Fox News is reportedly declining to run an ad for a documentary warning against the potential of fascism taking root in the United States, featuring footage from an actual Nazi rally at Madison Square Garden. The network deemed the spot "not appropriate for our air."

The 30-second ad-buy was intended to promote Marshall Curry's Oscar-nominated documentary short A Night At The Garden, which was made from archival footage of a 1939 rally that brought 20,000 American Nazi-supporters into the heart of Manhattan. The film's distributor tried to purchase a national spot on Sean Hannity's primetime show this week, but was rebuffed by the network's CEO Suzanne Scott, according to the Hollywood Reporter.

"It’s pretty breathtaking that the CEO of Fox News would step in to make sure Hannity viewers didn’t see this historical footage," Curry told Gothamist on Thursday. "It is a chapter of our country’s history that has to be confronted and not hidden from. The old line about people who don’t know their history being doomed to repeat it—it’s true."

The ad was initially scheduled to air locally—regional ad buys aren't controlled by the network—but was preempted by coverage of President Trump's rally in El Paso, Texas on Monday. That rally, in which the president railed against the "fake news" media and repeated lies about the city's violent crime rate to a roaring crowd, was briefly interrupted by a Trump supporter attacking a BBC photographer.

Curry's film, meanwhile, centers on the largely forgotten "Pro American Rally" at the former MSG site on Eighth Avenue and West 50th Street. Archival footage of the 1939 event, unearthed by Curry and the documentary project Field of Vision, shows thousands of well-dressed Americans giving the Nazi salute to an American flag, a portrait of George Washington, and a Swastika. Fritz Kuhn, leader of the influential German-American Nazis group known as the Bund, can be heard speaking of a "white, gentile-ruled United States... free from Jewish Moscow-directed domination."

When we spoke with Curry in 2017, he told us that the film "illustrated that the tactics of demagogues have been the same throughout the age. They attack the press, using sarcasm and humor. They tell their followers that they are the true Americans (or Germans or Spartans or…). And they encourage their followers to take their country back' from whatever minority group has ruined it."

The rally is also considered a defining moment for the emerging anti-fascist movement in the United States. Nazi supporters were greeted by an estimated 100,000 furious New Yorkers, including one 26-year-old plumber's helper who stormed the stage and was swiftly beaten up by Nazis and arrested by the NYPD. Following the violence in Charlottesville, historian and author Arnie Bernstein spoke to Gothamist about the parallels between the two historical moments, and the ways in which the Bund were ultimately stopped.

"The difference, though, is that Roosevelt didn’t react to this with winks and nods and coded language," Bernstein added. "We saw the campaign that Trump ran. We saw a president that did not mention Jews on Holocaust Remembrance Day. He was basically forced into making that speech [condemning violence in Charlottesville.] He’s been winking and nodding to this all along."

Neither Fox News, nor Sean Hannity—who previously appeared on stage at a Trump rally last year—responded to Gothamist’s request for comment.

You can watch the full ad that was rejected by Fox below:

A Night at The Garden: "It Can Happen Here" (Broadcast Spot) from Field of Vision on Vimeo.

UPDATE 3:00 p.m. In a statement to Gothamist, Fox News Ad Sales President Marianne Gambelli said, “The ad in question is full of disgraceful Nazi imagery regardless of the film’s message and did not meet our guidelines."

Asked why the network had run a previous trailer featuring Nazi imagery for conservative activist Dinesh Dsouza's film Death of a Nation, a spokesperson said she could not elaborate beyond the statement.