In about a day, fans of the South Korean music group BTS, known as Army, have matched the group’s donation of $1 million to various charities supporting racial justice. 

On Saturday night, BTS revealed their donation to Variety, which appears to be one of the largest celebrity checks written thus far to the U.S. Black Lives Matter movement. On Sunday night, Army (which stylizes its name in all caps) followed up by pitching in more than $1 million. At the time of this article’s publication, the total reads $1.2 million—and it’s still rising.

Using hashtags #MatchAMillion and #MatchTheMillion, the fan-led fundraiser was spontaneously organized through social media after Army learned of BTS’s donation, with no direction from the music group itself. One in an Army, a charity program within the community with a history of running fundraising campaigns, served as central command.

“We’ve run big projects before, but the amount of support for this project is overwhelming,” a program spokesperson stated in a press release. “We’re so proud that Army have once again channeled their power for good and are making a real impact in the fight against anti-black racism.”

Their success may come as a surprise to some, but to those familiar with BTS’s fan organizations, it’s anything but—the groups were able to move quickly because the structures and practices for this scale of collective action have long been in place. Army has been known to rally to trend hashtags to promote new work from the group and stream music videos in concentrated sessions to rack up views. A foundation of dedicated Twitter accounts announce hashtags, monitor and report statistics, and disseminate information. 

A 24-hour deadline carries unusual distinction among BTS fans as a benchmark for achievement. It has proved effective: The group’s hit single “Boy With Luv” holds the world record for the most viewed YouTube video in 24 hours, the fandom holds the record for the most tweets under a single hashtag in 24 hours, and the group itself holds the record for most No. 1 chart spots held by a Korean album in 24 hours.

So the BTS fandom is used to mobilizing with hairpin agility. Consider the following example from last night: Less than an hour away from reaching $1 million, fans were discussing the hashtag they should use to celebrate their success. At first, they circulated #ArmyMatchedAMillion. But then a few fans suggested #2MforBLM “to make it not about us and show priority for the cause,” as one wrote. Within minutes (and thanks to myriad retweets) most of the community knew of the change of plans—and minutes later, when the $1 million goal was hit, #2MforBLM began trending worldwide.

A charitable ethos has been in place, too. A week before BTS’s donation was revealed, One in an Army had set up a channel for fans to split donations between organizations for racial justice—the group’s donation only galvanized its use. Over the past few years, fans have donated toward causes around the world, addressing such problems as environmental degradation, homelessness, and pediatric cancer; they have also adopted a zoo of animals such as whales, koalas, and Hoseok the deer, a creature in Germany christened after group member J-Hope.

The #MatchAMillion campaign now has a permanent page on One in an Army’s website. “Black Lives Matter isn’t something that has a time limit,” said the One in an Army spokesperson. A powerful grass-roots organization doesn’t, either.