HBO responded to an organized Twitter protest Sunday night against the network’s planned alternate-history slavery drama from Game of Thrones creators David Benioff and D.B. Weiss and writer-producers Nichelle Tramble Spellman and Malcolm Spellman.

The #NoConfederate rallying cry of those opposing HBO’s announced present-day slavery series Confederate trended through the night Sunday on Twitter.

Activist April Reign, the creator of the #OscarsSoWhite, made a call Friday for the Twittersphere to tweet using the new hashtag to “send a message” to the premium cable network during Sunday’s episode of Game of Thrones.

Game of Thrones creators David Benioff and D.B. Weiss are behind the planned HBO series set in an alternate reality in which the South seceded from the Union and slavery still exists.

After last week’s announcement, critics objected on many fronts, including the show’s intention to depict slavery as a legal institution and that two white men, Benioff and Weiss, would be running the series.

HBO program chief Casey Bloys acknowledged the network erred in how it released news of the series.

“HBO’s mistake was that we would be able to announce an idea that is so sensitive and requires such care and thought on the part of producers in a press release. (That) was misguided,” Bloys told writers at the summer TV press tour Wednesday.

Prior to the start of Game of Thrones, Reign shared a screenshot, stating that #NoConfederate was second in line for most trending topics in the United States.

She tweeted throughout the show, supporting one Twitter user’s suggestion that HBO instead pick up Underground, a canceled WGN America’s series about the Underground Railroad starring Jurnee Smollett-Bell and executive produced by John Legend. She also retweeted users 140-character or less protests, like one who reasoned, “Because we are your customers too #NoConfederate.”

HBO released a statement Sunday to The Hollywood Reporter in response to the swelling backlash.

“We have great respect for the dialogue and concern being expressed around Confederate,” the network said in the statement. “We have faith that…