A Texas history museum in Austin pulled out of an event featuring a new book about the Alamo just hours before it was scheduled to begin, the San Antonio Express-News reports.

The Bob Bullock Texas State History Museum was set to co-host an event featuring two of the authors of Forget the Alamo: The Rise and Fall of an American Myth on Thursday evening, but the writers said they were told the museum would be withdrawing because of concerns from its board of directors, which includes the two highest-ranking politicians in Texas: Gov. Greg Abbott and Lt. Gov. Dan Patrick. Both are conservative Republicans.

Forget the Alamo, by Bryan Burrough, Chris Tomlinson, and Jason Stanford, critically examines the myths that surround the famed San Antonio mission and argues that discussions about slavery are too often left out of the story about the battle. In a starred review, a critic for Kirkus called the book “an iconoclastic, romping, bull’s-eye volley at an enduring sacred cow—popular history at its most engaging and insightful.”

“I think we’re being censored, which is a shame because the mission of the Texas history museum is to promote examining our past,” co-author Tomlinson told the Express-News. “We’ve done more than a dozen events, and this is the first time we’ve been shut down like this.”

On Friday, literary nonprofit PEN America expressed concern about the museum’s decision to pull out of the event, writing in a statement, “If this was indeed an attempt to silence the speakers because they wrote a book that challenges the governor’s preferred historical narrative; it’s censorship, plain and simple.”

Michael Schaub is a Texas-based journalist and regular contributor to NPR.