communist channel in the chat application Discord vowed to push back harder “until the enemy is completely defeated”.

Shortly after the incident one user of the message board 4Chan wrote of the killer: “Whoever he is, he is a hero. I salute him.” Others expressed regret that the car had not been bigger, reflecting a climate of denial, justification and belittlement around the vehicle attack – mirrored in the White House’s muted response.

With thousands marching under the banner of “You will not replace us”, the event represented one of the largest gatherings of the US extreme right this century. Billed as a protest against the removal of the statue of the confederate general Robert E Lee, and in defence of freedom of speech, the rally attracted a broad church of groups from libertarians to white supremacists. Key figures from the alt-right, the far-right movement in the US, rubbed shoulders with militant constitutionalists, southern nationalists and neo-Nazis. Several branches of the Ku Klux Klan were in attendance, as well as delegations representing the white-supremacist Daily Stormer website and the notorious National Socialist Movement. The event was endorsed on the other side of the Atlantic by the Greek ultra-nationalists Golden Dawn and self-described German identitarians.

By hijacking topics such as the preservation of southern heritage, free speech, anti-left sentiments, and pro-white and anti-immigration attitudes, the organisers gained traction across this broad spectrum of extreme rightwing thinking. While the event was framed on /pol/ – 4chan’s “politically incorrect” message board – as a way to fight “a totalitarian communist crackdown” and “defend the right of southerners”, the Daily Stormer was rather more frank in promoting it as the starting point “to end Jewish influence in America”.

This illustrates a dangerous convergence of ideology and goals from groups that have traditionally been fragmented and prone to internal conflict. “Infighting is part of every movement – but it doesn’t have to be,” the radical libertarian politician Augustus Invictus, who was announced as a speaker at the rally, posted on Facebook. A few days before the Charlottesville rally, an article explaining Why We Should UniteTheRight was circulated on Gab, the alt-right’s Twitter equivalent. “We’re in the earliest stages of a mass movement” wrote the alt-right blogger Hunter Wallace. [Article continued on Guardian online].