On a freezing night in November, as police sprayed nonviolent Dakota Access Pipeline opponents with water hoses and rubber bullets, representatives of the FBI, the Bureau of Indian Affairs, North Dakota's U.S. Attorney's Office, and local law enforcement agencies frantically exchanged emails as they monitored the action in real time.

"Everyone watch a different live feed," Bismarck police officer Lynn Wanner wrote less than 90 minutes after the protest began on the North Dakota Highway 1806 Backwater Bridge. By 4 a.m. on November 21, approximately 300 water protectors had been injured, some severely. Among them was 21-year-old Sophia Wilansky, who nearly lost her arm after being hit by what multiple sworn witnesses say was a police munition.

The emails exchanged that night highlight law enforcement efforts to control the narrative around the violent incident by spreading propaganda refuting Wilansky's story, demonstrate the agencies' heavy reliance on protesters' social media feeds to monitor activities, and reveal for the first time the involvement of an FBI informant in defining the story police would promote.