The white nationalist rally that took a deadly turn in Charlottesville, Virginia, during the summer of 2017 shocked Americans with its front-row view of hatred on the rise. But weeks before the violence, organizers were making preparations for the gathering in a corner of the internet.

Using a private server on a platform designed for online gaming, supporters of the rally discussed everything from restroom access to what to wear and what weapons they could legally bring (guns, knives, pepper spray) to the August rally.

Those online chats are now at the heart of a lawsuit that accuses more than two dozen individuals and entities, including white supremacists, of engaging in a violent conspiracy to violate the rights of the counterdemonstrators who gathered in Charlottesville to denounce racism and anti-Semitism.

During the weekend’s events, a neo-Nazi plowed his car into a crowd of counterdemonstrators, killing a woman and injuring dozens of other people.

The 11 plaintiffs in the lawsuit are using the online conversations to bolster their claim of a conspiracy.

“In many ways, social media has become the Klan den of the 21st century,” said Amy Spitalnick, executive director of Integrity First for America, the nonprofit organization funding the civil case.

In fact, the lawsuit invokes a post-Civil War federal law written to protect black Americans from oppression by the Ku Klux Klan.

The case, which the plaintiffs anticipate will go to trial sometime next year, is a bid to connect online speech by far-right groups to real-world violence.

It comes amid a string of deadly extremist attacks around the world in which the alleged killers used the internet to share their views or signal their intentions. Those attacks include the Pittsburgh synagogue massacre last year that left 11 people dead and the slaughter of 51 people at two New Zealand mosques in March.

The Charlottesville plaintiffs, most of whom took part in the counterdemonstrations, are seeking unspecified compensatory and punitive damages as well as an injunction limiting the defendants’ behavior.